Modulation of Pt electron transfer via engineered ultra-thin TiO_2-Al_2O_3 interfaces for coke-resistant methane dry reforming

Domain: chemistry
Published: 2026-03-09
Editorial outcome: major_revision

Abstract
Dry reforming of methane (DRM) is plagued by rapid catalyst deactivation, primarily due to carbon deposition exacerbated by exposed Al O surfaces in conventional mixed-phase supports. Herein, we construct a well-defined Pt/TiO -Al O interface by depositing an ultra-thin anatase TiO overlayer onto Al O via an in situ growth strategy to eliminate detrimental Al O exposure. Characterization coupled with DFT calculations reveal that the Al O support induces lattice contraction and electron enrichment of the ultra-thin TiO layer through interfacial stress and charge transfer. This concurrently activates lattice oxygen (Ti-O) and optimizes Pt charge density, endowing the catalyst with balanced CH activation and a heightened CH* → C* barrier. The resulting Pt/TiO -Al O catalyst achieves exceptional durability, maintaining 91% CH conversion at 800 °C for 100 h with negligible carbon deposition, outperforming Pt/Al O and Pt/TiO benchmarks. This work demonstrates that engineering a continuous ultra-thin TiO overlayer on Al O is a superior alternative to mixed-phase supports, providing a generalizable blueprint for coke-resistant catalyst design via precise interface control.

Introduction
Driven by escalating global energy demands and the urgent need to mitigate greenhouse gas emissions, the development of efficient energy conversion strategies has garnered significant attention. Among these, dry reforming of methane (DRM) emerges as a promising route. This reaction not only directly consumes two major greenhouse gases but also generates high-value-added syngas, which finds extensive applications in Fischer-Tropsch synthesis, hydrogen fuel production, and the synthesis of chemical products such as methanol and dimethyl ether1,2.

Compared with conventional methane reforming routes, DRM offers distinct environmental and process advantages. Steam reforming of methane (SRM, CH + H O → CO + 3H , ΔH = +206 kJ·mol-1) is a mature process that produces syngas at the industrial scale, but it requires a continuous supply of high-temperature steam and substantial external heat input. Partial oxidation of methane (POX, CH + 0.5O → CO + 2H , ΔH = –36 kJ·mol⁻¹) can be thermally self-sustained. However, the intense local heat release can create hot spots leading to safety concerns, and it may still suffer from carbon deposition3. In contrast, DRM (CH + CO → 2CO + 2H , ΔH = +247 kJ·mol⁻¹) directly utilizes CO together with CH to generate syngas without addition of steam or oxygen. Its high-temperature operation also enables effective integration with renewable heat or industrial waste-heat sources. As a result, DRM offers higher carbon utilization efficiency and potential process-level energy benefits, making it an attractive route for sustainable energy conversion4.

Despite the significant chemical and environmental importance of DRM, its industrial implementation remains hindered by severe catalyst deactivation, primarily due to carbon deposition and metal sintering under high-temperature conditions (700–900 °C)5,6. Carbon accumulation not only passivates active sites but also obstructs reactant diffusion, disrupts metal-support interfaces, and undermines catalyst porosity and mechanical integrity7,8.

Ni-based catalysts are widely studied due to their high CH activation ability and low cost. To improve their long-term stability in DRM, strategies such as introducing promoters, alloying Ni with other metals, and constructing confinement structures have been explored9–12. However, the inherent tendency of Ni to promote carbon formation and to undergo sintering under DRM conditions remains a major limitation for achieving long-term durability. In contrast, noble metals such as Pt generally exhibit a much higher intrinsic resistance to carbon deposition, which allows for a clearer investigation of coke suppression and interfacial reaction mechanisms under harsh reforming conditions1.

Building on these insights, many efforts have focused on enhancing CO adsorption and activation for oxidative carbon removal. These include: (i) introducing oxygen vacancies in reducible oxide supports, which capture CO and generate reactive oxygen species capable of oxidizing deposited carbon13–15; (ii) increasing the surface basicity of supports to promote CO chemisorption and facilitate the formation of stable carbonate intermediates, thereby suppressing carbon nucleation and growth16–18; (iii) leveraging metal-support interfacial synergy, where active interfacial sites promote CO dissociation into oxygen-containing intermediates that assist in coke elimination19–21.

More importantly, CH activation behavior plays an equally critical role in determining coke formation tendencies. Uncontrolled deep dehydrogenation of CH to carbon species, especially via the CH* → C* pathway, is a primary source of carbon deposition. Therefore, the rational design of catalysts should aim to precisely control CH decomposition pathways while enabling CO -derived oxygen species to actively participate in carbon oxidation. A key factor in this balance is the electronic structure of active metal sites, which governs CH adsorption and its subsequent activation. A moderately enriched electron density facilitates the initial C–H bond cleavage while suppressing excessive CH adsorption and deep dehydrogenation to CH* or C* species. Tailoring the support composition and interfacial architecture provides a promising pathway to optimize the surface electronic environment, achieve synergistic CH /CO activation, and improve the long-term stability of DRM catalysts. To explore how electronic and structural tuning of the support influences catalytic behavior in DRM, TiO and Al O were selected as representative oxide supports due to their distinct physicochemical characteristics. TiO , as a classical support for studying strong metal-support interactions (SMSI), readily generates oxygen vacancies under reducing conditions, which play a crucial role in CO activation and the oxidation of surface carbon species during DRM22,23. Compared with other reducible oxides such as CeO and ZrO , TiO offers a more cost-effective, tunable, and moderately reducible platform that enables controlled SMSI with Pt. This tunability enables controlled electron transfer at the metal-support interface, optimizing the Pt electronic state to balance CH activation and coke resistance24,25. However, TiO alone suffers from poor thermal stability and phase transformation at elevated temperatures, which may degrade catalytic performance. In contrast, Al O is a thermally stable, non-reducible oxide that provides a relatively electron-deficient environment, promoting CH activation and enables high initial activity. Yet, its lack of redox capability and oxygen vacancies makes it prone to carbon accumulation and rapid deactivation under DRM conditions.

In this study, we construct an atomically precise Pt/TiO -Al O interface through in situ growth of an ultra-thin anatase TiO overlayer on Al O . This tailored architecture enables the Al O support to exert long-range electronic control over Pt active sites via interfacial charge redistribution while eliminating Al O exposure that is favorable for carbon deposition. Combined analyses of XRD, GIXRD, XPS, CO-FTIR, in situ DRIFTS, and DFT calculations demonstrate that the interfacial structure formed between the anatase TiO overlayer and Al O effectively modulates the electronic state of Pt by suppressing excessive electron transfer from TiO , thereby maintaining an optimal adsorption for reactants. Importantly, DFT results show that the Pt/TiO -Al O catalyst increases the activation barrier for the CH*→C*, a key step in deep methane dehydrogenation leading to carbon formation, and effectively mitigates coke accumulation. Engineering electron transfer in ultra-thin anatase TiO overlayers on Al O offers a promising strategy for enhancing coke resistance and improving the long-term stability of Pt-based catalysts in the dry reforming of methane.

Results
Structure of catalysts

Structures of as-prepared Pt/A, Pt/T, and Pt/T-xA catalysts were well characterized. XRD patterns of reduced Pt/A, Pt/T, and Pt/T-xA catalysts were depicted in Supplementary Fig. 1. The diffraction peaks at 31.94°, 37.60°, 39.49°, 45.79°, 60.46° and 66.76° are assigned to γ-Al O (JCPDS 29-0063), The diffraction peaks at 25.28°, 37.8°, 48.05°, 53.89°, 55.06°, 62.69°, 68.76°, 70.31° and 75.03° are assigned to anatase TiO (JCPDS 21-1272)24. Additionally, with decreasing Ti content, the TiO diffraction peaks gradually diminish in intensity. When the Ti/Al ratio is 1:10, no characteristic diffraction peaks of TiO were observed, indicating that TiO is present in a highly dispersed state on the surface of Al O support25. For the reduced Pt/A and Pt/T-xA catalysts, the characteristic diffraction peaks of metallic Pt at around 39.8° (Pt(111)) and 46.2° (Pt(200)) coincide with the main diffraction peaks of γ-Al O . In the surface-sensitive GIXRD patterns (Supplementary Fig. 2), these Pt-related features appear as weak shoulder signals, indicating the presence of small, highly dispersed Pt nanoparticles.

To further elucidate the structural relationship between TiO and Al O , GIXRD was employed to enhance surface sensitivity. As shown in Supplementary Fig. 1, while no TiO diffraction peaks were detected for Pt/T-10A and Pt/T-20A catalysts in conventional XRD patterns, GIXRD revealed characteristic anatase TiO diffraction peaks in the Pt/T-10A catalyst, indicating the presence of an ultra-thin TiO layer on the surface of the Al O support. In contrast, no TiO signals were observed for the Pt/T-20NA catalyst, likely due to the TiO layer being too thin or poorly crystallized. The XPS sputtering results further confirmed this phenomenon (Supplementary Fig. 3 and Supplementary Table 1). Under the same sputtering conditions, the Al/Ti atomic ratio (Al2p/Ti2Tp) of the Pt/T-3A catalyst is almost unchanged, indicating that the TiO layer is thick. In contrast, the Al/Ti atomic ratios of the Pt/T-10A and Pt/T-20A catalysts is increasing.

The AC-HAADF-STEM images and the corresponding energy-dispersive X-ray spectroscopy (EDX) elemental mappings of the reduced Pt/T-10A catalyst were further carried out. AC-HAADF-STEM analysis (Fig. 1) reveals lattice fringes corresponding to the Pt (111) and Al O (311) planes, with interplanar spacings of 0.227 nm and 0.249 nm, respectively. However, no crystal planes corresponding to TiO were observed in the images, which is consistent with the XRD results. A slight decrease in the lattice clarity of Al O was observed in some regions, which may be associated with the presence of an ultra-thin TiO layer on the support surface (Supplementary Fig. 4). The thickness of the TiO layer is in the range of 2.6–3.6 nm (Supplementary Fig. 5a). EDX elemental mapping images showed the uniform distribution of Pt, Ti, Al, and O elements. The average Pt crystallite diameter of Pt/A and Pt/T-10A catalysts was determined by HAADF-STEM images (Supplementary Fig. 5 and 6), which indicates that the average particle size of the Pt/T-10A catalyst (1.01 nm) is smaller than that of the Pt/A catalyst (1.68 nm). This phenomenon may be attributed to the SMSI between Pt and TiO 26, which effectively inhibits the growth and agglomeration of Pt nanoparticles, leading to a more uniform dispersion and smaller particle size of the Pt nanoparticles. The N adsorption-desorption isotherms and pore size distribution of reduced Pt/A, Pt/T, and Pt/T-xA catalysts were shown in Supplementary Fig. 7, and their corresponding BET surface areas, pore diameters, and total pore volumes are summarized in Supplementary Table 2. Among these catalysts, Pt/T exhibited the lowest BET surface area, pore diameter, and volume. In contrast, the Pt/T-xA catalysts display significantly increased surface areas, which can be attributed to the high surface area of the Al O component. The enlarged surface area contributes to improved metal dispersion and better structural stability of the catalyst.

Surface and interface properties

To evaluate the reducibility of the as-prepared catalysts and the metal-support interaction, hydrogen temperature-programmed reduction (H -TPR) experiment was performed. As shown in Fig. 2a, the Pt/A catalyst showed a single reduction peak centered at 138 °C, which is mainly related to the reduction of PtO species. In contrast, the Pt/T and Pt/T-xA catalysts exhibited two reduction peaks in the range of 86–135 °C and 350–400 °C. The low-temperature reduction peak corresponds to the reduction of PtO species to metallic Pt0. The high-temperature reduction peak is primarily associated with the SMSI between Pt and TiO 23,27–29. As the Ti content increases, the low-temperature reduction peak gradually shifts to lower temperatures, indicating that the incorporation of TiO promotes the hydrogen spillover effect. This facilitates the migration of hydrogen species to the vicinity of PtO , thereby accelerating its reduction30. Meanwhile, the high-temperature reduction peak temperature gradually increases, and the temperature at the center of the peak reaches 400 °C for the Pt/T catalyst, indicating that the SMSI between Pt and TiO is enhanced. This enhanced interaction may lead to partial encapsulation of the Pt species by TiO , making its reduction more difficult31.

X-ray photoelectron spectroscopy (XPS) was used to analyze the surface composition and chemical states of elements. The XPS O1s spectra of the reduced Pt/T-xA and Pt/A catalysts were fitted with three binding energies at ~ 534.5, 532.9, and 531.2 eV, which correspond to the oxygen atoms of surface hydroxyl groups (O ), oxygen species adjacent to oxygen vacancies (O ), and lattice oxygen of the supports (O ), respectively (Fig. 2b)32,33. Electron paramagnetic resonance (EPR) spectroscopy was used to examine oxygen vacancies (Supplementary Fig. 8). In the reduced Pt/T-10A catalyst, a symmetrical signal with a g-value of 2.002 was detected, which is attributed to surface Ti3+ defects and superoxide radicals (O ⁻) bound to the surface, trapped by oxygen vacancies34. The relative fraction of oxygen species adjacent to oxygen vacancies, expressed as O /O (O = O + O ) increases from 5.8% to 7.5% with increasing Ti content (Supplementary Table 3). Among the catalysts, Pt/T-3A and Pt/T-10A catalysts have enhanced interfacial interaction between Pt and TiO . The XPS analysis of Ti 2p showed the presence of Ti4+ and Ti3+ in both the reduced Pt/T-10A catalyst and reduced T-10A support (Fig. 2c). Under the same reduction conditions, the Ti3+/Ti4+ ratio in the Pt/T-10A catalyst is higher than that in the T-10A support, indicating that the presence of Pt facilitates the partial reduction of TiO . This phenomenon may be attributed to SMSI between Pt and TiO , which promotes interfacial electron transfer and facilitates and release of lattice oxygen (O2⁻), thereby generating oxygen vacancies and leading to the partial reduction of Ti4+ to Ti3+ in the support. The Ti3+/Ti4+ ratio in all reduced catalysts ranges from 5.2% to 9.6%. (Fig. 2d) Notably, Pt/T-3A exhibits the highest Ti3+/Ti4+ ratio, indicating relatively SMSI, which may enhance the formation of oxygen vacancies and the reducibility of the support surface. To investigate the electronic environment surrounding Pt atoms, The XPS Pt 4d spectra reveals a systematic correlation between Ti content and the electronic structure of Pt nanoparticles (Fig. 2e). As the Ti content in the support increases, the Pt 4d binding energy exhibited a pronounced downward shift, indicative of a progressive enhancement in Pt electron density. This trend is attributed to the electron-donating effect of Ti3+ defects in TiO , which facilitate charge transfer to Pt via SMSI.

