bluuebunny/crossref_metadata_2025 huggingface dataset:
Realization High-Voltage Stabilization of O3-Type Layered Oxide Cathodes for Sodium-Ion Batteries by Sn Simultaneously Dual Modification
Authors: Song Tengfei , Chen Lin , Gastol Dominika , DONG Bo , Marco José F , Berry Frank J , Slater Peter R. , Reed Daniel , Kendrick Emma
Published: February 2024

The total global production of lithium-ion batteries (LIBs) used in electric vehicles and stationary energy storage devices has increased sharply to reach the targeted Net Zero by 2050. This leads to concerns about the future and long-term availability and cost of critical raw materials (cobalt, nickel, lithium and copper) employed in LIBs. Therefore, alternative new-generation batteries with comparable performance but using less critical raw materials are needed.

Sodium-ion Batteries (NIBs) offer a wealth of possibilities for inexpensive and sustainable energy storage devices. To maximize their potential, new cathode materials with high energy densities and stable structures are required. Cobalt-free sodium transition metal oxides of O3 type are a predominant cathode for NIBs due to their appreciable specific capacity, reduction in the use of critical elements, and the potential to rival LiFePO4 in terms of energy density. However, rapid capacity fading caused by serious structural and interfacial degradation hamper this process.

Herein, we provide a novel Sn-modified O3-type NaNi1/3Fe1/3Mn1/3O2 cathode with improved high-voltage stability by bulk Sn doping and surface coating simultaneously. The bulk substitution of Sn4+ stabilizes the crystal structure by alleviating the irreversible high voltage phase transition and lattice structure degradation. In the meantime, the spontaneously formed tin rich surface layer effectively inhibits surface parasitic reactions and improves interfacial stability during cycling. As a result, the Sn-modified NaNi1/3Fe1/3Mn1/3O2 cathode exhibited excellent cycling performance by an almost doubled capacity retention increase after 200 cycles within 2.0-4.1V. The influence of Sn modification on the crystal structure and electrochemical properties has been investigated for the first time, and the mechanism was studied through an extensive analysis by in situ XRD, HRTEM, FIB-SEM, XPS and Mössbauer spectroscopy.

This work offers an industrially feasible strategy to simultaneously stabilize the bulk structure and interface for O3-type layered cathodes for SIBs and raises the possibility of similar effective strategies to be employed for other energy storage materials

Figure 1
The Effect of Oxygen Vacancies on Oxygen Evolution: The Case of BiVO_4
Authors: Österbacka Nicklas , Ouhbi Hassan , Wiktor Julia , Ambrosio Francesco
Published: February 2024

Bismuth vanadate, BiVO4, is one of the most promising photoanode materials for the challenging oxygen evolution half-reaction in solar-driven water splitting. The material tends to be rich in oxygen vacancies, which strongly affects its photoelectrochemical properties. Experimental evidence suggests that oxygen deficiency is beneficial for the oxygen evolution reaction in the material, but the mechanism behind this enhancement is still controversial. The defects could be involved directly in the reaction if present at the surface, and the occupancy of the defect states could also play an important role. The latter is seldom considered in mechanistic studies, however.

Using density functional theory, we show that the surface oxygen vacancy in bismuth vanadate is stablest when fully ionized. We investigate how this affects the oxygen evolution mechanism by mapping out the stablest reaction intermediates and compare the resulting pathway with those on the unionized oxygen-deficient surface as well as the defect-free material. The overpotentials required to drive the reaction in each case are computed to quantify whether or not vacancy formation, and subsequent ionization, improves the thermodynamics of oxygen evolution.
Strategies for Sustainable Fuel Production Via Photoelectrochemical Synthesis
Authors: Im Sejin , Lim Yoongu , Surendran Subramani , Sim Uk
Published: February 2024

Developing sustainable energy is highly imperative for humankind owing to the drastic rise in world population and the proportional rise in energy demand at the expense of energy consumption. Various efforts have been made to explore, generate, store, and utilize renewable energy to replace fossil fuels. Among them, solar energy is considered an alternative to fossil fuels because it is inexhaustible, clean, cost-effective, and versatile. Interestingly, this prime source provides massive energy that is high enough (1.9 × 108 TWh/yr) to counterattack global energy consumption (1.3 × 105 TWh/yr).

