bluuebunny/crossref_metadata_2025_split huggingface dataset:
Operando Electrochemical Raman Spectroscopy Studies of Working Electrodes in (photo)Electrocatalytic Water Splitting
Authors: Qiu Jingjing , Lin Timothy , Yap Kyra M. K. , Jaramillo Thomas F. , Nielander Adam C. 
Published: December 2024

Raman spectroscopy has been applied as a vibrational spectroscopic technique in the field of chemical, materials, and life sciences. Recently, the operando electrochemical Raman spectroscopy has received more research attention for the characterizations of working electrodes in (photo)electrochemical catalysis. This technique allows for the characterization of the fate of electrocatalysts on the surface of the working electrodes under electrochemical reaction conditions, which is crucial to determine the chemical identify of the electrocatalysts.
We apply the operando electrochemical Raman spectroscopy to study the anodes and cathodes in the (photo)electrocatalytic water splitting process, which is an important process to generate the clean energy hydrogen (H2) gas from water using solar energy and electricity. Specifically, we study the stability of the electrocatalyst molybdenum sulfide (MoS2) on silicon (Si) photocathode for the hydrogen evolution reaction (HER) and the electrochemical transformation of the electrocatalyst cobalt hydroxide (Co(OH)2) on nanostructured gold (Au) photoanode for the oxygen evolution reaction (OER). We have identified the correlation between the morphological changes and vibrational features of the MoS2 layer and detected the potential-dependent vibrational features of the Co(OH)2 film.
Investigating the Impact of Pt(hkl) Surface Structure on Electrochemical Double Layer Capacitance: Aimd Simulations and Experimental Insights
Authors: Chaudhary Payal , Nouri Mohammad Reza , Alexandrov Vitaly 
Published: December 2024

A comprehensive understanding of the electrical double layer (EDL) properties is essential to engineer electrochemical systems. The classical theory of EDL can reasonably explain experimental observations for only a few ideal systems like the liquid metal mercury electrodes, which are not suitable for practical applications. The EDL at solid electrodes, which are often used in electrochemical energy systems, have non-trivial dependences from several factors such as the electrode structure, its chemical composition, and complex interactions between the electrode surface and electrolyte species. Taking these factors into account requires a more detailed description of the EDL than that provided by the classical EDL theory.
In this study, we focus on the double layer capacitance as a key property of the EDL to rationalize experimental measurements of the capacitance as a function of the electrode surface structure. We employ ab initio molecular dynamics simulations to explicitly model several Pt(hkl)/water interfaces considering a series of flat and stepped surfaces at the potential of zero charge. We find that the orientation of water dipole moments at the interface depends strongly on the surface atomic structure, which can then influence the EDL capacitance. Our results suggest that simply by introducing surface defects such as steps on the Pt surface, the EDL capacitance can be varied significantly. We discuss our computational results in light of recent experimental data reported in J. Am. Chem. Soc. 2024, 146, 6, 3883–3889 and prior studies. We believe that the obtained insights are essential in advancing the fundamental understanding of the effect of electrode atomic structure on the basic electrochemical properties of electrocatalytic systems.
Predicted Current Density Response Versus Applied Potential for Five Crystallographic IrO2 Facets: Comparison with Thin Film Experiment
Authors: Kwon Soonho , Stoerzinger Kelsey A , Rao Reshma R , Qiao Liang , Goddard William A , Shao-Horn Yang 
Published: December 2024