This electron transfer from TiO to Pt regulated by Al O is further corroborated by CO-FTIR spectroscopy (Fig. 2f). CO adsorbed on the Pt/A catalyst exhibited a sharp peak at 2069 cm-1 and a shoulder peak at 2090 cm-1, both corresponding to linearly adsorbed CO on Pt atoms. With increasing Ti content, a red shift in both peaks was observed. This shift is attributed to increased electron density of Pt, extracted from TiO species, which enhances the back-donation from its d-orbitals to the CO 2π* antibonding orbital, thereby weakening the C–O bond and lowering its vibrational frequency35. This observation aligns with the electronic structure changes revealed by XPS analysis and is further supported by TEM results, which showed smaller and more uniformly distributed Pt particles in the Pt/T-10A catalyst. Furthermore, the intensity of the CO adsorption peaks significantly decreased with increasing Ti content, suggesting a reduction in the available CO adsorption sites on the Pt surface. This phenomenon could be attributed to two possible factors: (1) the migration of TiO species may lead to partial coverage of Pt sites, thereby reducing the number of accessible CO adsorption sites25; (2) the electron transfer from TiO species to Pt increases the electron density of Pt, which may weaken CO adsorption36. However, the elevated electron density at Pt sites leads to a downshift of the d-band center, weakening the adsorption strength of CH intermediates and thereby impairing C–H bond activation efficiency37,38. The introduction of Al O provides a controlled electron-withdrawing effect, modulating the electronic state of Pt and mitigating electron over-saturation, as demonstrated by DFT calculations. The surface acid properties of Pt/T-10A and Pt/A were further characterized by NH -TPD (Supplementary Fig. 9), revealing the influence of Ti incorporation on the surface acidity. The detailed explanation is provided in Supplementary Information.

To investigate methane activation behavior and validate the electronic modulation induced by Al O , temperature-programmed surface reaction (CH -TPSR) experiments were conducted on Pt/T, Pt/T-10A, and Pt/A catalysts (Fig. 3). The results showed that the initial C-H bond cleavage temperatures for Pt/T, Pt/T-10A, and Pt/A catalysts were 323 °C, 313 °C, and 301 °C, respectively. Combined with XPS and CO-FTIR results, as well as theoretical analyses of Bader charge and d-band center, these findings suggest a correlation between the electronic environment of Pt and its ability to activate CH . Specifically, Pt/T catalyst showed the highest activation temperature, which is attributed to its electron-rich Pt state, resulting in weakened CH adsorption. In contrast, Pt/T-10A catalyst exhibited a moderately electron-rich Pt state, as the electron transfer from TiO to Pt is regulated by Al O , which effectively adjusts the electronic properties of Pt and lowers the activation barrier compared to Pt/T catalyst, while maintaining a more stable performance than Pt/A catalyst.

At temperatures below 600 °C, secondary products such as CO and H O were mainly derived from the interaction between CH intermediates and active oxygen species on the catalyst surface. In this process, surface oxygen or lattice oxygen from the support played a crucial role by oxidizing surface carbon species and promoting CO formation. As the temperature increased beyond 600 °C, the generation of CO significantly decreased, and methane primarily reacted with bulk oxygen through CH intermediates to produce H and CO39,40. The Pt/A catalyst exhibited stronger signals of CO, CO , H , and H O compared to the Pt/T-10A catalyst. This may be attributed to its d-band center being closer to the Fermi level, which promotes stronger adsorption and activation of methane on Pt sites. The CH intermediates species can subsequently react with surface or lattice oxygen on Al O , predominantly forming CO, with partial oxidation leading to CO . Due to the weaker oxygen donation capability of Al O , CO is more inclined to desorption41. Additionally, the increased H concentration may promote the reverse water-gas shift (RWGS) reaction, further generating CO and H O. In contrast, oxygen vacancies in the Pt/T-10A catalyst facilitate CO adsorption and activation, promoting the formation of stable carbonate species and consequently reducing the gas-phase CO signal. Furthermore, oxygen vacancies facilitated CO dissociation and the oxidation of CH intermediates. The dynamic regeneration of oxygen vacancies continuously supplies active oxygen species, maintaining catalytic activity.

Catalyst performance evaluations

To investigate the impact of interfacial electronic modulation induced by Al O on catalytic performance, the DRM tests of Pt/T, Pt/T-3A, Pt/T-10A, Pt/T-20A, and Pt/A catalysts were evaluated under reaction conditions of 700 °C with a CH /CO /N feed ratio of 30/30/30 mL min-1 for 20 h. The results were presented in Fig. 4a–c. Additional performance comparisons across a broader temperature range (600–800 °C) were provided in Supplementary Fig. 10. Among them, those supports containing TiO exhibit significantly better stability compared to Pt/A catalyst. A volcano-shaped activity-stability relationship for Pt/T-xA catalysts was governed by the interplay of Ti-mediated electronic and structural effects (Fig. 4d). Notably, Pt/T-10A catalyst demonstrated high stability, maintaining its initial conversion levels even after 20 h of reaction. In contrast, Pt/A catalyst showed the poorest stability, with methane and carbon dioxide conversions decreasing by 47.6% and 39.2% after reaction for 20 h, respectively. Additionally, the H /CO ratio for Pt/A catalyst dropped from 0.88 to 0.56 over the same period. This phenomenon is probably due to carbon deposition and sintering of Pt particles.

Compared to Pt/T catalyst, the interfacial structure between the TiO overlayer and the Al O support effectively modulates the electronic state of Pt by suppressing excessive electron donation from TiO . This regulation maintains an optimal electronic environment for the adsorption of reactants and reaction intermediates, thereby balancing CH activation and minimizing the risk of carbon accumulation. These effects are further supported by DFT calculations. Moreover, varying TiO loadings may influence the ability of Al O to modulate the electronic structure of Pt through the TiO layer. As indicated by GIXRD analysis, excessive TiO in the Pt/T-3A catalyst likely forms a thicker overlayer, thereby weakening the interfacial regulation of Al O . However, the lower TiO content in the Pt/T-20A catalyst is detrimental to reaction performance, likely because it cannot provide a sufficient interface. Concurrently, the presence of oxygen vacancies facilitates carbon removal. Together with the electronic modulation provided by Al O , these features synergistically enhanced carbon resistance and overall catalyst durability. To further evaluate the stability of the Pt/T-10A catalyst, a long-term stability test was conducted at 800 °C under a GHSV of 36000 mL h-1 g -1 for 100 h. As shown in Fig. 4e, the CH and CO conversions exhibited declines of approximately 4% and 1%, respectively.

Fig. 4f and Supplementary Table 4 comprehensively compare the catalytic performance of the catalyst developed in this study with oxide-based catalysts reported in the literature for the DRM reaction. Pt/T-10A catalyst exhibited high CH and CO conversions within the temperature range of 700–800 °C while maintaining a H /CO ratio close to 1. Under reaction conditions of 800 °C, Pt/T-10A catalyst achieved CH and CO conversions of 91% and 95%, respectively, with an H /CO ratio of 0.97. These values significantly outperform those of most Ni-based catalysts (e.g., Ni/CeO -Al O , Ni/Al O -La O ) as well as certain noble metal catalysts (e.g., Pt/Gd-CeO /Al O , Pt/CePr/Al O )42–46.

Additionally, Pt/T-10A catalyst exhibited a low deactivation rate constant (k = 4.25 × 10⁻3 h-1)47,48, which is significantly lower than those of Ni/TiO (k = 0.110 h-1) and Ni/CeO -Al O (k = 0.055 h-1), among other oxide-based catalysts. This indicates that Pt/T-10A catalyst maintains stable performance during long-term reactions. Furthermore, at a lower reaction temperature of 650 °C, Pt/T-10A catalyst maintained an H /CO ratio of 0.81, which suggests limited side reactions such as methane cracking or RWGS. In comparison, the Pt-Ni@CeO catalyst reported in the literature exhibits an H /CO ratio as low as 0.60 under similar conditions49.

Structural and carbon evolution of spent catalysts

To comprehensively evaluate the structural evolution and carbon formation behavior after DRM, XRD, TEM, XPS, TG, and Raman characterizations were performed on the spent catalysts. All catalysts were characterized after reaction at 700 °C for 20 h. The XRD characterization of the spent Pt/T catalyst revealed diffraction peaks corresponding to the rutile phase of TiO , indicating that rutile is the predominant crystalline phase (Fig. 5a). Phase transformation from the anatase phase to the rutile phase typically leads to a significant reduction in specific surface area, which negatively affects catalytic performance50. In contrast, for the Pt/T-xA catalysts, only the Pt/T-3A catalyst exhibited diffraction peaks corresponding to the anatase phase, and no characteristic peaks of the rutile phase were detected. Even after reacting at 800 °C for 100 h, no diffraction peaks corresponding to the rutile phase were detected for Pt/T-10A (Supplementary Fig. 11). This observation suggests that the addition of Al O significantly enhances the thermal stability of TiO , inhibiting the phase transformation at high temperatures. The suppression of this transformation may result from Al O limiting grain growth and stabilizing grain boundary structures24. For the Pt/A catalyst, its XRD pattern showed a distinct diffraction peak at 2θ = 26.3°, corresponding to the graphite carbon phase formed after the reaction51,52. The graphite carbon originates from the accumulation of carbon species generated during methane cracking on the catalyst surface. Excessive graphite carbon can block active sites, significantly suppressing catalytic performance. Moreover, the formation of graphite carbon is typically stable and challenging to reverse, potentially further reducing the long-term stability of the catalyst.

After the reaction at 700 °C for 20 h, the metallic Pt diffraction peaks became more apparent, indicating particle growth. HAADF-STEM confirmed that Pt/T-10A still contained a large population of Pt nanoparticles below 2 nm, with only a small fraction of larger crystallites. In contrast, Pt/A exhibited more uniformly grown particles with an average size of 3.54 nm (Supplementary Fig. 12). After the stability test at 800 °C for 100 h, pronounced Pt(111) signals appeared in the XRD pattern (Supplementary Fig. 11), indicating the presence of relatively larger Pt crystallites. HAADF-STEM analysis reveals that a dominant population of finely dispersed Pt nanoparticles is still retained (Supplementary Fig. 13 and Supplementary Table 5). The Pt crystallite size estimated from the Scherrer equation is 10.34 nm, while the volume-average particle diameter (D[4,3]) derived from STEM analysis is approximately 7.21 nm. This discrepancy likely arises because the Scherrer-derived XRD size reflects the largest Pt crystallites that produce resolvable diffraction peaks owing to their limited long-range order, whereas the volume-average diameter is mainly influenced by a small fraction of large particles within a broad size distribution. To directly quantify the accessible metal surface, CO chemisorption measurements were conducted. The results show that the accessible Pt surface area decreases slightly after the stability test, from 4.07 to 3.75 m2 g-1 (Supplementary Table 6), consistent with the sustained catalytic performance under DRM conditions.

An EDS line-scan analysis was performed on the spent catalyst (Supplementary Fig. 13b). The results revealed a strong spatial overlap between Pt and Ti distributions, whereas the Pt signal was relatively weak in regions rich in Al. This observation confirms that Pt species remained predominantly anchored on the TiO surface rather than directly on the Al O support, consistent with the AC-HAADF-STEM analysis discussed above. Such spatial consistency in Pt distribution suggests that the interfacial architecture between Pt and TiO -Al O was preserved during DRM. Furthermore, the XPS results of Pt/T-10A catalysts before and after DRM revealed that no discernible shift in the Pt 4d binding energies could be observed, while the Ti3+/Ti4+ ratio and O /O fraction remained nearly constant (Supplementary Fig. 14). These results indicate that the redox state of the TiO -Al O support and the interfacial electronic environment between Pt and the support were effectively preserved throughout the reaction, despite presence of moderate particle growth, thereby rationalizing the long-term stability of Pt/T-10A under high-temperature DRM conditions.

TGA has been performed to quantify the amount of carbon formed during the 20 h reaction, as shown in Fig. 5b and Supplementary Table 7. All catalysts exhibited weight loss below 100 °C, primarily attributed to the desorption of physically adsorbed water. Increasing the Ti content led to a gradual reduction in the weight loss of the catalysts, suggesting that the incorporation of TiO improved their resistance to carbon deposition53. The TGA results showed that the Pt/T catalyst had the least weight loss (0.33%). In contrast, the Pt/A catalyst exhibited the greatest weight loss (5.90%), indicating more pronounced carbon deposition, which could adversely affect its long-term stability.

Raman spectroscopy provides detailed structural information on carbon species with different degrees of order. As shown in Fig. 5c, the D-band at 1342 cm-1 is associated with the defects or disordered vibrations of sp2-hybridized carbon, while the G-band at 1590 cm-1 corresponds to the planar vibrations of graphitized sp2 carbon. Therefore, the intensity ratio of the D-band to the G-band (I /I ) is commonly used as a key indicator for assessing the degree of graphitization in carbon materials13,54. Experimental results (Supplementary Table 7) indicated that the I /I value of the Pt/A catalyst (0.91) is significantly lower than that of Pt/T-10A (1.53), suggesting a higher degree of graphitization for the carbon species on the Pt/A catalyst.

Coke resistance mediated by activated lattice oxygen

To further probe the surface reaction mechanism and the nature of intermediate species during DRM, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were conducted over a temperature range of 50 °C to 600 °C (Fig. 6). To gain deeper insights into the reaction mechanism, the in situ DRIFTS experiments were conducted in three steps: (i) feeding CH gas alone; (ii) feeding CO gas alone; and (iii) feeding both CH and CO gas.

During the methane adsorption process, in situ DRIFTS in the range of 1100–2700 cm⁻1 were collected to investigate potential intermediates involved in the adsorption and reaction, as shown in Fig. 6a and b. Several characteristic absorption peaks reveal the presence of various surface-adsorbed species and their interactions with the catalyst. The peak at 1304 cm⁻1 corresponds to gaseous CH , while the peak at 1342 cm⁻1 is associated with partially dissociated CH * intermediates (x = 1–3)55. Peaks at 1460 cm⁻1, 1568 cm⁻1, and 1643 cm⁻1 are assigned to monodentate carbonate (m-CO 2⁻), bidentate carbonate (b-CO 2⁻), and bicarbonate species, respectively56–58. Additionally, the peak at 2040 cm⁻1 is linked to linearly adsorbed CO on the catalyst surface, and the peak at 2335 cm⁻1 corresponds to CO adsorption59–61. Under CO -free conditions, carbonate species may be generated from the reaction between surface hydroxyl groups of the catalyst and CH * intermediates, where the formed bicarbonate decomposes into carbonate at high temperatures. Another possible formation mechanism involves the activation of CH * intermediates by active lattice oxygen, leading to the generation of CO , which subsequently interacts with surface metal cations to form stable carbonate species. Compared to the Pt/A catalyst, the relative intensity of carbonate species is higher on the Pt/T-10A catalyst, which may be closely related to the presence of oxygen vacancies and their derived active oxygen species. These oxygen vacancies and active oxygen species further facilitate the activation and reaction of CH intermediates, resulting in the formation of more stable carbonate species. Additionally, the bidentate carbonate species formed on the Pt/T-10A catalyst exhibit a more stable coordination structure, which promotes their further reaction with coke intermediates62–64. At temperatures above 450 °C, a significant CO desorption peak was observed on the Pt/T-10A catalyst, whereas only a weak signal was detected on the Pt/A catalyst. This phenomenon can be attributed to the synergistic effect of oxygen vacancies and lattice oxygen in the Pt/T-10A catalyst. Specifically, oxygen vacancies facilitate the activation of methane-derived CH * intermediates, promoting their further oxidation to CO . The generated CO may also be temporarily captured by oxygen vacancies, forming stable adsorbed species. Meanwhile, the oxygen vacancies in the Pt/T-10A catalyst can dynamically regenerate lattice oxygen through interactions with surface or bulk oxygen, maintaining continuous oxidation of CH * intermediates. In contrast, the Pt/A catalyst lacks a similar mechanism for oxygen vacancy or lattice oxygen regeneration, limiting its ability to oxidize CH * intermediates. Once the lattice oxygen on the catalyst surface is depleted, it cannot be replenished through a dynamic process, leading to the accumulation of CH * intermediates and subsequent coke formation. This observation aligns with the results of the CH -TPSR experiment, where the Pt/T-10A catalyst demonstrated a stronger resistance to coke accumulation and higher oxidation efficiency compared to the Pt/A catalyst.