Photoelectrochemistry has been considered a promising route to harness this incredible energy by producing sustainable energy fuels and carriers such as hydrogen, hydrocarbon, and ammonia. PEC systems have the great advantages of simple process steps and very low environmental burdens. However, this technology must overcome many challenges regarding commercial applications, particularly in fabricating electrode materials for PEC water splitting.

One of the most important challenges to overcome this problem is discovering efficient catalysts for implementing photoelectrochemical (PEC) fuel production. A critical requirement for outstanding catalysts is an ability to boost the kinetics of a chemical reaction and durability against electrochemical and photo-induced degradation. Moreover, the charge-separation and transfer mechanism are the two paramount properties to consider while designing photoelectrodes. Briefly, the semiconductor materials to be used in PEC water splitting must possess a conduction band potential more negative than the reduction edge of hydrogen and a valence band potential positive to actuate water oxidation. In practice, the photocurrent density and solar-to-hydrogen (STH) efficiency of the n-type semiconductors are far behind the theoretical values.

To address this critical and long-standing technical barrier, I have focused on an intense search for efficient, durable, and inexpensive alternative catalysts with moderate band gap, efficient charge excitation-separation property, and high solar energy conversion efficiency for photoelectrochemical systems of water splitting, hydrocarbon conversion, and ammonia production.

Keywords

: Photoelectrochemistry, Sustainable Energy, Water Splitting, Ammonia synthesis, Urea synthesis, Hydrocarbon
A Urea Modified Ternary Aqueous Electrolyte with Tuned Intermolecular Interactions and Confined Water Activity for Highly Stable Zinc-Ion Batteries
Authors: Wang Ziqing , Mullins Charles Buddie
Published: February 2024

Aqueous zinc-ion batteries (ZIBs) have gained attention as potential energy storage devices due to their high safety.1 However, the narrow electrochemical window and unfavorable side reactions (i.e., hydrogen and oxygen evolution reactions) induced by water decomposition restrict their development.2,3 Thus, constraining water activity is necessary to enhance stability and enlarge electrochemical window. In this study, we prepare a 2.9 m (mol kgsolvent
−1) Zn(ClO4)2−CO(NH2)2−H2O ternary aqueous electrolyte with restricted water activity at room temperature. Raman, Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) characterization techniques suggest strong intermolecular interactions between CO(NH2)2 and H2O, which decrease the free H2O molecules and reduce their associated activity to suppress the parasitic reactions at the electrodes. Density functional theory (DFT) calculations substantiate the strong hydrogen bonds between urea and water. Compared with eutectic electrolyte and water-in-salt electrolyte, this aqueous electrolyte exhibits a high ionic conductivity (6.83 mS cm−1) as conventional aqueous electrolytes without sacrificing the voltage window (2.5 V). Furthermore, DFT computations reveal the preferential adsorption of urea molecules onto the zinc surface, mediating zinc deposition process. The reduction of urea generates a robust organic solid electrolyte interphase (SEI), promoting homogeneous zinc deposition on the anode and hindering parasitic reactions. Consequently, this ternary aqueous electrolyte not only imparts Zn/Zn symmetric cells with prolonged cycling stability exceeding 1000 h at various current densities but also endows zinc−vanadium batteries a capacity of 250 mAh g−1 for 400 cycles at 1 A g−1. This finding highlights a promising approach for the development of stable aqueous zinc-ion batteries with an expanded electrochemical window.

Reference

A. Konarov et al. ACS Energy Letters
2018, 3 (10), 2620–2640.

C. Li et al. Joule
2022, 6 (8), 1733–1738.

J. Zhou et al. Advanced Materials
2021, 33 (33), 2101649.

Figure 1
Metastable Ni(I)-TiO2-X Photocatalyst: Self-Amplifying H2 Evolution from Plain Water without Noble Metal Co-Catalyst and Sacrificial Agent
Authors: Altomare Marco , Qin Shanshan , Saveleva Viktoriia A. , Badura Zdenek , Tomanec Ondrej , Mazare Anca , Zoppellaro Giorgio , Vertova Alberto , Taglietti Angelo , Minguzzi Alessandro , Ghigna Paolo , Schmuki Patrik
Published: February 2024

This contribution describes the self-assembling and self-activating nature of a TiO2 photocatalyst that generates hydrogen from water in the absence of sacrificial species or noble metal co-catalysts [1]. Such system forms when nanoparticles of reduced anatase TiO2 are illuminated in an aqueous Ni2+ solution [2,3]. UV illumination creates in-situ a Ni+/TiO2/Ti3+ photocatalyst that over time produces H2 at a higher rate. Thus, UV light is both the synthesis tool that forms this active metastable photocatalytic entity and the energy provider for this entity to enable H2 evolution from water.