Iridium oxide (IrO2) stands out as the most effective catalyst for the oxygen evolution reaction (OER), a pivotal component of proton exchange membrane (PEM) electrolyzers. Despite its exceptional catalytic prowess, the kinetics of this reaction still impose limitations on the efficient production of green H2, thereby inflating costs and impeding broader commercialization. The catalytic activity of IrO2 for OER is influenced by its local chemical and atomic environment, wherein distinct crystallographic facets with unique atomic arrangements can induce significant variations even with the same bulk composition.
In this study, we examine the OER performance across five distinct rutile IrO2 facets. Through DFT calculations, we predict cyclic voltammetry (under the water oxidation potential) and compare directly to the results to experiments conducted on IrO2 thin films for validation. Unlike pure metallic systems characterized by degenerate active sites resulting in broad single redox peaks, or homogeneous systems where redox reactions occur at metallic centers, active sites on metal oxide surfaces exhibit localization yet remain interconnected via various types of oxygen bonds. This unique attribute introduces additional considerations that must be included to interpret redox behavior, because interactions between adjacent intermediates alter their identities differently for different applied potentials. We find that multiple redox features can overlap while a single type of redox couple can be associated with multiple redox features.
To elucidate the OER activity under operational conditions (> 1.23 VRHE), we conducted grand canonical calculations to explicitly capture the dependence of reactions on the applied potential, with particular emphasis on non-electrochemical steps such as O-O coupling. Through the construction of various possible OER pathways and amalgamating their energy landscapes into a unified microkinetic scheme under steady-state assumptions, we successfully replicate the experimental OER current density for each of the five facets. Our analysis unveils mechanistic disparities between nucleophilic attack and direct oxo coupling across facets, predicting rates as a function of applied potential and identifying the rate-limiting steps.
Our approach provides a thorough comprehension of the OER mechanism at the atomic level, offering valuable insights into the structural characteristics that enhance or inhibit the OER activity of IrO2. We expect these insights to have implications for understanding the structural effects on other heterogeneous catalysts which should aid the development of more efficient electrocatalysts.
(Invited) Operando Probes of Site Densities, Energetics and Activity in Oxygen Evolution Catalysis
Authors: Stephens Ifan 
Published: December 2024

Theoretical studies have revealed the kinetics of oxygen evolution are controlled by the binding energies of reaction intermediates. However, those simulations are based on idealised single crystal structures. Little is known about the catalytically active phases on high surface area catalysts.
In this contribution I will show how operando optical spectroscopy of oxygen evolution catalysts can yield (i) site densities (ii) binding energies of intermediates and (iii) turnover frequencies. We reveal the role of adsorbate-adsorbate interactions on state-of-the-art iridium2-4 and cobalt5 based catalysts, including molecular catalysts and oxides. I will correlate electrochemical measurements to operando optical spectroscopy, X-ray absorption spectroscopy and secondary ion mass spectrometry. Density functional theory measurements provide a molecular scale explanation for the observed phenomena.

Man, I. C., Su, H. Y., Calle-Vallejo, F., Hansen, H. A., Martínez, J. I., Inoglu, N. G., Kitchin, J., Jaramillo, T. F., Nørskov, J. K. & Rossmeisl, J. ChemCatChem 3, 1159, (2011).

Liang, C., Rao, R. R., Svane, K., Hadden, J. H. L., Moss, B., Scott, S. B., Sachs, M., Murawski, J., Frandsen, A., Riley, D. J., Ryan, M. P., Rossmeisl, J., Durrant, J. R. & Stephens, I. E. L. Nature Catalysis, (2024 in press).

Bozal-Ginesta, C., Rao, R. R., Mesa, C. A., Wang, Y. X., Zhao, Y. Y., Hu, G. F., Anton-Garcia, D., Stephens, I. E. L., Reisner, E., Brudvig, G. W., Wang, D. W. & Durrant, J. R. J. Am. Chem. Soc. 144, 8454, (2022).

Liang, C., Katayama, Y., Tao, Y., Morinaga, A., Moss, B., Celorrio, V., Ryan, M., Stephens, I. E. L., Durrant, J. R. & Rao, R. R. J. Am. Chem. Soc., (2024).

Moss, B., Svane, K. L., Nieto-Castro, D., Rao, R. R., Scott, S. B., Tseng, C., Sachs, M., Pennathur, A., Liang, C., Oldham, L. I., Mazzolini, E., Jurado, L., Sankar, G., Parry, S., Celorrio, V., Dawlaty, J. M., Rossmeisl, J., Galán-Mascarós, J. R., Stephens, I. E. L. & Durrant, J. R. J. Am. Chem. Soc., (2024).
(Invited) Investigation of Anion Role during Electrochemical CO2 Reduction on Copper Sulfide (CuS) by Potential-Step Method
Authors: Yamaguchi Akira , Taga Hisanobu , Miyauchi Masahiro 
Published: December 2024