In situ DRIFTS were obtained during CO adsorption for the range of 1200–1800 cm−1, corresponding to the formation of species in strong CO chemisorption, as shown in Fig. 6c and d. The band at 1443 cm⁻1 is generally associated with monodentate carbonate species, whereas those at 1354 cm⁻1 and 1570 cm⁻1 are linked to bidentate carbonate species. The features observed at 1228 cm⁻1 and 1655 cm⁻1 are ascribed to bicarbonate species65,66. The relative intensities of the adsorption peaks corresponding to monodentate and bidentate carbonates on the Pt/T-10A catalyst were significantly higher than those on the Pt/A catalyst. On the Pt/A catalyst, no signals of bidentate carbonates were detected. The formation of bidentate carbonates originates from the synergistic interaction of CO molecules with two adjacent active sites on the catalyst surface, such as metal cations and oxygen vacancies. This coordination mode endows bidentate carbonates with higher binding energy and thermal stability, which helps to prolong the residence time of CO and facilitates the storage of active oxygen species62,67,68. In contrast, monodentate carbonates interact with CO through isolated active sites, exhibiting higher reactivity and promoting the rapid conversion of CO 69. As the temperature increased, the Pt/A catalyst primarily exhibited the gradual depletion of bicarbonates, and simultaneous decomposition of monodentate carbonates and bicarbonates was observed above 400 °C. By comparison, the adsorption peak intensities of carbonates on Pt/T-10A remained relatively unchanged, indicating that the existence of TiO significantly enhances the adsorption and stability of carbonate species by increasing the density of oxygen vacancies. Oxygen vacancies not only provide additional binding sites for CO adsorption but also maintain the activity of surface lattice oxygen through a dynamic regeneration mechanism, thereby suppressing the premature desorption of CO at high temperatures. These structural and electronic features endow the Pt/T-10A catalyst with enhanced coke resistance and catalytic activity.

Besides, in the in situ DRIFTS under DRM conditions (Supplementary Fig. 15), the absorption peak at 2341 cm⁻1 is attributed to the adsorption of CO , while the absorption peak at 3016 cm⁻1 corresponds to the adsorption of CH 70. The vibrational signals of CH * species gradually weaken as the reaction temperature increases. Methane adsorbs on Pt active sites and undergoes stepwise dissociation to form CH * (x = 1–3) and H* reactive intermediates. Simultaneously, CO is adsorbed on the catalyst surface in the form of carbonates and reacts with CH * species to produce syngas (CO and H ). The increase in temperature accelerates the dissociation of CH and the activation of CO , thereby enhancing the syngas production rate.

Mechanism for overcoming the activity-stability trade-off in Pt/TiO -Al O

In order to further reveal the essential reason why Pt/TiO -Al O maintains high activity and stability from the perspective of catalyst structure and properties, density functional theory (DFT) calculations were performed to reveal the electronic regulation between Pt and TiO induced by Al O . Pt cluster on three supports (TiO (001), TiO (001)-Al O (100) and Al O (100)) were built to simulate structures of Pt/T (Pt /TiO (001)), Pt/T-10A (Pt /TiO (001)-Al O (100)) and Pt/A (Pt /Al O (100)), respectively (Supplementary Fig. 16). Bader charge calculation reveals that the Pt cluster carry negative charges of –0.79 |e| and –0.16 |e| in the Pt /TiO (001) and Pt /TiO (001)-Al O (100) models71,72, respectively, whereas it exhibits a positive charge (+ 1.24|e|) in the Pt /Al O (100) model (Supplementary Table 8). These findings were consistent with XPS and CO-DRIFTS results. To further elucidate the structure–electronic synergy induced by Al O , we performed structural optimization and Bader charge analyses of the representative Pt atoms and their directly coordinated oxygen atoms (Supplementary Fig. 17). In the Pt /TiO (001)-Al O (100) model, the average Ti–O bond length was 1.92 Å, slightly shorter than that in the Pt /TiO (001) model (1.95 Å) (Supplementary Fig. 18 and Supplementary Table 9). This contraction originates from interfacial strain, which induces lattice shrinkage of the TiO overlayer, thereby strengthening Ti–O bonding and enhancing the reactivity of lattice oxygen. Compared with the Pt /TiO (001) model, the interfacial oxygen atoms (Ti–O–Al) in the Pt /TiO (001)-Al O (100) system exhibited a higher electron density (–1.08 |e| vs –1.02 |e|). Meanwhile, the interfacial oxygen facilitated electron transfer from Al O to Ti, alleviating the electron depletion of Ti ions (interface Ti: +1.84 |e| vs +1.93 |e| in pure TiO ). As a consequence, the electron donation from TiO to Pt was weakened. Correspondingly, the Pt atoms shifted from an electron-enriched state (–0.13 |e|) to a mildly electron-deficient state (+0.14 |e|).

To gain deeper insights into the influence of electronic structure on catalytic behavior, the projected density of states (pDOS) of Pt d orbitals in Pt /TiO (001), Pt /TiO (001)-Al O (100), and Pt /Al O (100) models was calculated, as shown in Fig. 7b. The d-band center of the Pt cluster of Pt /TiO (001) exhibits the lowest d-band center (–2.16 eV), which gradually shifts upward to –1.60 eV in Pt /TiO (001)-Al O (100) and further to –1.27 eV in Pt /Al O (100). An upward shift in the d-band center indicates that the Pt d orbitals move closer to the Fermi level, thereby raising the energy of the antibonding states formed with adsorbates, reducing their electron occupancy, and facilitating stronger adsorption and activation73,74. The d-band center of the Pt cluster in Pt /TiO (001)-Al O (100) lies between Pt /Al O (100) and Pt /TiO (001), leading to a compromise in adsorption strength for adsorbates. This optimized structure is beneficial to preventing carbon deposition due to excessive adsorption.

Subsequently, the adsorption behaviors of the reactant and intermediates on the surfaces of Pt /TiO (001), Pt /TiO (001)-Al O (100), and Pt /Al O (100) were investigated. The corresponding adsorption configurations and adsorption energies are presented in Supplementary Fig. 19–21, Supplementary Table 10, and Fig. 7a. The results showed that CH adsorption was strongest on Pt /Al O (100) (–0.39 eV), weakest on Pt /TiO (001) (–0.14 eV), and intermediate on Pt /TiO (001)-Al O (100) (–0.23 eV). Regarding the adsorption of intermediates, Pt /Al O (100) exhibited stronger binding with CH *, CH *, and CH* species, whereas Pt /TiO (001) showed the weakest adsorption overall, suggesting poor stabilization of dehydrogenated intermediates. Notably, Pt /TiO (001)-Al O (100) exhibits intermediate adsorption strengths toward these species, consistent with the trend observed in the d-band center analysis.

Fig. 7c illustrated the energy barrier profiles for the stepwise dehydrogenation of CH * to C* on the Pt /TiO (001), Pt /TiO (001)-Al O (100), and Pt /Al O (100) model surfaces. In these systems, CH first adsorbs onto the Pt cluster sites, followed by successive C–H bond cleavage steps to form CH *, CH *, CH*, and eventually C* species (Supplementary Fig. 22). Specifically, on the Pt /Al O (100) surface, the intrinsic activation energy for the initial C–H bond cleavage of CH is 0.23 eV, and the subsequent barriers for CH * → CH *, CH * → CH*, and CH* → C* steps are 0.33, 0.10, and 0.48 eV, respectively. In contrast, on the Pt /TiO (001) surface, although the first C–H bond cleavage remains facile ( 0.22 eV), the CH * → CH * step faces a substantially increased barrier (1.35 eV). The subsequent CH * → CH* and CH* → C* steps also encounter high barriers (0.63 and 1.12 eV, respectively). The higher dehydrogenation barrier of CH and intermediates on Pt/TiAO explains its lower initial activity than that of Pt /Al O (100).

Notably, on the Pt /TiO (001)-Al O (100) surface, the activation energy for the first C–H bond cleavage remains low (0.24 eV), the energy barriers for the CH * → CH *, CH * → CH*, and CH* → C* steps increased significantly to 0.87, 0.34, and 0.82 eV, respectively. This indicated that the Pt sites modulated by the TiO -Al O interface can retain initial activity while substantially suppressing deep dehydrogenation. Taken together with the structural and Bader charge analyses, the dual effects of strain-induced lattice contraction and interfacial oxygen-mediated charge redistribution by Al O both activate TiO lattice oxygen to suppress carbon deposition and optimize the electron density of Pt clusters, delivering a balanced trade-off between activity and coke resistance on Pt /TiO (001)-Al O (100).

To further clarify the role of oxygen species generated from CO dissociation in carbon oxidation, we calculated the energy barriers for CO dissociation and the subsequent C–O coupling reactions on Pt /TiO (001)-Al O (100) and Pt /Al O (100) models (Supplementary Fig. 23). In the Pt /TiO (001)-Al O (100) model, the O atom released from CO dissociation at an interfacial Pt site preferentially fills an oxygen vacancy on the TiO surface, forming lattice oxygen. A lattice oxygen atom located near the interface can then react with a neighboring C* to produce CO, while simultaneously regenerating the oxygen vacancy, thereby establishing a dynamic cycle between oxygen vacancies and lattice oxygen, which resembles a Mars-van Krevelen-type oxidation mechanism75. In contrast, in the Pt /Al O (100) model, the O atom produced from CO dissociation directly oxidizes the surface C* to form CO.

The calculated activation barriers for CO dissociation and the subsequent oxidation step on Pt /TiO (001)-Al O (100) are 0.66 eV and 0.97 eV, respectively, which are significantly lower than those on Pt /Al O (100) (0.88 eV and 1.91 eV). Combined with the in situ DRIFTS results, these findings suggest that the dynamic cycle between oxygen vacancies and lattice oxygen enables continuous regeneration of active oxygen species during the reaction, thereby promoting the oxidation of carbon deposits. This beneficial behavior is attributed to the ultra-thin anatase TiO overlayer, which provides accessible vacancies together with mobile lattice oxygen.

Methods
Catalyst preparation

The TiO and TiO -Al O supports were synthesized through a one-pot hydrothermal method. Under magnetic stirring, Tetrabutyl titanate [Ti(OC H ) , TBT] was added to a solution containing glycerol and ethanol, followed by the addition of an appropriate amount of Al O . After stirring for 1 h, the solution was transferred to a 100 mL Teflon-lined autoclave and heated at 180 °C for 24 h. The resulting white powder was then collected, washed several times with anhydrous ethanol, and dried overnight at 60 °C. Finally, the powder was calcined at 400 °C for 1 h with a heating rate of 5 °C min-1. The nominal molar ratios utilized were TBT/glycerol/ethanol = 1:100:60. The solids prepared were named T-xA, where x is the atomic ratio of Al O /TiO . In this experiment, four supports, T, T-3A, T-10A, and T-20A, were prepared separately.

The Pt catalysts were prepared by incipient wetness impregnation (IWI) using Al O , TiO , or T-xA as supports. Chloroplatinic acid hexahydrate (H PtCl ·6H O, Pt content 37%) was used as the Pt precursor. Prior to impregnation, the pore volume of each support was determined by measuring its saturated water uptake. The resulting pore volumes were 0.83, 1.62, 1.80, 1.72, and 1.74 mL g-1 for TiO , T-3A, T-10A, T-20A, and Al O , respectively. For each catalyst, 1 g of support and an aqueous H PtCl ·6H O solution with a concentration of 100 mg mL-1 were employed. To achieve a nominal platinum loading of 3 wt% (Supplementary Fig. 24), 835 μL of the H PtCl ·6H O solution was first transferred into a 5 mL centrifuge tube, followed by the addition of deionized water to adjust the total solution volume to match the pore volume of the corresponding support. Specifically, additional water volumes of 785, 965, 885, and 905 μL were added for T-3A, T-A10A, T-20A, and Al O , respectively. The resulting solutions were ultrasonicated for 10 min until a homogeneous solution was obtained. The impregnation solution was then added dropwise to the support under continuous manual stirring with a glass rod to ensure uniform distribution of the precursor throughout the pore network. After impregnation, the samples were kept under static conditions at room temperature for 2 h. The impregnated solids were subsequently dried in a vacuum oven at 80 °C for 10 h, followed by calcination in a muffle furnace at 350 °C for 2 h with a heating rate of 2 °C min-1 under static air. The resulting catalysts were denoted as Pt/A, Pt/T, and Pt/T-xA, respectively.