Operando X-ray absorption (XAS) and electron paramagnetic (EPR) spectroscopies show that key to self-assembly and self-activation is the light-induced formation of defects in the semiconductor [4], which enables the formation of monovalent Ni+ surface states. Metallic nickel states, i.e., Ni0, do not form, neither in the dark (resting state) nor under illumination (active state). Once the catalyst is assembled, the Ni+ surface states act as electron relay for electron transfer to form H2 from water.

Self-amplifying reaction schemes of this type entail considerable potential for developing a new generation of photocatalysts via simple one-pot synthesis routes.

References

[1] M. Altomare, S. Qin, V.A. Saveleva, Z. Badura, O. Tomanec, G. Zoppellaro, A. Vertova, A. Taglietti, A. Minguzzi, P. Ghigna, P. Schmuki, under review.

[2] S. Qin, Z. Badura, N. Denisov, O. Tomanec, S. Mohajernia, N. Liu, S. Kment, G. Zoppellaro, P. Schmuki, Electrochem. Commun. 122 (2021) 106909.

[3] A. Naldoni, M. Altomare, G. Zoppellaro, N. Liu, Š. Kment, R. Zbořil, P. Schmuki, ACS Catal. 9 (2019) 345–364.

[4] E. Wierzbicka, X. Zhou, N. Denisov, J.E. Yoo, D. Fehn, N. Liu, K. Meyer, P. Schmuki, ChemSusChem. 12 (2019) 1900–1905.
Core-Shell and Yolk-Shell Nanocrystals for Hydrogen Production
Authors: Hsu Yung-Jung
Published: February 2024

With the inherently high degree of complexity, heterostructures composed of two or more materials joined in unique architectures may exhibit superior synergetic properties that are difficult or impossible to acquire from their individual constituents.[1-3] For semiconductor heterostructures, the relative band alignment of the constituents promotes effective charge separation to bring them desirable properties for photocatalysis applications. Among the different types of heterostructures, core-shell and yolk-shell nanocrystals have received particular interest due to their fascinating properties. Several representative works from our lab will be introduced to demonstrate the promising potentials of core-shell and yolk-shell nanocrystals for hydrogen production applications.

References

[1] Chun-Wen Tsao, Mei-Jing Fang, Yung-Jung Hsu*, “Modulation of interfacial charge dynamics of semiconductor heterostructures for advanced photocatalytic applications”, Coordination Chemistry Reviews
2021, 438, 213876 (Invited Review).

[2] Mei-Jing Fang, Chun-Wen Tsao, Yung-Jung Hsu*, "Semiconductor Nanoheterostructures for Photoconversion Applications", Journal of Physics D: Applied Physics
2020, 53, 143001 (Invited Review).

[3] Yi-An Chen, Yu-Ting Wang, Hyun Sik Moon, Kijung Yong, Yung-Jung Hsu*, "Yolk-shell nanostructures: synthesis, photocatalysis and interfacial charge dynamics", RSC Advances
2021, 11, 12288-12305 (Invited Review; selected as themed collections of Photocatalysis).
(Invited) Acid Stable Water Oxidation Catalysts for PEM Water Electrolysis
Authors: Nakamura Ryuhei
Published: February 2024

Water electrolysis is a promising method to produce hydrogen from renewable electricity. However, the development of 3d metal catalysts for the oxygen evolution reaction (OER) is a critical challenge, especially in the case of polymer electrolyte membrane (PEM) electrolyzers, which are considered to be one of the most efficient electrolysis systems. The scarcity of iridium required for these systems prevents their widespread deployment at the global terawatt scale, and therefore the development of alternative catalysts has been highlighted as a real bottleneck for water electrolysis.