One of the candidate materials as CO2 reduction electrocatalysts is metal sulfide, generally because it possesses multiple adsorption sites to overcome scaling relationship. Furthermore, metal sulfide has unique redox property that not only metal sites but anion (sulfur) sites are redox active. To use this property efficiently, this work focused on potential-step method, in which two different electrode potential are applied to an electrode during CO2 reduction process. Previous electrochemical CO2 reduction works using metal copper (K. Kimura et al., ACS Catal., 10, 8632-8639, 2020) and tin sulfide (A. Woldu et al., Angew. Chem. Int. Ed., 62, 2023) electrodes as catalysts clearly demonstrated the usefulness of this method for CO2 reduction, however, its effect on anion behavior and CO2 reduction intermediate is under exploration. In this work, using copper sulfide (CuS) as a model compound, anion role on CO2 reduction reaction by potential-step method on metal sulfide was investigated.
CuS was synthesized with solvothermal method using Cu(NO3)2, thioacetamide, and ethylene glycol as precursor solution. X-ray diffraction (XRD) and Raman measurements revealed that the obtained CuS possesses hexagonal structure. To prepare working electrode, dispersion solution of CuS in water and ethanol containing Sustainion as a binder was dropped onto carbon paper electrode. Electrochemical CO2 reduction properties were examined using H-type cell and 0.1 M KHCO3 aq. as an electrolyte. Platinum mesh and Ag/AgCl (sat. KCl) were used as counter and reference electrodes, respectively.
By applying potential step method, selectivity for formic acid (HCOOH) was increased compared with conventional constant-potential method. XRD and X-ray photoelectron spectroscopy measurement revealed that Cu redox state was changed between Cu0 and Cu+ states during cathodic and anodic potential application, respectively. Furthermore, combining in situ Fourie Transformation Infrared spectroscopy and controlling experiment using Cu0 electrode, Cu2O, and Cu0 in the presence of S2- ion, this work proposed possible intermediate species and how they were affected by anions involved in the reaction to generate specific products. Namely, surface-adsorbed sulfur enhanced the adsorption of H+ ion and contributed to promoting all the reaction, while bulk sulfur stabilized CO intermediate to increase HCOOH selectivity. In addition, existence of oxygen generated Cu+ sites and resulting Cu+/Cu0 interface contributed to producing multi-carbon compounds. Our results indicated that the regulation of anion behavior by potential-step method is one of the promising strategies to control product selectivity of electrochemical CO2 reduction.
Electrocatalyst Design for Carbon Dioxide Co-Reduction with Nitrate for Sustainable Synthesis of Urea
Authors: Chen Yu-Han , Roiron Camille , Atanassov Plamen 
Published: December 2024

The electrochemical co-reduction of nitrate (NO3
-) and carbon dioxide (CO2) for the synthesis of urea has drawn much research focus recently because it creates value-added products from environmentally hazardous pollutants. Urea is the major ingredient of fertilizer, that is currently produced through the Bosch-Meiser process starting from ammonia (NH3) and carbon dioxide (CO2), in which ammonia is produced through the Haber-Bosch process, leading to significantly high energy consumption and CO2 emissions. Urea electrosynthesis is a complex 16e-, 12H+ transfer reaction with multiple possible by-products such as H2, CO, HCOOH, NO2
-, NH3, etc., making the electrocatalyst design toward urea selectivity a big challenge.
To reliably quantify the urea produced, we present an updated method for urea quantification using the diacetylmonoxime-thiosemicarbazide (DAMO-TSC) method while excluding the interference of NO2
- by-product. We believe this method can guide the electrocatalysis community to establish an updated protocol and avoid false positive/overestimating results.
We will then present a catalyst designed for urea electrosynthesis consisting of Pd nanoparticles in nanoscale proximity to atomically dispersed Fe-Nx sites on a carbon matrix (FeNC). Our group has previously presented Pd nanoparticles and FeNC materials as efficient catalysts for CO2 and NO3
- reduction respectively. Their association at the nanoscale demonstrates over 20% urea faradaic efficiency at -0.5 V (vs RHE) with 100% N-selectivity (All by-products contain nitrogen). These very promising results provide us with the baseline to elucidate the role of individual active sites on the C-N coupling mechanism. To this effect, reaction intermediates of CO2 and NO3
- co-reduction are investigated by in-situ vibrational spectroscopy (Raman, infrared). This study validates the approach of tuning electrocatalysts through mechanistic studies realizing CO2 / NO3
- co-reduction.
Reference:

Murphy, E., Liu, Y., Matanovic, I., Rüscher, M., Huang, Y., Ly, A., Guo, S., Zang, W., Yan, X., Martini, A., Timoshenko, J., Cuenya, B. R., Zenyuk, I. V., Pan, X., Spoerke, E. D., & Atanassov, P. Elucidating electrochemical nitrate and nitrite reduction over atomically-dispersed transition metal sites. Nat Commun 14, 4554 (2023).

Guo, S., Liu, Y., Murphy, E., Ly, A., Xu, M., Matanović, I., Pan, X., & Atanassov, P. Robust palladium hydride catalyst for electrocatalytic formate formation with high CO tolerance. Applied Catalysis. B, Environmental, 316, 121659. (2022).