Catalytic characterization

The reduced, fresh, and spent catalysts were characterized by using X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), and high-angle annular dark field scanning transmission electron microscopy (AC-HAADF-STEM). The specific area and pore’s structure were obtained by nitrogen adsorption-desorption techniques on Micromertics ASAP 2460. H temperature-programmed reduction (H -TPR), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), the DRIFTS experiments of CO adsorption (CO-DRIFTS), NH temperature programmed desorption (NH -TPD), thermogravimetric analysis (TGA), and Raman. For the DRM mechanism study, the temperature-programmed surface reaction of methane (CH -TPSR), in situ DRIFTS was conducted. The details of characterization techniques and procedures, including the DFT method, are given in Supplementary Information.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "Dry reforming of methane is an effective way to convert the two main green house gases to syngas, which could be used in future chemical processes, showing promise to mitigate global warming. In this manuscript, the authors constructed a well-defined Pt/TiO2-Al2O3 interface by depositing an ultra-thin anatase TiO2 overlayer onto Al2O3 via an in situ growth strategy to eliminate detrimental Al2O3 exposure. The as-prepared catalysts were characterized by a number of modern techniques. The optimized Pt/TiO2-Al2O3 catalyst achieved exceptional durability, maintaining 91% CH4 conversion at 800 °C for 100 h with negligible carbon deposition, and the origin of the good performance were correlated to the structural features of the catalyst. My suggestions are the followings:\n1. In the part of “Introduction”, the authors are suggested to comment shortly the main advances of Ni based catalysts which are more commonly studied since Ni is much cheaper, then the choice of Pt as the main active component of the catalyst could be elaborated.\n2. The use of abbreviation should be firstly defined. For example, line 97, “TBT” is directly used without definition.\n3. The details of the reduction processes for the samples before characterization should be provided.\n4. Lines 130-131, please check the logic of the statement, “In contrast, no TiO2 signals were observed for the Pt/T-20A catalyst, likely due to the TiO2 layer being too thin or insufficient to fully cover the Al2O3 surface.”, considering the fact that even if crystal TiO2 were formed, one could not deduce if the Al2O3 surface was fully covered. Similar statements should be carefully checked. Such as, lines 141-143, “We observed that the lattice clarity of Al2O3 decreases in areas where Pt nanoparticles grow, which may be related to an ultra-thin TiO2 layer on the surface of the Al2O3 support.”, why Pt nanoparticles could not grow on the surface of the Al2O3 support to make the lattice clarity of Al2O3 decreases?\n5. Please distinguish in a more clear way the “low-coordinated defect oxides (OV),” and “oxygen vacancies”, especially when discussing the O1s XPS results. O1s XPS peak could not be directly assigned to “oxygen vacancies”, since the later means “no O present”, whereas O1s XPS peak was originated from the interaction of X-ray with the O1s orbital.\n6. The authors are suggested to compare the structural variation of the catalysts before and after the DRM to correlate further the structure-performance relationship.\n7. The authors are suggested to consider the fact, the support material was calcined finally at 400 °C, the catalyst precursors were calcined at 350 °C, and the catalyst samples were reduced at 400 °C before catalytic performance evaluation at 600-800 °C. Are there any structural variation under different temperature conditions?\n8. Th optimized catalytic performance under optimized conditions were “CH4 and CO2 conversions of 91% and 95%, respectively, with an H2/CO ratio of 0.97.”, which is only quite close to complete conversion of the reactants, limiting the further utilization of the syngas obtained. How could one get higher conversion of the reactants by using the optimized catalyst?\n9. Proof reading needs to be carefully checked. For example, line 90, “the activation barrier for the 1, a”, the meaning of “1” here is not clear.", "reviewer_2": "Review of Liu et al.\nThe authors have developed an interesting synthesis of titania-coated alumina which is claimed to promote dry reforming reactivity by activating the lattice oxygen in the thin titania layers and improve Pt durability by optimizing Pt charge density. There is a major problem which undercuts the main conclusions of the paper; the authors have turned a blind eye toward crystalline Pt in XRD patterns. This is most evident in Figure S6, in which the Pt(111) and (200) peaks at 39.8 and 46.2 degrees 2theta are mis-identified as alumina. There is indeed a (222) peak of gamma alumina at 39.2 degrees 2theta, but the intensity of this peak is much lower that the peak which appears in the data. Comparison with a pure gamma alumina control sample would have made this clear. Secondly, in Figure S6 both peaks in the range of 45-46 degrees 2theta are attributed to gamma alumina, when gamma alumina does not have two peaks in this region (this can be seen from the gamma alumina PDF reference shown in Figure S1. The second peak is most certainly Pt(200) at 46.2 degrees 2theta. The sharp Pt peaks present in Figure S6 arise from relatively large Pt nanoparticles, and these are actually imaged in the STEM images of Figure S7, but this connection is never made! In like manner, in the Pt/T-20A diffractogram in Figure S1, the Pt(111) peak is again clearly seen, and the Pt(200) peak can be seen as a right hand shoulder on the 45 degree 2theta peak. Once again in Figure 5a for the 20 h reacted catalysts, crystalline (111) and (200) Pt peaks prominently appear for 10A, 20A, and A catalysts but are not identified as such. In fact, there is clearly crystalline Pt seen in Figure 1a in the P/T-20A sample, and perhaps also the P/T-10A sample.\nThe extensive sintering of the P/T-10A sample calls into question the claims for enhanced stability, as well as the suitability of 5-atom Pt clusters to represent the Pt phase in the simulations. The faulty interpretation of XRD data must be corrected. The conclusions must be reimagined and brought into alignment with accurate characterization. Obtaining diffractograms of pure gamma alumina as an XRD control sample will help interpret the results.", "reviewer_3": "I. Introduction\n1. P39, the authors should explain why DRM has higher energy efficiency compared to SMR and POX.\n2. P47, an important fraction of the deposited carbon is generated on highly active Ni(110) sites; therefore, alloying Ni with other metals could help reduce deactivation. Such a strategy should be mentioned.\n3. P57, indeed, CH* → C* is an essential pathway for coke formation. However, this route also exists in SMR, where coke deposition is well controlled by providing sufficient oxidant from steam. Therefore, the dissociation of CO₂ to O* plays a key role in burning coke. I suggest that these pathways be studied at least at the DFT level.\n4. P69, Since TiO₂ is a reducible metal oxide, the authors should provide stronger justification for its selection, particularly given that CeO₂ can also undergo partial reduction.\nII. Materials and Methods\n2. P107, the authors should clarify why a loading of 3 wt% Pt was selected, given that typical Pt loadings are below 1 wt%. This value seems unusually high for such a precious metal. In addition, the rationale for choosing Pt over Ni should be explained.\nIII. Results and Discussion\n1. P160, Figure 1. The XRD patterns and N₂ adsorption–desorption isotherms should be presented separately and in an expanded form.\n2. P321/322, please provide references regarding the deactivation rates of the mentioned catalysts.\n3. P369 and Table S5(SI), The authors reported weight loss but did not specify how it was calculated. It is highly recommended to present the corresponding TGA curves.\n4. P475, the authors should justify their choice of a Pt₅ cluster to represent Pt nanoparticles.\n5. The authors should address the oxidation pathway associated with O species generated from CO₂ dissociation.\n6. The acidity of the supports can catalyse the successive dehydrogenation of methane. The authors are requested to clarify why this important parameter was neglected in their discussion."}, "author_response": "Point-by-point responses to reviewers’ comments for “Modulation of Pt Electron Transfer via Engineered Ultra-Thin TiO -Al O Interfaces for Coke-Resistant Methane Dry Reforming” (NCOMMS-25-66180)\nReviewer #1:\nDry reforming of methane is an effective way to convert the two main green house gases to syngas, which could be used in future chemical processes, showing promise to mitigate global warming. In this manuscript, the authors constructed a well-defined Pt/TiO -Al O interface by depositing an ultra-thin anatase TiO overlayer onto Al O via an in situ growth strategy to eliminate detrimental Al O exposure. The as-prepared catalysts were characterized by a number of modern techniques. The optimized Pt/TiO -Al O catalyst achieved exceptional durability, maintaining 91% CH conversion at 800 °C for 100 h with negligible carbon deposition, and the origin of the good performance were correlated to the structural features of the catalyst. My suggestions are the followings:\nComment 1:\nIn the part of “Introduction”, the authors are suggested to comment shortly the main advances of Ni based catalysts which are more commonly studied since Ni is much cheaper, then the choice of Pt as the main active component of the catalyst could be elaborated.\nResponse:\nWe sincerely thank you for the constructive suggestion. We have added a short discussion in the Introduction section. The revised paragraph now reads as follows.\nLine 55-63 on Page 3-4:\nNi-based catalysts are widely studied due to their high CH activation ability and 4 low cost. To improve their long-term stability in DRM, strategies such as introducing promoters, alloying Ni with other metals, and constructing confinement structures have been explored9-12. However, the inherent tendency of Ni to promote carbon formation and to undergo sintering under DRM conditions remains a major limitation for achieving long-term durability. In contrast, noble metals such as Pt generally exhibit a much higher intrinsic resistance to carbon deposition, which allows for a clearer investigation of coke suppression and interfacial reaction mechanisms under harsh reforming conditions1.\nAccordingly, four new references [9-12] have been cited:\n9. Cheng, F., Duan, X. & Xie, K. Dry reforming of CH /CO by stable Ni nanocrystals 4 2 on porous single-crystalline MgO monoliths at reduced temperature. Angew. Chem. Int. Ed. 60, 18792–18799 (2021).\n10. Johnson, O. et al. Stabilizing catalytic performance in dry reforming of methane via surface-engineered intermetallic carbide nanoparticles. J. Am. Chem. Soc. 147, 16786–16791 (2025).\n11. Wang, Q. et al. Interface engineering of oxygen-vacancy-rich MgO/Ni@NiAlO enables low-temperature coke-free methane dry reforming. Chin. J. Catal. 75, 9–20 (2025).\n12. He, D. et al. Designing ultra-stable and surface-exposed Ni nanoparticles with dually confined microenvironment for high-temperature methane dry reforming. Adv. Funct. Mater. 35, 2412895 (2025).\nComment 2:\nThe use of abbreviation should be firstly defined. For example, line 97, “TBT” is directly used without definition.\nResponse:\nWe sincerely thank you for carefully pointing out this mistake. We have corrected it in the “Catalyst preparation” section of the revised manuscript.\nLine 615 on Page 32:\n“Under magnetic stirring, Tetrabutyl titanate [Ti(OC H ) , TBT] was added to ……” 4 9 4\nComment 3:\nThe details of the reduction processes for the samples before characterization should be provided.\nResponse:\nWe sincerely thank you for this helpful comment. The other characterization methods, including the in situ reduction procedures, were already described in the manuscript (Line 58-102 on Page 4-6 in Supplementary Information). We have now carefully supplemented the reduction procedure applied for XRD, GIXRD, TEM, AC-HAADF-STEM, BET, XPS and EPR characterization.\nLine 45-50 on Page 3 in Supplementary Information:\nFor XRD, GIXRD, TEM, AC-HAADF-STEM, BET, XPS and EPR characterizations, the catalysts were reduced in a fixed-bed reactor under a 10% H /N 2 2 gas mixture (40 mL·min-1). The temperature was ramped at 10 °C·min-1 to 400 °C and held for 1 h. The other characterizations (NH -TPD, CH -TPSR, CO-DRIFTS, and in situ DRIFTS) were conducted with in situ pretreatment steps, and the reduction procedures are described in the experimental section.\nComment 4:\nLines 130-131, please check the logic of the statement, “In contrast, no TiO signals were observed for the Pt/T-20A catalyst, likely due to the TiO layer being too thin or insufficient to fully cover the Al O surface.”, considering the fact that even if crystal TiO were formed, one could not deduce if the Al O surface was fully covered. Similar statements should be carefully checked. Such as, lines 141-143, “We observed that the lattice clarity of Al O decreases in areas where Pt nanoparticles grow, which may be related to an ultra-thin TiO layer on the surface of the Al O support.”, why Pt nanoparticles could not grow on the surface of the Al O support to make the lattice clarity of Al O decreases?\nResponse 4-1:\nThe reviewer raises a good point. We agree with your concerns and have carefully revised the relevant statements in both the “Structure of catalysts” and “Catalyst performance evaluations” sections.\nLine 135-136 on Page 7:\nIn contrast, no TiO signals were observed for the Pt/T-20A catalyst, likely due to the TiO layer being too thin or poorly crystallized. 2\nLine 307-308 on Page 16:\nHowever, the lower TiO content in the Pt/T-20A catalyst is detrimental to reaction performance, likely because it cannot provide a sufficient interface.\nResponse 4-2:\nWe re-examined the HRTEM images of the Pt/A catalyst to clarify the origin of the reduced lattice contrast. In the Pt/A catalyst, the Al O lattice underneath the Pt nanoparticles remains clearly resolved, indicating that the presence or growth of Pt nanoparticles does not diminish the crystallinity of the Al O support. This observation aligns with previous reports showing that even when Pt is concentrated at the interface in a highly dispersed or quasi-atomic form, the lattice structure of Al O remains unaffected1. Therefore, the locally reduced lattice contrast observed in Pt/T-10A is more plausibly attributed to an amorphous or ultra-thin TiO layer rather than to Pt nanoparticle growth. To avoid potential ambiguity, we have revised the statement as follows in the “Structure of catalysts” and Supplementary Information section.\nReference\n1. Li, S. et al. Strong oxide-support interaction induced thermal stabilization of Pt single atoms for durable catalytic CO oxidation. Angew. Chem. Int. Ed. 64, e202504551 (2025).\nLine 147-149 on Page 8:\nA slight decrease in the lattice clarity of Al O was observed in some regions, which may be associated with the presence of an ultra-thin TiO layer on the support surface (Supplementary Fig. 4).\nLine 179-185 on Page 11 in Supplementary Information:\nSupplementary Figure 4. HRTEM image of reduced Pt/A.\nHRTEM images of the Pt/A catalyst showed that the Al O lattice remains well resolved directly beneath Pt nanoparticles. This confirms that the reduced lattice clarity observed in some regions of Pt/T-10A is not caused by Pt deposition but is more plausibly related to the presence of an amorphous or ultra-thin TiO layer on the Al O surface.\nComment 5:\nPlease distinguish in a more clear way the “low-coordinated defect oxides (O ),” V and “oxygen vacancies”, especially when discussing the O1s XPS results. O1s XPS peak could not be directly assigned to “oxygen vacancies”, since the later means “no O present”, whereas O1s XPS peak was originated from the interaction of X-ray with the O1s orbital.