In this talk, I will report on how the incorporation of Mn into the Co3O4 spinel lattice can result in a two order of magnitude increase in stability without compromising activity (1, 2). I will also report on how the lifetime of Mn-based catalysts in acid can be extended by modulating the lattice oxygen structure (3). Finally, I will discuss the performance of Mn-based OER catalysis under the actual conditions of PEM water electrolysis (3).

(1) A. Li, S. Kong, C. Guo, H. Ooka, K. Adachi, D. Hashizume, Q. Jiang, H. Han, J. Xiao, R. Nakamura, Enhancing the stability of cobalt spinel oxide towards sustainable oxygen evolution in acid, Nat. Catal., 2022, 5, 109-118, DOI: 10.1038/s41929-021-00732-9

(2) A. Li, H. Ooka, N. Bonnet, T. Hayashi, Y. Sun, Q. Jiang, C. Li, H. Han, R. Nakamura, Stable potential windows for long-term electrocatalysis by manganese oxides under acidic conditions, Angew. Chem., Int. Ed., 2019, 58, 5054-5058. DOI: 10.1002/anie.201813361

(3) S. Kong, et al (under review)
(Invited) Advances in Photon-Harvesting Technologies for Perovskite Absorbers and Water Splitting Reactions
Authors: Mathur Sanjay , Fischer Thomas
Published: February 2024

Hybrid halide perovskites have made significant progress in power conversion efficiencies (> 25 %) and high stability achieved through chemical engineering of the AMX3 composition. Compositional engineering of perovskite precursor inks minimizes batch-to-batch variations and fluctuation in PCE values, however the understanding of perovskite inks and solution behavior remains a key step towards the exploitation of solution-processed perovskite devices. Herein, a comprehensive 207Pb nuclear magnetic resonance spectroscopy (NMR) study performed on various lead perovskite precursor inks will be presented. The NMR data provide fresh insights in identifying molecular species that are invariably and predominantly formed in precursor mixtures to coexist with larger networks and colloids. The solution chemistry of PbI2+I- is dominated by the type of connectivity as edge- face- and corner-sharing (PbI6)-octahedra and their dimensionality. The trends in the 207Pb chemical shifts revealed dynamic equilibria in the inks that can be controlled by stoichiometry, nature of the solvents and temperature. Furthermore, perovskite precursor ink development can be applied to fabricate devices beyond the planar device structures, such as direct electrospinning of the three major perovskite solar cell components, namely, photo absorber, hole, and electron transport materials, as continuous single triaxial fibers of μm radial dimensions. These perovskite fibers lay the foundation of materials engineering for fabricating tiny solar cells, which can either be woven into fabrics or incorporated as single fibers to power wearables and a variety of devices or sensors, forming the internet of things. They are also suited for tandem PV-PEC set-up for solar-assisted photoelectrochemical production of hydrogen by water-splitting reactions.
(Invited) Tuning and Transferring Slow Photons for Unprecedented Visible Light Photocatalysis
Authors: Madanu Thomas L , Su Bao-Lian
Published: February 2024

Periodic structures with alternating refractive indices such as inverse opal photonic crystals are capable of reducing the group velocity of light such that this slowed light can be more efficiently harvested for highly enhanced solar energy conversion. However, the generation, the manipulation and, in particular, the practical applications of these slow photons remain highly challenging. Here, we report the first proof of concept on the ability to control, in an inverse opal TiO2-BiVO4 hetero-composite, the transfer of slow photons generated from the inverse opal photonic structure to the photocatalytically active BiVO4 nanoparticles for highly enhanced visible light photoconversion. Tuning the slow photon frequencies, in order to accommodate the electronic band gap of BiVO4 for slow photon transfer and for significantly improved light harvesting, was successfully achieved by varying the structural periodicity (pore size) of inverse opal and the light incidence angle. The photocatalytic activity of BiVO4 in all inverse opal structures, promoted by slow photon effect, reached up to 7 times higher than those in the non-structured compact films. This work opens new avenues for the practical utilization of slow photon effect under visible light in photocatalytic energy-related applications like water splitting and carbon dioxide reduction and in photovoltaics.
(Invited) Polymeric Carbon Nitride for Photocatalytic Overall Water Splitting
Authors: Shen Shaohua
Published: February 2024