Huang, Y., Wang, Y., Liu, Y., Ma, A., Gui, J., Zhang, C., Yu, Y., & Zhang, B. Unveiling the quantification minefield in electrocatalytic urea synthesis. Chemical Engineering Journal, 453, 139836. (2023).
Electrochemical CO2 Reduction Reaction to Methanol on a Molecular Cobalt Catalyst
Authors: Menga Davide , Yu Sunmoon , Shao-Horn Yang 
Published: December 2024

Our society is currently facing critical challenges regarding CO2 emissions and drastic changes in the way we produce energy, chemicals and materials are required in order to tackle global warming. The electrochemical reduction of CO2 is a key reaction in order to reduce our carbon footprint and a great scientific effort is being made to improve our knowledge and understanding about this complicated process. Recently, cobalt phthalocyanine (CoPc) has drawn tremendous attention due to its capability to electrochemically reduce CO2 and CO to methanol (1-6), a key molecule in the chemical manufacturing industry. Because of its well-defined structure, CoPc provides a model platform to understand reaction mechanism and rationally improve the catalytic activity and stability. In our recent work, through kinetic isotope effect studies and electrokinetic analyses, we identified the protonation of adsorbed CHO as the rate determining step (RDS) for CO2-to-methanol conversion and we showed that the hydration shell of more acidic alkali cations can enhance CO2-to-methanon kinetics via faster proton-coupled electron transfer (in the order Li+ > Na+ > K+ > Cs+). This conclusion was supported by density functional theory calculations and molecular dynamics simulations. In this contribution, the reaction mechanism of CO2-to-methanol electroreduction will be discussed, with a particular focus on how proton-coupled electron transfer kinetics and the stability of reaction intermediates can be tuned in order to maximize the faradaic efficiency for methanol production. Moreover, we will discuss the impact of different reaction conditions on the stability of the CoPc catalyst and possible mitigation strategies will be proposed.
References:

Y. Wu, Z. Jiang, X. Lu, Y. Liang and H. Wang, Nature, 575, 639 (2019).

C. L. Rooney, M. Lyons, Y. Wu, G. Hu, M. Wang, C. Choi, Y. Gao, C.-W. Chang, G. W. Brudvig, Z. Feng and H. Wang, Angewandte Chemie International Edition, 63, e202310623 (2024).

J. Li, B. Shang, Y. Gao, S. Cheon, C. L. Rooney and H. Wang, Nature Synthesis, 2, 1194 (2023).

J. Su, C. B. Musgrave, Y. Song, L. Huang, Y. Liu, G. Li, Y. Xin, P. Xiong, M. M.-J. Li, H. Wu, M. Zhu, H. M. Chen, J. Zhang, H. Shen, B. Z. Tang, M. Robert, W. A. Goddard and R. Ye, Nature Catalysis, 6, 818 (2023).

E. Boutin, M. Wang, J. C. Lin, M. Mesnage, D. Mendoza, B. Lassalle-Kaiser, C. Hahn, T. F. Jaramillo and M. Robert, Angewandte Chemie International Edition, 58, 16172 (2019).

L. Yao, K. E. Rivera-Cruz, P. M. Zimmerman, N. Singh and C. C. L. McCrory, ACS Catalysis, 14, 366 (2024).

Figure 1
Preparation and Characterization of Ni/YSZ-Based Tubular Electrochemical Reactor for SOEC Methanation
Authors: Horiguchi Genki , Yamaguchi Toshiaki , Toriumi Hajime , Tateno Hiroyuki , Bagarinao Katherine Develos , Kishimoto Haruo , Mochizuki Takehisa 
Published: December 2024

Co-electrolysis of CO2 and steam using solid oxide electrolysis cells (SOECs) can produce syngas (CO and H2 mixture with various ratios), which is further utilized for the synthesis of hydrocarbon fuels using a catalyst. The combination of SOEC and catalytic fuel synthesis processes can offer an environmentally friendly fuel production process. Ni with yttria-stabilized zirconia (Ni/YSZ) is a typical material utilized for SOEC fuel electrodes. Additionally, Ni metal on YSZ support can also be used as a catalyst for methane production (methanation). In this study, a Ni/YSZ-based tubular electrochemical reactor is developed for the methanation process. The correlations between electrochemical and methanation properties of the prepared reactor will be reported in this presentation.
This study is partly based on results obtained from a project, JPNP21022, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
Novel Front Contacts for Hydrophobic Gas Diffusion Layers Enable High Energy Efficiency and Durability for Electrochemical CO2 Reduction to C2+ Products.
Authors: Goldman Maxwell , Krall Eric , Marufu Michell , Jaffer Shaffiq A. , Sarkar Amitava , Fleischer Maximilian , Simon Elfriede , Wong Andrew Allen , Baker Sarah 
Published: December 2024