\nResponse:\nWe sincerely thank you for the insightful comment and for pointing out the conceptual inaccuracy regarding the distinction between “low-coordinated defect oxides” and “oxygen vacancies”. In the literature, several terms have been used to describe the higher-binding-energy O 1s features, including “oxygen species adjacent to oxygen vacancies”1,2, “defect oxide with a low coordination”3, and “oxygen vacancies”4,5,6. After carefully reviewing these descriptions, we consider “oxygen species adjacent to oxygen vacancies” to be the most accurate terminology for the O 1s component observed in our catalysts.\nReference:\n1. Fu, X.-P. et al. Boosting reactivity of water-gas shift reaction by synergistic function over CeO /CoO /Co dual interfacial structures. Nat. Commun. 14, 6851 2-x 1-x (2023).\n2. Wang, Q. et al. Operando investigation of toluene oxidation over 1D Pt@CeO 2 derived from Pt cluster-containing MOF. J. Am. Chem. Soc. 143, 196–205 (2021).\n3. He, Z. et al. Engineering an Ni-TiO interface for highly active and durable solar- x driven dry reforming of methane. Chem Catal. 4, 101040 (2024).\n4. Ren, X. et al. Boosting the activity in the liquid-phase hydrogenation of s- containing nitroarenes by dual-site Pt/CeO catalysts design. Nat. Commun. 16, 4851 2 (2025).\n5. Wang, H. et al. Facilitating the dry reforming of methane with interfacial synergistic catalysis in an Ir@CeO catalyst. Nat. Commun. 15, 3765 (2024).\n6. Gong, C. et al. Construction of active Rh-TiO interfacial sites on RhFeO /P25 for x x highly efficient hydrogenation of CO to ethanol. ACS Catal. 14, 17582–17597 (2024).\nWe have revised the description in the “Surface and interface properties” section and updated the corresponding literature citations for greater clarity. The revised text now reads as follows.\nLine 191-192 on Page 10:\n“oxygen species adjacent to oxygen vacancies (O ), and lattice oxygen of the V supports (O ), respectively (Fig. 2b)32,33.” L\nLine 196-198 on Page 10:\nThe relative fraction of oxygen species adjacent to oxygen vacancies, expressed as O /O (O = O + O ) increases from 5.8% to 7.5% with increasing Ti content V A A L H (Supplementary Table 3).\nAccordingly, two new references [32, 33] have been cited:\n32. Fu, X.-P. et al. Boosting reactivity of water-gas shift reaction by synergistic function over CeO /CoO /Co dual interfacial structures. Nat. Commun. 14, 6851 2-x 1-x (2023).\n33. Wang, Q. et al. Operando investigation of toluene oxidation over 1D Pt@CeO 2 derived from Pt cluster-containing MOF. J. Am. Chem. Soc. 143, 196–205 (2021).\nComment 6:\nThe authors are suggested to compare the structural variation of the catalysts before and after the DRM to correlate further the structure-performance relationship.\nResponse:\nWe thank you for this insightful suggestion. In the revised manuscript, we have compared the structural variation of the catalysts before and after DRM and discussed its correlation with catalytic performance in the “Structural and carbon evolution of spent catalysts” section. The revised text is provided below.\nLine 363-374 on Page 19-20:\nAfter the reaction at 700 °C for 20 h, the metallic Pt diffraction peaks became more apparent, indicating particle growth. HAADF-STEM confirmed that Pt/T-10A still contained a large population of Pt nanoparticles below 2 nm, with only a small fraction of larger crystallites. In contrast, Pt/A exhibited more uniformly grown particles with an average size of 3.54 nm (Supplementary Fig. 12). After the stability test at 800 °C for 100 h, Pt/T-10A showed a slight sharpening of the Pt peaks (Supplementary Fig. 11), and many small particles alongside a few larger ones (Supplementary Fig. 13). The average Pt particle size after long-term test was 2.14 nm, which lies within the size range reported to retain high catalytic activity53,54. These results indicate that the TiO - 2 Al O interface could suppress Pt sintering to some extent under harsh reaction 2 3 conditions and preserve a substantial fraction of finely dispersed, active Pt nanoparticles.\nLine 382-389 on Page 20:\nFurthermore, the XPS results of Pt/T-10A catalysts before and after DRM revealed that no discernible shift in the Pt 4d binding energies could be observed, while the Ti3+/Ti4+ ratio and O /O fraction remained nearly constant (Supplementary Fig. 14). V A These results indicate that the redox state of the TiO -Al O support and the interfacial 2 2 3 electronic environment between Pt and the support were effectively preserved throughout the reaction, despite presence of moderate particle growth, thereby rationalizing the long-term stability of Pt/T-10A under high-temperature DRM conditions.\nLine 242-244 on Page 18 in Supplementary Information:\nSupplementary Figure 14. XPS spectra of spent Pt/T-10A after DRM at 700 °C for 20 h and 800 °C for 100 h in the (a) Pt 4d, (b) Ti 2p, and (c) O 1s regions.\nAccordingly, two new references [53, 54] have been cited:\n53. Hosseini, D., Abdala, P. M., Donat, F., Kim, S. M. & Müller, C. R. Bifunctional core-shell architecture allows stable H production utilizing CH and CO in a catalytic 2 4 2 chemical looping process. Appl. Catal. B Environ. 258, 117946 (2019).\n54. Shen, D. et al. Insight into the dynamic nature of the Pt-CeO interface in dry 2 reforming of methane. Langmuir 40, 13458–13466 (2024).\nComment 7:\nThe authors are suggested to consider the fact, the support material was calcined finally at 400 °C, the catalyst precursors were calcined at 350 °C, and the catalyst samples were reduced at 400 °C before catalytic performance evaluation at 600-800 °C. Are there any structural variation under different temperature conditions?\nResponse:\nWe sincerely thank you for raising this important question. Because the calcination (350 °C) and reduction (400 °C) temperatures are lower than the reaction temperature (600–800 °C), it is reasonable to consider that structural variations may occur under actual reaction conditions. To clarify this, we conducted additional tests on the representative Pt/T-10A catalyst. After reduction at 400 °C, the sample was further heated to 600 °C, 700 °C, and 800 °C for 1 h at each temperature. The results show that Pt nanoparticles undergo only negligible growth under these conditions. In addition, Al O helps stabilize the TiO domains at elevated temperatures1, thereby preserving 2 3 2 the structural integrity of the TiO component during thermal treatment. 2\nMore importantly, characterization of the spent catalyst provides direct evidence of structural stability. After long-term DRM at 800 °C for 100 h, the average Pt particle size increased only to 2.14 nm. Meanwhile, XPS analysis revealed no detectable shift in the Pt 4d binding energy, and both the Ti3+/Ti4+ ratio and the fraction of oxygen species adjacent to oxygen vacancies remained nearly unchanged. These results demonstrate that the redox state of the TiO -Al O support and the interfacial electronic 2 2 3 environment around Pt are well maintained throughout the reaction.\nTaken together, these findings confirm that the catalyst experiences minimal structural variation across different thermal conditions. We have added the corresponding clarification in the revised Supplementary Information.\nReference\n1. Jiang, F. et al. Propane dehydrogenation over Pt/TiO -Al O catalysts. ACS Catal. 2 2 3 5, 438–447 (2015).\nLine 189-200 on Page 13-14 in Supplementary Information:\nSupplementary Figure 6. HAADF-STEM images of reduced Pt/T-10A catalysts. (a) reduced at 400 °C (no further heating); (b) heated to 600 °C; (c) heated to 700 °C; (d) heated to 800 °C and maintained for 1 h.\nTo evaluate potential structural variations of the catalyst under actual DRM conditions, the reduced Pt/T-10A sample (400 °C) was further heated to 600 °C, 700 ° C, and 800 °C and maintained for 1 h at each temperature. HAADF-STEM characterization showed that the average Pt particle size increased only slightly from 1.01 to 1.08, 1.10, and 1.12 nm after the respective heat treatments, indicating negligible sintering even at high temperatures. In addition, Al O is known to stabilize 2 3 TiO domains at elevated temperatures, which contributes to maintaining the structural 2 integrity of the TiO component during thermal treatment11. 2\nAccordingly, a new reference [11] have been cited:\n11. Jiang, F. et al. Propane dehydrogenation over Pt/TiO -Al O catalysts. ACS Catal. 2 2 3 5, 438–447 (2015).\nComment 8:\nThe optimized catalytic performance under optimized conditions were “CH and 4 CO conversions of 91% and 95%, respectively, with an H /CO ratio of 0.97.”, which 2 2 is only quite close to complete conversion of the reactants, limiting the further utilization of the syngas obtained. How could one get higher conversion of the reactants by using the optimized catalyst?\nResponse:\nWe thank you for this insightful comment. To further enhance the reactant conversions, several practical strategies can be considered. These include (i) reducing the gas hourly space velocity (GHSV) or increasing the catalyst bed length to extend the residence time, and (ii) moderately increasing the reaction temperature to drive the strongly endothermic DRM reaction closer to equilibrium conversion. To verify these strategies, we performed additional tests by lowering the space velocity and raising the temperature. Both approaches led to higher CH and CO conversions. Elevating the 4 2 temperature produced a more pronounced improvement owing to the strongly endothermic nature of DRM, and the conversions achieved at 800–900 °C are already close to the thermodynamic equilibrium limit.\nFrom an industrial perspective, however, these adjustments involve important trade-offs. Lowering the space velocity increases the required reactor volume or reduces throughput, while higher operating temperatures raise energy consumption and may shorten the catalyst lifetime. In practical DRM processes, complete conversion is generally not necessary. Instead, the reactor effluent is separated and unreacted CH /CO is recycled to maximize overall reactant utilization. 4 2\nBeyond conversion, the composition of the syngas also plays a crucial role in determining its suitability for downstream processes. In industrial practice, different H /CO ratios are required depending on the targeted application. A ratio close to unity 2 is appropriate for hydrogen production and for Fischer-Tropsch synthesis aimed at long-chain hydrocarbons, where a relatively low H /CO ratio helps suppress excessive 2 hydrogenation. In contrast, methanol synthesis and conventional Fischer-Tropsch operations typically demand a higher H /CO ratio of around 2. 2\nAlthough DRM generates syngas with an H /CO ratio close to 1, this ratio can be 2 readily adjusted when necessary. Such adjustment can be achieved through combined reforming routes in which CH is co-fed with CO , steam, or oxygen, or by applying a 4 2 downstream water-gas shift reaction to obtain the composition required for specific industrial processes1,2.\nReference:\n1. Pakhare, D. & Spivey, J. A review of dry (CO ) reforming of methane over noble 2 metal catalysts. Chem. Soc. Rev. 43, 7813–7837 (2014).\nComment 9:\nProof reading needs to be carefully checked. For example, line 90, “the activation barrier for the 1, a”, the meaning of “1” here is not clear.\nResponse:\nWe sincerely thank you for the careful reading and valuable comments on our manuscript. We acknowledge that the sentence mentioned indeed contained an unclear expression. We have now thoroughly checked the entire manuscript line by line and carefully revised this part to ensure that the expression is accurate and clear.\nLine 108-109 on Page 6:\n“Importantly, DFT results show that the Pt/TiO -Al O catalyst increases the 2 2 3 activation barrier for the CH*→C*, a key step ……”\nReviewer #2:\nComment:\nThe authors have developed an interesting synthesis of titania-coated alumina which is claimed to promote dry reforming reactivity by activating the lattice oxygen in the thin titania layers and improve Pt durability by optimizing Pt charge density.\nThere is a major problem which undercuts the main conclusions of the paper; the authors have turned a blind eye toward crystalline Pt in XRD patterns. This is most evident in Figure S6, in which the Pt(111) and (200) peaks at 39.8 and 46.2 degrees 2theta are mis-identified as alumina. There is indeed a (222) peak of gamma alumina at 39.2 degrees 2theta, but the intensity of this peak is much lower that the peak which appears in the data. Comparison with a pure gamma alumina control sample would have made this clear. Secondly, in Figure S6 both peaks in the range of 45-46 degrees 2theta are attributed to gamma alumina, when gamma alumina does not have two peaks in this region (this can be seen from the gamma alumina PDF reference shown in Figure S1. The second peak is most certainly Pt(200) at 46.2 degrees 2theta. The sharp Pt peaks present in Figure S6 arise from relatively large Pt nanoparticles, and these are actually imaged in the STEM images of Figure S7, but this connection is never made! In like manner, in the Pt/T-20A diffractogram in Figure S1, the Pt(111) peak is again clearly seen, and the Pt(200) peak can be seen as a right hand shoulder on the 45 degree 2theta peak. Once again in Figure 5a for the 20 h reacted catalysts, crystalline (111) and (200) Pt peaks prominently appear for 10A, 20A, and A catalysts but are not identified as such. In fact, there is clearly crystalline Pt seen in Figure 1a in the P/T-20A sample, and perhaps also the P/T-10A sample.\nThe extensive sintering of the P/T-10A sample calls into question the claims for enhanced stability, as well as the suitability of 5-atom Pt clusters to represent the Pt phase in the simulations. The faulty interpretation of XRD data must be corrected. The conclusions must be reimagined and brought into alignment with accurate characterization. Obtaining diffractograms of pure gamma alumina as an XRD control sample will help interpret the results.\nResponse 1:\nWe sincerely thank you for this insightful comment and for pointing out our critical misinterpretation of the XRD patterns. Indeed, the diffraction peaks of crystalline Pt nanoparticles were mistakenly assigned to the γ-Al O support. We have supplemented 2 3 the XRD pattern of pure γ-Al O and corrected the corresponding discussion. We have 2 3 also refined the description related to Pt particle growth to more accurately reflect the extent of sintering observed in the spent Pt/T-10A catalyst. The conclusions in the “Structure of catalysts” and “Structural and carbon evolution of spent catalysts” sections, as well as in Supplementary Information, have been updated to ensure consistency and to better correlate the XRD results with the post-reaction HAADF-STEM observations.\nLine 116-129 on Page 6-7:\nStructures of as-prepared Pt/A, Pt/T, and Pt/T-xA catalysts were well characterized. The XRD patterns of reduced Pt/A, Pt/T, and Pt/T-xA catalysts were depicted in Supplementary Fig. 1. ……When the Ti/Al ratio is 1:10, no characteristic diffraction peaks of TiO were observed, indicating that TiO is present in a highly dispersed state 2 2 on the surface of Al O support.32 For the reduced Pt/A and Pt/T-xA catalysts, the 2 3 characteristic diffraction peaks of metallic Pt at around 39.8° (Pt(111)) and 46.2° (Pt(200)) coincide with the main diffraction peaks of γ-Al O . In the surface-sensitive 2 3 GIXRD patterns (Supplementary Fig. 2), these Pt-related features appear as weak shoulder signals, indicating the presence of small, highly dispersed Pt nanoparticles.\nLine 168-169 on Page 9 in Supplementary Information:\nSupplementary Figure 1. XRD patterns of reduced Pt/T, Pt/T-xA, and Pt/A catalysts.\nLine 171-173 on Page 9-10 in Supplementary Information:\nSupplementary Figure 2. GIXRD patterns of reduced Pt/T-3A, Pt/T-10A, and Pt/T- 20A catalysts.