Photocatalytic overall water splitting can be achieved using Z-scheme systems that mimic natural photosynthesis by combining dissimilar semiconductors in series. However, coupling well-suited H2- and O2-evolving components remains challenging. Here, we fabricate a Z-scheme system for photocatalytic overall water splitting based on boron-doped, nitrogen-deficient carbon nitride two-dimensional (2D) nanosheets. We prepare ultrathin carbon nitride nanosheets with varying levels of boron dopants and nitrogen defects, which leads to nanosheets that can act as either H2- or O2-evolving photocatalysts. Using an electrostatic self-assembly strategy, the nanosheets are coupled to obtain a 2D/2D polymeric heterostructure. Owing to their ultrathin nanostructures, strong interfacial interaction and staggered band alignment, a Z-scheme route for efficient charge-carrier separation and transfer is realized. The obtained heterostructure achieves stoichiometric H2 and O2 evolution in the presence of Pt and Co(OH)2 co-catalysts, and the solar-to-hydrogen efficiency reaches 1.16% under one-sun illumination.
(Invited) Chirality-Induced Spin Selectivity Enabling Efficient Spin-Dependent Oxygen Evolution Reaction and High-Performance Photoelectrochemical Water Splitting
Authors: Lee Hyungsoo , Lee Chan Uk , Yun Juwon , Jeong Wooyong , Jong Chang-Seop , Son Jaehyun , Park Young Sun , Jang Gyumin , Moon Subin , Moon Jooho
Published: February 2024

The sluggish and complex multi-step oxygen evolution reaction (OER) remains an obstacle to bias-free photoelectrochemical water-splitting systems. Several theoretical and experimental studies have suggested that OER efficiency can be significantly enhanced in chiral material-based photoanodes by utilizing the chirality-induced spin selectivity (CISS) phenomenon. The final product at the photoanode is the oxygen molecules, where the spin alignment of intermediate radicals is favorable to the generation of triplet 3O2 (most stable molecular oxygen species). Considering the energy difference between a singlet 1O2 and triplet 3O2, spin-dependent chemical reactions combined with the CISS phenomenon can play a crucial role in the OER process. Moreover, chiral material-based photoanodes are capable of paralleling spin distribution on the catalytic surface. The resulting spin-aligned intermediate radicals can promote the generation of spin-allowed triplet 3O2 over that of singlet oxygen, while hindering the formation of hydrogen peroxide, in turn leading to the enhanced STH efficiency of the overall PEC water-splitting system. In this regard, chiral materials (as a spin-filter layer) have been recognized as promising candidates for achieving a breakthrough in the solar-to-hydrogen efficiency of water-splitting devices. Herein, we report that the CISS phenomena can become an impressive approach by adopting chiral 2D organic-inorganic hybrid perovskites (OIHPs) as a spin-filtering layer on the 3D OIHP photoanode. Our chiral 2D OIHP-based water-splitting device achieved enhanced oxygen evolution performance with a reduced overpotential of 0.2 V, high fill factor, and increased photocurrent of 22 mA cm–2 at 1.2 VRHE compared to a device without a spin-filtering layer. For unbiased water splitting, a perovskite-based photocathode decorated with a spatially decoupled hydrogen evolution reaction catalyst is fabricated. This decoupled geometry enables the physical protection of the perovskite layer from the electrolyte, thus allowing excellent stability for over 100 h. To investigate the overall water splitting performance, this perovskite photocathode is connected in parallel with spin-filtering layer adopted photoanode based on chirality-induced spin selectivity. An unbiased solar water splitting was achieved using all the OIHP photoelectrodes, resulting in a remarkable unassisted solar-to-hydrogen efficiency of ~12% and a continuous 10 h stable operation.
Photocatalytic TiO2 Nanotube Layers on 3D Substrates Using Bipolar Electrochemistry
Authors: Sopha Hanna , Sepúlveda Sepúlveda Lina Marcela , Macak Jan M.
Published: February 2024

Self-organized TiO2 nanotube (TNT) layers have attracted considerable scientific and technological interest over the past almost 20 years, due to their wide range of applications, including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of these TNT layers is usually carried out by electrochemical anodization of valve Ti metal substrates in various F--containing electrolytes using a conventional 2-electrode set-up with the Ti substrate as anode and a Pt-foil as cathode.