Electrochemical CO2 reduction (eCO2R) is an attractive route to mitigate the rise in the global CO2 concentration while producing value-added chemicals. Ethylene (C2H4) is one such product of eCO2R which is an essential industrial precursor with a prominent global market of $230 billion. The large-scale implementation of C2H4-selective CO2 electrolyzers is still challenge due to the low energy efficiencies causes by high ohmic resistances when either employing a hydrophobic gas diffusion layer such as expanded polytetrafluoroethylene (ePTFE), or employing a near neutral catholyte in a single-gap electrolyzer. In this work, we have developed a novel front contact for a CO2 electrolyzer in a zero-gap architecture for electrically insulating gas diffusion layers. This front contact layer allows for incorporating an ePTFE gas diffusion layer while achieving similar full cell voltages as carbon-based gas diffusion electrodes; this configuration also has the added benefits of increased cell stability and selectivity for ethylene. By tailoring the catalyst layer, gas diffusion medium, and operating conditions for a zero-gap ePTFE gas diffusion layer, we were able to achieve a full cell voltage of 2.5 V, with faradaic efficiencies of 48% for ethylene and over 90% faradaic efficiency for reduced carbon species at 200 mA cm-2 and 25 cm2 geometric area cell. This work points towards strategies for developing a scalable, stable, and high energy efficiency eCO2R for C2+ products.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Reactive Capture of CO2 via Amino Acid
Authors: Xiao Yurou Celine , Sun Siyu , Zhao Yong , Miao Rui Kai , Fan Mengyang , Lee Geonhui , Chen Yuanjun , Gabardo Christine M. , Yan Yu , Qiu Chenyue , Guo Zunmin , Wang Xinyue , Papangelakis Panagiotis , Huang Jianan Erick , Li Feng , O'Brien Colin P. , Kim Jiheon , Han Kai , Corbett Paul J. , Howe Jane , Sargent Edward H. , Sinton David 
Published: December 2024

The electrochemical production of carbon monoxide (CO) from carbon dioxide (CO2) has conventionally relied on gas-phase CO2 electrolysis with complex upstream capture and downstream gas separation processes. Reactive capture of CO2 – an integrated approach that combines CO2 capture and electrochemical conversion – uses chemisorbed CO2 directly as the feedstock and thereby avoids CO2 purification and associated costs.
To date, reactive capture has relied on hydroxide-based capture solutions (e.g. potassium hydroxide (KOH)) suitable for direct air capture (DAC) processes or amines (e.g. monoethanolamine (MEA)) that have been conventionally used for point source capture. However, in hydroxide-based systems that capture CO2 in the form of carbonate, the CO Faradaic efficiency (FE) is limited to 50% due to the interaction between in-situ regenerated CO2 and local hydroxides that reduce CO2 availability at the cathode. Amine-based reactive capture can overcome this selectivity challenge when CO2 is captured in the form of carbamate and bicarbonate; compared to carbonate, these forms of chemisorbed CO2 require less electron-coupled protons to regenerate in-situ CO2, and thus yield more CO2 at the cathode. However, conventional amines are volatile and have poor oxygen tolerance, rendering them inapplicable to oxygen-rich CO2-lean conditions.
Here, we report amino acid salt (AAS)-based reactive capture of CO2 that exceeds the CO energy efficiency (EE) achieved in amine- and hydroxide- based systems. The AAS capture solution, potassium glycinate (K-GLY), contains amino functional groups for efficient CO2 capture while offering advantages including oxygen tolerance, low vapor pressure, and low toxicity. We synthesized a nickel single atom (Ni-N/C) catalyst to improve conversion efficiency, optimized the capture solution composition to reduce the electrolysis overpotential at high current densities, and elevated the operating temperature and pressure to increase availability of dissolved in-situ CO2 at the cathode. We achieve CO production with 64% CO FE and a measured full cell voltage of 2.74 V at 50 mA cm-2, resulting in an CO EE of 31% and an energy intensity of 40 GJ tCO-1. The feasibility of the full reactive capture process was demonstrated with both simulated flue gas and direct air input.