\nLine 363-374 on Page 19-20:\nAfter the reaction at 700 °C for 20 h, the metallic Pt diffraction peaks became more apparent, indicating particle growth. HAADF-STEM confirmed that Pt/T-10A still contained a large population of Pt nanoparticles below 2 nm, with only a small fraction of larger crystallites. In contrast, Pt/A displayed more uniformly grown particles with an average size of 3.54 nm (Supplementary Fig. 12). After the stability test at 800 °C for 100 h, Pt/T-10A showed a slight sharpening of the Pt peaks (Supplementary Fig. 11), and many small particles alongside a few larger ones (Supplementary Fig. 13). The average Pt particle size after long-term test was 2.14 nm, which lies within the size range reported to retain high catalytic activity53,54. These results indicate that the TiO - 2 Al O interface could suppress Pt sintering to some extent under harsh reaction 2 3 conditions and preserve a substantial fraction of finely dispersed, active Pt nanoparticles.\nLine 408-410 on Page 21-22:\nFig. 5 a XRD patterns of spent catalysts after 20 h of DRM.\nLine 231-233 on Page 16 in Supplementary Information:\nSupplementary Figure 11. XRD patterns of the spent Pt/T-10A catalyst after 100 h of DRM at 800 °C.\nAccordingly, two new references [53, 54] have been cited:\n53. Hosseini, D., Abdala, P. M., Donat, F., Kim, S. M. & Müller, C. R. Bifunctional core-shell architecture allows stable H production utilizing CH and CO in a catalytic 2 4 2 chemical looping process. Appl. Catal. B Environ. 258, 117946 (2019).\n54. Shen, D. et al. Insight into the dynamic nature of the Pt-CeO interface in dry 2 reforming of methane. Langmuir 40, 13458–13466 (2024).\nResponse 2:\nWe have now provided a clear justification for the use of a Pt cluster to represent 5 Pt nanoparticles in Supplementary Information.\nLine 115-124 on Page 6-7 in Supplementary Information:\nA Pt cluster was adopted as a representative model to describe the local active 5 ensemble of Pt nanoparticles in the DFT calculations. The catalytic activity of supported Pt catalysts mainly originates from low coordination atoms located at particle edges and at the metal oxide interface, rather than from the extended terraces of large particles. Comparative studies of Pt , Pt , Pt , and Pt clusters on TiO have shown 5 8 13 19 2 that the key electronic descriptors and charge transfer characteristics become essentially converged when only a few atomic layers are included. This demonstrates that small clusters can reliably capture the interfacial chemistry of realistic Pt nanoparticles8. In addition, similar few atom cluster models such as Pt and Pt have been successfully 3 4 applied to oxide supported Pt catalysts9,10.\nAccordingly, three new references [8-10] have been cited:\n8. Wang, D., Liu, Z.-P. & Yang, W.-M. Revealing the size effect of platinum cocatalyst for photocatalytic hydrogen evolution on TiO support: a DFT study. ACS 2 Catal. 8, 7270–7278 (2018).\n9. Chen, X. et al. Regulating coordination number in atomically dispersed Pt species on defect-rich graphene for n-butane dehydrogenation reaction. Nat. Commun. 12, 2664 (2021).\n10. Sun, K., Shen, C., Zou, R. & Liu, C. Highly active Pt/In O -ZrO catalyst for CO 2 3 2 2 hydrogenation to methanol with enhanced CO tolerance: The effects of ZrO . Appl. 2 Catal. B Environ. 320, 122018 (2023).\nReviewer #3:\nI. Introduction\nComment 1:\nP39, the authors should explain why DRM has higher energy efficiency compared to SMR and POX.\nResponse:\nWe sincerely thank you for this insightful comment. As suggested, we have expanded the Introduction section to include a concise comparison of the energetic and environmental characteristics of DRM, SRM, and POX. The modified paragraph reads as follows.\nLine 36-48 on Page 2-3:\nCompared with conventional methane reforming routes, DRM offers distinct environmental and process advantages. Steam reforming of methane (SRM, CH + H O 4 2 → CO + 3H , ΔH = +206 kJ·mol-1) is a mature process that produces syngas at the 2 298K industrial scale, but it requires a continuous supply of high-temperature steam and substantial external heat input. Partial oxidation of methane (POX, CH + 0.5O → CO 4 2 + 2H , ΔH = –36 kJ·mol⁻¹) can be thermally self-sustained. However, the intense 2 298K local heat release can create hot spots leading to safety concerns, and it may still suffer from carbon deposition3. In contrast, DRM (CH + CO → 2CO + 2H , ΔH = +247 4 2 2 298K kJ·mol⁻¹) directly utilizes CO together with CH to generate syngas without addition 2 4 of steam or oxygen. Its high-temperature operation also enables effective integration with renewable heat or industrial waste-heat sources. As a result, DRM offers higher carbon utilization efficiency and potential process-level energy benefits, making it an attractive route for sustainable energy conversion4.\nAccordingly, two new references [3, 4] have been cited:\n3. Wang, Z. et al. Insight into the activity of Ni-based thermal catalysts for dry reforming of methane. J. Mater. Chem. A 12, 24802–24838 (2024).\n4. Mondal, U. & Yadav, G. D. Methanol economy and net zero emissions: critical analysis of catalytic processes, reactors and technologies. Green Chem. 23, 8361–8405 (2021).\nComment 2:\nP47, an important fraction of the deposited carbon is generated on highly active Ni(110) sites; therefore, alloying Ni with other metals could help reduce deactivation. Such a strategy should be mentioned.\nResponse:\nWe sincerely thank you for the thoughtful suggestion. We fully agree the reviewer. As suggested, we have added a brief discussion in the Introduction section, summarizing the recent advances of Ni-based catalysts and clarifying the reason for employing Pt-based catalysts in this work. The revised paragraph now reads as follows.\nLine 55-63 on Page 3-4:\nNi-based catalysts are widely studied due to their high CH activation ability and 4 low cost. To improve their long-term stability in DRM, strategies such as introducing promoters, alloying Ni with other metals, and constructing confinement structures have been explored9-12. However, the inherent tendency of Ni to promote carbon formation and to undergo sintering under DRM conditions remains a major limitation for achieving long-term durability. In contrast, noble metals such as Pt generally exhibit a much higher intrinsic resistance to carbon deposition, which allows for a clearer investigation of coke suppression and interfacial reaction mechanisms under harsh reforming conditions1.\nAccordingly, four new references [9-12] have been cited:\n9. Cheng, F., Duan, X. & Xie, K. Dry reforming of CH /CO by stable Ni nanocrystals 4 2 on porous single-crystalline MgO monoliths at reduced temperature. Angew. Chem. Int. Ed. 60, 18792–18799 (2021).\n10. Johnson, O. et al. Stabilizing catalytic performance in dry reforming of methane via surface-engineered intermetallic carbide nanoparticles. J. Am. Chem. Soc. 147, 16786–16791 (2025).\n11. Wang, Q. et al. Interface engineering of oxygen-vacancy-rich MgO/Ni@NiAlO enables low-temperature coke-free methane dry reforming. Chin. J. Catal. 75, 9–20 (2025).\n12. He, D. et al. Designing ultra-stable and surface-exposed Ni nanoparticles with dually confined microenvironment for high-temperature methane dry reforming. Adv. Funct. Mater. 35, 2412895 (2025).\nComment 3:\nP57, indeed, CH* → C* is an essential pathway for coke formation. However, this route also exists in SMR, where coke deposition is well controlled by providing sufficient oxidant from steam. Therefore, the dissociation of CO to O* plays a key role 2 in burning coke. I suggest that these pathways be studied at least at the DFT level.\nResponse:\nWe sincerely thank you for this insightful comment. The discussion on CO 2 dissociation and the subsequent role of oxygen species in coke oxidation has been incorporated into both the Introduction and DFT calculations of the revised manuscript.\nLine 76-78 on Page 4:\nTherefore, the rational design of catalysts should aim to precisely control CH 4 decomposition pathways while enabling CO -derived oxygen species to actively 2 participate in carbon oxidation.\nLine 571-590 on Page 29-30:\nTo further clarify the role of oxygen species generated from CO dissociation in 2 carbon oxidation, we calculated the energy barriers for CO dissociation and the 2 subsequent C–O coupling reactions on Pt /TiO (001)-Al O (100) and Pt /Al O (100) 5 2 2 3 5 2 3 models (Supplementary Fig. 23).\nIn the Pt /TiO (001)-Al O (100) model, the O atom released from CO dissociation 5 2 2 3 2 at an interfacial Pt site preferentially fills an oxygen vacancy on the TiO surface, 2 forming lattice oxygen. A lattice oxygen atom located near the interface can then react with a neighboring C* to produce CO, while simultaneously regenerating the oxygen vacancy, thereby establishing a dynamic cycle between oxygen vacancies and lattice oxygen, which resembles a Mars-van Krevelen-type oxidation mechanism77. In contrast, in the Pt /Al O (100) model, the O atom produced from CO dissociation directly 5 2 3 2 oxidizes the surface C* to form CO.\nThe calculated activation barriers for CO dissociation and the subsequent 2 oxidation step on Pt /TiO (001)-Al O (100) are 0.66 eV and 0.97 eV, respectively, 5 2 2 3 which are significantly lower than those on Pt /Al O (100) (0.88 eV and 1.91 eV). 5 2 3 Combined with the in situ DRIFTS results, these findings suggest that the dynamic cycle between oxygen vacancies and lattice oxygen enables continuous regeneration of active oxygen species during the reaction, thereby promoting the oxidation of carbon deposits. This beneficial behavior is attributed to the ultra-thin anatase TiO overlayer, 2 which provides accessible vacancies together with mobile lattice oxygen.\nAccordingly, a new reference [77] have been cited:\n77. Tang, Y. et al. Synergy of single-atom Ni and Ru sites on CeO for dry reforming 1 1 2 of CH . J. Am. Chem. Soc. 141, 7283–7293 (2019).\nSupplementary Figure 23. Energy diagram for CO decomposition and subsequent 2 C–O coupling on Pt /TiO (001)-Al O (100) and Pt /Al O (100) catalysts. Coloring 5 2 2 3 5 2 3 scheme: dark blue (Pt), pink (O), blue (Ti), green (Al), and brown (C).\nComment 4:\nP69, Since TiO is a reducible metal oxide, the authors should provide stronger 2 justification for its selection, particularly given that CeO can also undergo partial 2 reduction.\nResponse:\nWe sincerely thank you for the valuable comment. The rationale for selecting TiO 2 has been further clarified in the revised Introduction.\nLine 87-94 on Page 5:\nTiO , as a classical support for studying strong metal-support interactions (SMSI), 2 readily generates oxygen vacancies under reducing conditions, which play a crucial role in CO activation and the oxidation of surface carbon species during DRM22,23. 2 Compared with other reducible oxides such as CeO and ZrO , TiO offers a more cost- 2 2 2 effective, tunable, and moderately reducible platform that enables controlled SMSI with Pt. This tunability enables controlled electron transfer at the metal-support interface, optimizing the Pt electronic state to balance CH activation and coke resistance24,25. 4\nAccordingly, four new references [22-25] have been cited:\n22. Tauster, S. J., Fung, S. C. & Garten, R. L. Strong metal-support interactions. Group 8 noble metals supported on titanium dioxide. J. Am. Chem. Soc. 100, 170–175 (1978).\n23. Chen, S. et al. Defective TiO overlayers catalyze propane dehydrogenation x promoted by base metals. Science 385, 295–300 (2024).\n24. Lu, Z. et al. Modulation of metal-support interactions in Pt-TiO synergistic x catalysts for propane dehydrogenation. Chem. Eng. Sci. 297, 120304 (2024).\n25. Jiang, F. et al. Propane dehydrogenation over Pt/TiO -Al O catalysts. ACS Catal. 2 2 3 5, 438–447 (2015).\nII. Materials and Methods\nComment:\nP107, the authors should clarify why a loading of 3 wt% Pt was selected, given that typical Pt loadings are below 1 wt%. This value seems unusually high for such a precious metal. In addition, the rationale for choosing Pt over Ni should be explained.\nResponse 1:\nWe thank you for this thoughtful comment. In our study, we systematically evaluated the influence of different Pt loadings (0.5–5 wt%) on the catalytic performance in the DRM reaction. The corresponding results are provided in Supplementary Information (Supplementary Fig. 24). The Pt/T-10A catalyst containing 3 wt% Pt was chosen with consideration of both catalytic performance and precious-metal utilization. It exhibited higher CH and CO conversions together with an 4 2 appropriate H₂/CO ratio, and was therefore selected as the optimal loading for further investigation. In our future work, we aim to further explore strategies to achieve comparable activity and stability at lower Pt loadings.\nSeveral previous studies reported that metal loadings in noble metal catalysts for DRM is commonly in the range of 2–4 wt%, particularly when noble metals serve as the primary active component. For instance, Zhou et al. (Ru 2 wt%) demonstrated excellent structural stability of Ru/LaO -SiO under high-temperature conditions1. Ye x 2 et al. (Rh 3 wt%) achieved highly dispersed and exposed Rh nanoparticles exsolved from a Ce–Sm oxide matrix2. Naeem et al. (Ru 3 wt%) synthesized Sm 2 RuxCe 2-x O 7 catalysts exhibiting superior activity and long-term stability3, and Jiménez et al. (Pd 4 wt%) developed Pd–CeO 2 catalysts with enhanced DRM performance4. Additionally, Armengol-Profitós et al. reported CoRu/CeO catalysts (Ru 1.5 wt%, Co 10 wt%) in 2 which a relatively high overall metal content contributed to improved activity and stability5.\nReference:\n1. Zhou, T. et al. Ultrafine metal nanoparticles isolated on oxide nano-islands as exceptional sintering-resistant catalysts. Nat. Mater. 24, 891–899 (2025).\n2. Ye, Y. et al. Harmonizing nanoparticle exsolution from Ce–Sm oxide matrix for stable methane dry reforming. Angew. Chem. Int. Ed. 64, e202503997 (2025).\n3. Naeem, M. A. et al. Exsolution of metallic Ru nanoparticles from defective, fluorite-type solid solutions Sm RuxCe O to impart stability on dry reforming 2 2–x 7 catalysts. ACS Catal. 10, 1923–1937 (2020).\n4. Jiménez, J. D. et al. Identification of highly selective surface pathways for methane dry reforming using mechanochemical synthesis of Pd-CeO . ACS Catal. 12, 12809– 2 12822 (2022).\n5. Armengol-Profitós, M. et al. Enhancing the performance of a novel CoRu/CeO 2 bimetallic catalyst for the dry reforming of methane via a mechanochemical process. Appl. Catal. B Environ. Energy 345, 123624 (2024).\nLine 626 on Page 33:\nAll catalysts had a platinum loading of 3 wt% (Supplementary Fig. 24).\nLine 288-295 on Page 23 in Supplementary Information:\nSupplementary Figure 24. DRM performance of Pt/T-10A catalysts under different Pt loading. Reaction conditions: 700 °C, CH : CO : N = 1:1:1, GHSV = 54000 mL·h- 4 2 2 1·g -1. cat\nThe catalytic performance of Pt/T-10A catalysts with different Pt loadings (0.5–5 wt%) in the DRM reaction was evaluated. The catalyst containing 3 wt% Pt exhibited higher CH and CO conversions together with an appropriate H /CO ratio, and was 4 2 2 therefore selected as the optimal loading for subsequent experiments.\nResponse 2:\nWe thank you for this considerate comment. We have now added a discussion in the Introduction section to address the recent progress of Ni-based catalysts and to clarify the rationale for employing Pt-based catalysts in this work. The revised text reads as follows.\nLine 55-63 on Page 3-4:\nNi-based catalysts are widely studied due to their high CH activation ability and 4 low cost. To improve their long-term stability in DRM, strategies such as introducing promoters, alloying Ni with other metals, and constructing confinement structures have been explored9-12. However, the inherent tendency of Ni to promote carbon formation and to undergo sintering under DRM conditions remains a major limitation for achieving long-term durability. In contrast, noble metals such as Pt generally exhibit a much higher intrinsic resistance to carbon deposition, which allows for a clearer investigation of coke suppression and interfacial reaction mechanisms under harsh reforming conditions1.\nAccordingly, four new references [9-12] have been cited:\n9. Cheng, F., Duan, X. & Xie, K. Dry reforming of CH /CO by stable Ni nanocrystals 4 2 on porous single-crystalline MgO monoliths at reduced temperature. Angew. Chem. Int. Ed. 60, 18792–18799 (2021).\n10. Johnson, O. et al. Stabilizing catalytic performance in dry reforming of methane via surface-engineered intermetallic carbide nanoparticles. J. Am. Chem. Soc. 147, 16786–16791 (2025).\n11. Wang, Q. et al. Interface engineering of oxygen-vacancy-rich MgO/Ni@NiAlO enables low-temperature coke-free methane dry reforming. Chin. J. Catal. 75, 9–20 (2025).\n12. He, D. et al. Designing ultra-stable and surface-exposed Ni nanoparticles with dually confined microenvironment for high-temperature methane dry reforming. Adv. Funct. Mater. 35, 2412895 (2025).\nIII. Results and Discussion\nComment 1:\nP160, Figure 1. The XRD patterns and N adsorption–desorption isotherms should 2 be presented separately and in an expanded form.\nResponse:\nWe thank you for this valuable suggestion. The XRD patterns and N₂ adsorption– desorption isotherms have now been presented separately and in an expanded form to improve clarity. These revised figures are provided in Supplementary Information.\nLine 168-169 on Page 9 in Supplementary Information:\nSupplementary Figure 1. XRD patterns of reduced Pt/T, Pt/T-xA, and Pt/A catalysts.\nLine 202-204 on Page 14 in Supplementary Information:\nSupplementary Figure 7. N adsorption-desorption isotherms and pore size 2 distribution curves of the reduced catalysts.\nComment 2:\nP321/322, please provide references regarding the deactivation rates of the mentioned catalysts.\nResponse:\nWe thank you for the valuable suggestion. In accordance with the comment, we have added appropriate literature references to support the statements regarding catalyst deactivation rates in the “Catalyst performance evaluations” section. The revised text with the corresponding citations is now included as follows.\nLine 324-325 on Page 17:\n“Additionally, Pt/T-10A catalyst exhibited a low deactivation rate constant (k = d 4.25 × 10⁻3 h-1)47,48,”\nAccordingly, two new references [47, 48] have been cited:\n47. Liu, K. et al. Development of a highly stable ternary alloy catalyst for dry reforming of methane. ACS Catal. 13, 3541–3548 (2023).\n48. Xu, M., Zhang, B., Zhang, R., Xia, L. & Liu, G. Zinc migration mediates isolated [PtFe ] in zeolite for propane dehydrogenation. ACS Catal. 15, 3215–3226 (2025). 3\nComment 3:\nP369 and Table S5(SI), The authors reported weight loss but did not specify how it was calculated. It is highly recommended to present the corresponding TGA curves.\nResponse:\nWe thank you for this helpful comment. The corresponding TGA curves used for this calculation are provided in the “Structural and carbon evolution of spent catalysts” section of the main text (Fig. 5b), and the numerical results are summarized in Supplementary Table 5. The formula used to calculate the weight loss has now been added in Supplementary Information.\nLine 408-410 on Page 21-22:\nFig. 5 (b) TG curves of spent catalysts after 20 h of DRM.\nLine 329-334 on Page 27-28 in Supplementary Information:\nSupplementary Table 5. Weight loss during the TGA analysis, deposited carbon amount, and I /I ratios calculated for spent catalysts. D G\nDeposited carbon Catalyst Weight loss (%)a I /I b D G (mg g -1)a cat\nPt/T 0.33 2.9 1.09\nPt/T-3A 2.82 25.3 1.13\nPt/T-10A 3.53 32.2 1.53\nPt/T-20A 4.50 41.6 1.20\nPt/A 5.90 54.8 0.56\na Weight loss (ΔWL) was calculated by eq. S5. b Measured by Raman spectra.\nΔWL(%)= mi-m f×100 (5) mi\nwhere m, and m are the initial mass, and final mass of spent catalysts. i f\nComment 4:\nP475, the authors should justify their choice of a Pt cluster to represent Pt 5 nanoparticles.\nResponse:\nWe sincerely thank you for this valuable suggestion. We have now provided a clear justification for the use of a Pt cluster to represent Pt nanoparticles in Supplementary 5 Information.\nLine 115-124 on Page 6-7 in Supplementary Information:\nA Pt cluster was adopted as a representative model to describe the local active 5 ensemble of Pt nanoparticles in the DFT calculations. The catalytic activity of supported Pt catalysts mainly originates from low coordination atoms located at particle edges and at the metal oxide interface, rather than from the extended terraces of large particles. Comparative studies of Pt , Pt , Pt , and Pt clusters on TiO have shown 5 8 13 19 2 that the key electronic descriptors and charge transfer characteristics become essentially converged when only a few atomic layers are included. This demonstrates that small clusters can reliably capture the interfacial chemistry of realistic Pt nanoparticles8. In addition, similar few atom cluster models such as Pt and Pt have been successfully 3 4 applied to oxide supported Pt catalysts9,10.\nReference:\n8. Wang, D., Liu, Z.-P. & Yang, W.-M. Revealing the size effect of platinum cocatalyst for photocatalytic hydrogen evolution on TiO support: a DFT study. ACS 2 Catal. 8, 7270–7278 (2018).\n9. Chen, X. et al. Regulating coordination number in atomically dispersed Pt species on defect-rich graphene for n-butane dehydrogenation reaction. Nat. Commun. 12, 2664 (2021).\n10. Sun, K., Shen, C., Zou, R. & Liu, C. Highly active Pt/In O -ZrO catalyst for CO 2 3 2 2 hydrogenation to methanol with enhanced CO tolerance: The effects of ZrO . Appl. 2 Catal. B Environ. 320, 122018 (2023).\nComment 5:\nThe authors should address the oxidation pathway associated with O species generated from CO dissociation. 2\nResponse:\nWe greatly appreciate your valuable suggestion. In response, we have added a detailed discussion in DFT calculations of the revised manuscript.\nLine 571-590 on Page 29-30:\nTo further clarify the role of oxygen species generated from CO dissociation in 2 carbon oxidation, we calculated the energy barriers for CO dissociation and the 2 subsequent C–O coupling reactions on Pt /TiO (001)-Al O (100) and Pt /Al O (100) 5 2 2 3 5 2 3 models (Supplementary Fig. 23).\nIn the Pt /TiO (001)-Al O (100) model, the O atom released from CO dissociation 5 2 2 3 2 at an interfacial Pt site preferentially fills an oxygen vacancy on the TiO surface, 2 forming lattice oxygen. A lattice oxygen atom located near the interface can then react with a neighboring C* to produce CO, while simultaneously regenerating the oxygen vacancy, thereby establishing a dynamic cycle between oxygen vacancies and lattice oxygen, which resembles a Mars-van Krevelen-type oxidation mechanism77. In contrast, in the Pt /Al O (100) model, the O atom produced from CO dissociation directly 5 2 3 2 oxidizes the surface C* to form CO.\nThe calculated activation barriers for CO dissociation and the subsequent 2 oxidation step on Pt /TiO (001)-Al O (100) are 0.66 eV and 0.97 eV, respectively, 5 2 2 3 which are significantly lower than those on Pt /Al O (100) (0.88 eV and 1.91 eV). 5 2 3 Combined with the in situ DRIFTS results, these findings suggest that the dynamic cycle between oxygen vacancies and lattice oxygen enables continuous regeneration of active oxygen species during the reaction, thereby promoting the oxidation of carbon deposits. This beneficial behavior is attributed to the ultra-thin anatase TiO overlayer, 2 which provides accessible vacancies together with mobile lattice oxygen.\nAccordingly, a new reference [77] have been cited:\n77. Tang, Y. et al. Synergy of single-atom Ni and Ru sites on CeO for dry reforming 1 1 2 of CH . J. Am. Chem. Soc. 141, 7283–7293 (2019).\nSupplementary Fig. 23. Energy diagram for CO decomposition and subsequent C–O 2 coupling on Pt /TiO (001)-Al O (100) and Pt /Al O (100) catalysts. Coloring scheme: 5 2 2 3 5 2 3 dark blue (Pt), pink (O), blue (Ti), green (Al), and brown (C).\nComment 6:\nThe acidity of the supports can catalyse the successive dehydrogenation of methane. The authors are requested to clarify why this important parameter was neglected in their discussion.\nResponse:\nWe sincerely appreciate your insightful comment regarding the role of support acidity in the DRM reaction. In response, we have performed NH -TPD measurements 3 on Pt/T-10A and Pt/A, and supplemented the results and corresponding discussion in the revised manuscript. Both catalysts exhibited three types of NH desorption features, 3 corresponding to physically adsorbed NH , medium, and strong acid sites. Pt/T-10A 3 showed more pronounced medium and strong acidity due to the presence of Ti4+ Lewis acid sites and the possible formation of Ti–O–Al linkages. Although increased acidity is often assumed to enhance CH cracking and thereby favor coke formation, the Pt/T- 4 10A catalyst nevertheless displays higher stability and lower carbon deposition under DRM conditions. This behavior is attributed to the electronic nature of Ti4+, whose stable d0 configuration limits its ability to accept electrons from CH intermediates and x therefore makes these acid sites less effective in driving deep dehydrogenation. By contrast, Al3+ sites possess lower-energy vacant orbitals that facilitate electron withdrawal from CH species, increasing the tendency for coke formation on Pt/A. x\nHence, the observed stability trend cannot be explained by acidity alone.\nIn combination with DFT calculations and spectroscopic analyses, we conclude that the high stability of the Pt/T-10A catalyst originates from the cooperative modulation of CH activation and lattice-oxygen-driven carbon removal at the TiO – 4 2 Al O interface. The interfacial Ti–O–Al structure induces lattice contraction and 2 3 charge redistribution, optimizing the electronic environment of Pt clusters. Consequently, the Pt sites at this interface possess a moderated electron density and a suitably downshifted d-band center, which weakens excessive CH adsorption and 4 increases the barrier for deep CH* → C* dehydrogenation, thereby effectively suppressing coke formation. DFT results further show that the TiO –Al O interface 2 2 3 enhances CO dissociation and enables a low energy cycle between oxygen vacancies 2 and lattice oxygen, which accelerates C–O coupling and allows lattice oxygen to participate efficiently in carbon oxidation.\nFor completeness, we have added the NH -TPD data and corresponding discussion 3 in the Surface and Interface Properties and Supplementary Information to clarify this point.\nLine 236-239 on Page 12:\nThe surface acid properties of Pt/T-10A and Pt/A were further characterized by NH -TPD (Supplementary Fig. 9), revealing the influence of Ti incorporation on the 3 surface acidity. The detailed explanation is provided in Supplementary Information.\nLine 58-67 on Page 4 in Supplementary Information:\nNH temperature programmed desorption (NH -TPD) measurements were 3 3 conducted on the Micromeritics AutoChem II 2920 instrument. Prior to the measurement, the catalysts (100 mg) were pretreated under an inert gas flow while heating to 300 °C at a rate of 10 °C·min⁻¹ and maintained for 1 h. The samples were then reduced in a 10% H /Ar flow (40 mL·min⁻¹) at 400 °C for 1 h. After reduction, the 2 system was purged with He and cooled to 50 °C. Subsequently, the catalysts were exposed to a 10% NH /He flow (40 mL·min⁻¹) for 1 h to allow adsorption, followed by 3 purging with He (40 mL·min⁻¹) for 1 h to remove weakly physisorbed NH . Finally, 3 the catalysts were heated to 800 °C at a rate of 10 °C·min⁻¹ under He flow, and the desorbed NH was detected using a thermal conductivity detector (TCD). 3\nLine 209-224 on Page 15-16 in Supplementary Information:\nSupplementary Figure 9. NH -TPD profiles of reduced Pt/T-10A and Pt/A catalysts. 3\nNH -TPD profiles of Pt/T-10A and Pt/A catalysts are shown in Supplementary Fig. 3 9. Both catalysts exhibited three desorption regions corresponding to physically adsorbed NH , medium, and strong acid sites. while Pt/T-10A catalyst displayed more 3 pronounced medium and strong acidity, which can be attributed to the presence of Ti4+ Lewis acid sites and the possible formation of Ti–O–Al linkages11,12. Generally, increased surface acidity is considered to facilitate CH cracking and thereby increase 4 the tendency for coke formation13. However, despite the stronger acidity, the Pt/T-10A catalyst displays much higher stability under DRM conditions. This behavior arises from the electronic characteristics of Ti4+, whose stable d0 configuration provides limited capacity to accept electrons. As a result, Ti4+ sites interact weakly with CH x intermediates in electron-transfer steps and are less inclined to drive deep dehydrogenation. In contrast, Al3+ sites possess lower-energy vacant orbitals that can more readily accept electrons, thereby facilitating CH dehydrogenation and increasing x the tendency for coke formation.\nAccordingly, three new references [11-13] have been cited:\n11. Jiang, F. et al. Propane dehydrogenation over Pt/TiO -Al O catalysts. ACS Catal. 2 2 3 5, 438–447 (2015).\n12. Baamran, K., Lawson, S., Rownaghi, A. A. & Rezaei, F. Reactive capture and conversion of CO into hydrogen over bifunctional structured Ce Co NiO /Ca 2 1–x x 3 perovskite-type oxide monoliths. JACS Au 4, 101–115 (2024).\n13. Ni, J., Chen, L., Lin, J. & Kawi, S. Carbon deposition on borated alumina supported nano-sized Ni catalysts for dry reforming of CH . Nano Energy 1, 674–686 (2012). 4"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have addressed my comments carefully. I have no other comment and recommend acceptance of it for publication.", "reviewer_2": "Two main comments:\n1) The main criticism offered in the initial review was the inadequate characterization of the Pt crystalline phase in the XRD patterns. This is only partially rectified in the revision. Mention of crystalline Pt is indeed made where it appears in the XRD figures, but the XRD characterization has not been quantified nor tied into the STEM characterization. This inadequacy is clearest in the authors’ statement in lines 367 and following that\n“Pt/T-10A showed a slight sharpening of the Pt peaks (Supplementary Fig. 11), and many small particles alongside a few larger ones (Supplementary Fig. 13). The average Pt particle size after long-term test was 2.14 nm”…\n- In fact, Supplementary Figure 11 does not show a “slight sharpening” of the Pt peaks, but rather, the abrupt appearance of large Pt particles. A quick estimate from the FWHM of about 1.5 degrees 2 theta, and employing the Scherrer equation, gives an XRD size of 11 nm. This represents a dramatic change in the dispersion of the Pt phase compared to the fresh catalyst.\n- It appears that the authors deemphasize this XRD result in lieu of the STEM results which give an average size of 2.14 nm. Note that Supplementary Figure 13 reveals particles in the range of 10 -20 nm. The authors have failed to take these large particles into consideration, which should be done by reporting the STEM volume average, which can be calculated from the data they have used to compute and report the number average. It is the volume average which must be compared with XRD size estimates (and a surface average which must be compared with chemisorption size estimates). The volume average, for a highly polydisperse sample like the one in question, will be much higher than the number average. Even a small fraction of large particles, as seen in Sup. Fig. 13, will greatly boost the volume average size. My guess is that the STEM volume average would agree rather well with the XRD estimate from the Scherrer equation.\n- The argument the authors are making is that there still exists a high fraction of particles close to 2 nm, which is the most active size range. It is the active area of the nanoparticles which impart the reactivity, and to adequately make this argument, the area STEM averages should be discussed. What fraction of the total surface area of supported nanoparticles exists on optimally sized particles? Further analysis should (and likely will) demonstrate this to be the case.\n2) There is inadequate detail on the Pt deposition procedure. What Pt precursor was used (chloroplatinic acid)? What was its purity? “Impregnation” is too vague; if it was incipient wetness impregnation, what pore volume of solution was used per mass of support? How was the contacted slurry dried and pre-treated (times, temperatures, ramp rate, flow rates and composition of gases)? Without this detail it would be very difficult for another lab to replicate the synthesis.", "reviewer_3": "After reviewing the modifications incorporated in the first revision, I have observed a distinct improvement in the paper's quality. The authors have diligently taken into account the suggestions provided by both my colleagues and me during the previous review."}, "author_response": "Point-by-point responses to reviewers’ comments on “Modulation of Pt Electron Transfer via Engineered Ultra-Thin TiO -Al O Interfaces for Coke-Resistant Methane Dry 2 2 3 Reforming” (NCOMMS-25-66180A)\nReviewer #1:\nThe authors have addressed my comments carefully. I have no other comment and recommend acceptance of it for publication.\nReviewer #2:\nComment 1:\nThe main criticism offered in the initial review was the inadequate characterization of the Pt crystalline phase in the XRD patterns. This is only partially rectified in the revision. Mention of crystalline Pt is indeed made where it appears in the XRD figures, but the XRD characterization has not been quantified nor tied into the STEM characterization. This inadequacy is clearest in the authors’ statement in lines 367 and following that “Pt/T-10A showed a slight sharpening of the Pt peaks (Supplementary Fig. 11), and many small particles alongside a few larger ones (Supplementary Fig. 13). The average Pt particle size after long-term test was 2.14 nm”…\nIn fact, Supplementary Figure 11 does not show a “slight sharpening” of the Pt peaks, but rather, the abrupt appearance of large Pt particles. A quick estimate from the FWHM of about 1.5 degrees 2 theta, and employing the Scherrer equation, gives an XRD size of 11 nm. This represents a dramatic change in the dispersion of the Pt phase compared to the fresh catalyst.\nIt appears that the authors deemphasize this XRD result in lieu of the STEM results which give an average size of 2.14 nm. Note that Supplementary Figure 13 reveals particles in the range of 10 -20 nm. The authors have failed to take these large particles into consideration, which should be done by reporting the STEM volume average, which can be calculated from the data they have used to compute and report the number average. It is the volume average which must be compared with XRD size estimates (and a surface average which must be compared with chemisorption size estimates). The volume average, for a highly polydisperse sample like the one in question, will be much higher than the number average. Even a small fraction of large particles, as seen in Sup. Fig. 13, will greatly boost the volume average size. My guess is that the STEM volume average would agree rather well with the XRD estimate from the Scherrer equation.\nThe argument the authors are making is that there still exists a high fraction of particles close to 2 nm, which is the most active size range. It is the active area of the nanoparticles which impart the reactivity, and to adequately make this argument, the area STEM averages should be discussed. What fraction of the total surface area of supported nanoparticles exists on optimally sized particles? Further analysis should (and likely will) demonstrate this to be the case.\nResponse 1:\nWe thank you for your careful and insightful comment. We agree that the number- average particle diameter obtained using scanning transmission electron microscopy (STEM) did not agree well with the particle size calculated using the Scherrer equation. Accordingly, in the revised manuscript, we added a quantitative correlation by comparing the XRD Scherrer-estimated Pt crystallite size with the STEM volume- average diameter (D[4,3]). As shown in Table R1, the volume-average diameter (7.21 nm) is closer to crystllite diameter (10.34 nm) than the number-average diameter (2.14 nm). It is speculated that the differences in the particle size values between HAADF-STEM and XRD arise from the distinct physical weighting inherent to each technique. Because crystallite sizes extracted from diffraction line-broadening analysis are volume-weighted quantities, the XRD-derived “average size” may be biased toward the larger crystallites in a polydisperse sample due to a reduction of the effective peak broadening (FWHM).1\nIn addition, Pt is expected to exhibit diffraction reflections at approximately 39.8° (111), 46.2° (200), and 67.5° (220). The crystallite size should be estimated from the average value obtained using these reflections. In the present supported system, the latter two reflections are weak and partially overlap with diffraction features of the Al O support, limiting their quantitative use. Consequently, the crystallite size 2 3 estimation is primarily based on the Pt(111) reflection at 39.8°. This also leads to a larger error in particle size determination using XRD.\nHAADF-STEM analysis reveals that Pt/T-10A still contains a certain number of small-sized particles less than 2 nm. The statistically derived STEM number-average diameter therefore emphasizes these small particles and primarily reflects the fine- particle population. Nevertheless, the contribution of subnano Pt clusters (which could not be effectively identified and measured) may be underestimated in particle size statistics, and purely geometric size metrics do not directly quantify the fraction of catalytically accessible Pt surface.\nTable R1. Particle size analysis of Pt/T-10A catalyst after DRM reaction at 800 °C for 100 h.\nParticle size value\nCharacterization method Particle size metric\n(nm)\nNumber-average\nHAADF-STEM 2.14\ndiametera\nHAADF-STEM Volume-average diameterb 7.21\nXRD Crystallite diameterc 10.34\na Number-average particle diameter was calculated by eq. (5). b Volume-average particle diameter was calculated by eq. (6). c Crystallite size was calculated by Scherrer equation eq. (7).\n∑𝑛 𝑛𝑑\n𝐷 = 𝑖=1 𝑖 𝑖 (5)\n[1,0] ∑𝑛 𝑛\n𝑖=1 𝑖\n∑𝑛 𝑛𝑑4\n𝐷 = 𝑖=1 𝑖 𝑖 (6)\n[4,3] ∑𝑛 𝑛𝑑3\n𝑖=1 𝑖 𝑖\n𝐾𝜆\n𝐷 = (7)\n𝛽COS𝜃\nwhere dᵢ denotes the diameter of an individual Pt nanoparticle determined from HAADF-STEM analysis, K is the shape factor (0.9), λ is the X-ray wavelength, β is the FWHM of the diffraction peak (in radians), and θ is the Bragg angle.\nTherefore, we additionally performed CO chemisorption measurements to directly probe the accessible surface area of Pt particles, and provide complementary information on Pt dispersion and surface availability. For the optimal catalyst, the equivalent particle diameters derived from CO chemisorption before and after the stability test are 1.98 and 2.13 nm, respectively, indicating only a minor change in the CO-accessible Pt surface after long-term operation (100 h). The particle sizes derived from CO chemisorption differ from the STEM surface-area-weighted diameter (D[3,2]) (Table R2). Similar discrepancies between CO chemisorption-derived sizes and STEM-based diameters have also been reported in previous studies.2-4 Specifically, D[3,2] is more sensitive to a small fraction of larger particles, whereas CO chemisorption predominantly reflects the population of catalytically accessible Pt sites associated with finely dispersed nanoparticles. In the present system, the larger Pt particles locate most plausibly on the Al O which provide weaker metal-support 2 3 interactions and thus offer less stabilization against Pt sintering during reaction. On the spent Pt/Al O catalyst after 20 h of operation (Supplementary Fig. 12), extensive 2 3 sintering of Pt particles is clearly observed.\nTable R2. Pt particle size metrics for Pt/T-10A catalyst before and after DRM stability testing.\nD[3,2]a Equivalent particle diameterb\nCatalyst\n(nm) (nm)\nPt/T-10A (reduced) 1.32 1.98\nPt/T-10A after DRM test\n4.09 2.13\n(800 °C, 100 h)\na Surface-area-average particle diameter (D[3,2]), calculated from HAADF-STEM particle size statistics using eq. (1). b Equivalent particle diameter estimated from CO chemisorption.\n∑𝑛 𝑛𝑑3\n𝐷 = 𝑖=1 𝑖 𝑖 (1)\n[3,2] ∑𝑛 𝑛𝑑2\n𝑖=1 𝑖 𝑖\nwhere dᵢ denotes the diameter of an individual Pt nanoparticle determined from HAADF-STEM analysis.\nIn short, CO chemisorption directly probes the accessible metal surface and therefore provides a more relevant descriptor for discussing catalytic performance. The corresponding analysis supplemented in the “Structural and carbon evolution of spent catalysts” section, as well as in Supplementary Information.\nReference:\n1. Scardi, P. Diffraction Line Profiles in the Rietveld Method. Cryst. Growth Des. 20, 6903–6916 (2020).\n2. Wang, B. et al. Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO catalysts. Appl. Catal. B Environ. 238, 328–338 (2018).\n2\n3. An, K. et al. A highly selective catalyst of Co/La Ga O for CO hydrogenation to 4 2 9 2 ethanol. J. Energy Chem. 56, 486–495 (2021).\n4. Kang, S. B. et al. Ostwald-ripening sintering kinetics of Pd-based three-way catalyst: Importance of initial particle size of Pd. Chem. Eng. J. 316, 631–644 (2017).\nLine 367-384 on Page 19-20:\nAfter the stability test at 800 °C for 100 h, pronounced Pt(111) signals appeared in the XRD pattern (Supplementary Fig. 11), indicating the presence of relatively larger Pt crystallites. HAADF-STEM analysis reveals that a dominant population of finely dispersed Pt nanoparticles is still retained (Supplementary Fig. 13 and Supplementary Table 5). The observed larger Pt particles are most plausibly distributed on Al O and 2 3 formed via sintering during the reaction, an interpretation further supported by the extensive sintering observed for the Pt/Al O catalyst after 20 h (Supplementary Fig. 2 3 12). The Pt crystallite size estimated from the Scherrer equation is 10.34 nm, while the volume-average particle diameter (D[4,3]) derived from STEM analysis is approximately 7.21 nm. This discrepancy likely arises because the Scherrer-derived XRD size reflects the largest Pt crystallites that produce resolvable diffraction peaks owing to their limited long-range order, whereas the volume-average diameter is mainly influenced by a small fraction of large particles within a broad size distribution. To directly quantify the accessible metal surface, CO chemisorption measurements were conducted. The results show that the accessible Pt surface area decreases slightly after the stability test, from 4.07 to 3.75 m2 g-1 (Supplementary Table 6), consistent with the sustained catalytic performance under DRM conditions.\nLine 77-86 on Page 5 in Supplementary Information:\nCO pulse chemisorption measurements were carried out on a Micromeritics AutoChem III 2930 instrument. For the fresh catalyst, 100 mg of catalyst was loaded into a quartz reactor and reduced under a flow of 10% H /Ar (40 mL min-1) at 400 °C 2 for 1 h with a heating rate of 10 °C min-1. The catalyst was then cooled to 50 °C under Ar flow, and successive CO pulses were introduced until no further CO uptake was detected in consecutive pulses. For the spent catalyst measurement, it was firstly treated under flowing Ar at 200 °C to remove adsorbed species, including physisorbed water and other residual surface adsorbates, followed by cooling to 50 °C under Ar flow. CO pulse chemisorption was then carried out at 50 °C following the same protocol as for the fresh catalyst.\nLine 338-351 on Page 28-29 in Supplementary Information:\nSupplementary Table 5. Particle size analysis of Pt/T-10A catalyst after DRM reaction at 800 °C for 100 h.\nParticle size value\nCharacterization method Particle size metric\n(nm)\nNumber-average\nHAADF-STEM 2.14\ndiametera\nHAADF-STEM Volume-average diameterb 7.21\nXRD Crystallite diameterc 10.34\na Number-average particle diameter was calculated by eq. (5). b Volume-average particle diameter was calculated by eq. (6). c Crystallite size was calculated by Scherrer equation eq. (7).\n∑𝑛 𝑛𝑑\n𝐷 = 𝑖=1 𝑖 𝑖 (5)\n[1,0] ∑𝑛 𝑛\n𝑖=1 𝑖\n∑𝑛 𝑛𝑑4\n𝐷 = 𝑖=1 𝑖 𝑖 (6)\n[4,3] ∑𝑛 𝑛𝑑3\n𝑖=1 𝑖 𝑖\n𝐾𝜆\n𝐷 = (7)\n𝛽COS𝜃\nwhere dᵢ denotes the diameter of an individual Pt nanoparticle determined from HAADF-STEM analysis, K is the shape factor (0.9), λ is the X-ray wavelength, β is the FWHM of the diffraction peak (in radians), and θ is the Bragg angle.\nSupplementary Table 6. CO chemisorption results of Pt/T-10A catalyst before and after DRM stability testing.\nCO uptake (V ) Pt dispersion Pt surface area\nm\nCatalyst\n(cm3 g-1, STP) (%) (m2 g-1)\nPt/T-10A (reduced) 1.89 57.20 4.07\nPt/T-10A after DRM test\n1.75 53.10 3.75\n(800 °C, 100 h)\nComment 2:\nThere is inadequate detail on the Pt deposition procedure. What Pt precursor was used (chloroplatinic acid)? What was its purity? “Impregnation” is too vague; if it was incipient wetness impregnation, what pore volume of solution was used per mass of support? How was the contacted slurry dried and pre-treated (times, temperatures, ramp rate, flow rates and composition of gases)? Without this detail it would be very difficult for another lab to replicate the synthesis.\nResponse 2:\nWe thank you for this thoughtful and constructive comment. In the revised manuscript, we have added a more detailed description of the Pt impregnation procedure in the Methods section, including precursor information, impregnation conditions, and post-treatment steps, to improve clarity and reproducibility.\nLine 635-654 on Page 33:\nThe Pt catalysts were prepared by incipient wetness impregnation (IWI) using Al O , TiO , or T-xA as supports. Chloroplatinic acid hexahydrate (H PtCl ·6H O, Pt 2 3 2 2 6 2 content 37%) was used as the Pt precursor. Prior to impregnation, the pore volume of each support was determined by measuring its saturated water uptake. The resulting pore volumes were 0.83, 1.62, 1.80, 1.72, and 1.74 mL g-1 for TiO , T-3A, T-10A, T- 2 20A, and Al O , respectively. For each catalyst, 1 g of support and an aqueous 2 3 H PtCl ·6H O solution with a concentration of 100 mg mL-1 were employed. To 2 6 2 achieve a nominal platinum loading of 3 wt% (Supplementary Fig. 24), 835 μL of the H PtCl ·6H O solution was first transferred into a 5 mL centrifuge tube, followed by 2 6 2 the addition of deionized water to adjust the total solution volume to match the pore volume of the corresponding support. Specifically, additional water volumes of 785, 965, 885, and 905 μL were added for T-3A, T-10A, T-20A, and Al O , respectively. 2 3 The resulting solutions were ultrasonicated for 10 min until a homogeneous solution was obtained. The impregnation solution was then added dropwise to the support under continuous manual stirring with a glass rod to ensure uniform distribution of the precursor throughout the pore network. After impregnation, the samples were kept under static conditions at room temperature for 2 h. The impregnated solids were subsequently dried in a vacuum oven at 80 °C for 10 h, followed by calcination in a muffle furnace at 350 °C for 2 h with a heating rate of 2 °C min-1 under static air. The resulting catalysts were denoted as Pt/A, Pt/T, and Pt/T-xA, respectively.\nReviewer #3:\nAfter reviewing the modifications incorporated in the first revision, I have observed a distinct improvement in the paper's quality. The authors have diligently taken into account the suggestions provided by both my colleagues and me during the previous review."}, {"round": 3, "reviewer_comments": {"reviewer_2": "The additional XRD, STEM, and chemisorption results and analysis now bring the characterization of the catalysts up to the high standards of the journal. The additional detail on preparation is now adequate."}, "author_response": ""}]

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