By now, the TiO2 nanotube layer modification of Ti substrates is mainly focused on planar substrates, such as Ti foils and 2D Ti meshes, as these substrates can easily be connected to the potentiostat during anodization. However, for the real application in photocatalytic cleaners, 3D Ti substrates, such as 3D meshes or Ti spheres, are of high interest due to their significantly increased surface area compressed in a small volume.

To anodize such 3D Ti substrates towards TiO2 nanotube layers, bipolar electrochemistry can be employed instead of using a conventional set-up [3-5]. In such a bipolar set-up, the Ti substrate is not directly connected to the potentiostat but placed in an electrolyte between two so-called feeder electrodes. Due to the electric field between the feeder electrodes, the Ti substrate is polarized and can be anodized if the applied potential between the feeder electrodes is high enough. This method opens the door for the preparation of TNT layers with gradients in dimensions (i.e. diameter and length of the nanotubes) [3-5] as well as for the preparation of TNT layers on Ti substrates, which cannot be directly connected to the potentiostat, e.g. small Ti spheres [6] and complicated 3D printed structures [7].

In this presentation, the preparation of TNT layers on small Ti spheres [6] as well as on 3D printed Ti substrates [7] using bipolar electrochemistry will be shown. Their application in liquid and gas phase photocatalysis will be discussed. Furthermore, we will also show the possibility of using closed bipolar electrochemical cells, consisting of two closed half-cells with the Ti substrate as obstacle between the cells for the preparation of TiO2 nanotube layers with different dimensions on the two sides of a classical Ti foil [8].

References:

[1] J.M. Macak et al., Curr. Opin. Solid State Mater.
2007, 11, 3.

[2] Lee, K. et al., Chem. Rev.
2014, 114, 9385.

[3] G. Loget et al, J. Mater. Chem A
2014, 2, 17740.

[4] G. Loget et al., Langmuir
2014, 30, 15356.

[5] W. Wei et al., Electrochim. Acta
2015, 176, 1393.

[6] H. Sopha et al., Electrochem. Commun.
2020, 111, 106669.

[7] H. Sopha et al., Nano Lett.
2021, 21, 8701.

[8] H. Sopha et al., ChemElectroChem
2021, 8, 3827.
Catalytic Activity of Au-Cu Alloy on TiO2 Nanotubes for Alcohol Oxidation
Authors: Lipinska Wiktoria , Grochowska Katarzyna , Karczewski Jakub , Coy Emerson , Siuzdak Katarzyna
Published: February 2024

First fuel cell was discovered 180 years ago and still the ideal, namely cheap and effective catalytic materials are highly required. Such device allows to convert chemical energy into electrical one without pollutant gasses emission. In the case of alcohol fuel cells, methanol, ethanol, ethylene glycol and glycerine are considered as a power source. Platinum is commonly used for alcohol electrocatalyst, because of its high activity and stability. However, due to the high cost and limited supply platinum should be replaced by material that small amount is enough to reach satisfactory catalytic effect. In our work, we present the activity of gold-copper modified titania nanotubes toward electrocatalytic alcohol oxidation [1].

The material is fabricated using three steps such as: 1) anodization of Ti plate, 2) thin 10 nm AuCu alloy layer magnetron sputtering, and 3) rapid thermal annealing in an argon atmosphere [2]. Scanning electron microscopy confirmed the presence of well-ordered TiO2 nanotubes (TiNT) with diameter of 101 ± 13 nm and length of 709± 53 nm. After AuCu alloy magnetron sputtering and thermal treatment spherical nanoparticles were formed on NT surface. Based on top view SEM images the diameter of gold copper nanoparticles is equal to 38 ± 5 nm. However, the TEM images showed that diameter of nanoparticles changes from 5 nm to 60 nm (Figure 1a-d) where the bigger particles are on the top of the nanotubes. Applied fabrication procedure allowed us to obtain electrode material that can be used in methanol, ethylene glycol or glycerine oxidation. The highest catalytic activity of AuCu alloy was obtained for glycerine oxidation. Prepared material exhibited 90 times higher current density after glycerine addition to the alkaline solution than pure TiNT (Figure 1e). Furthermore, higher current density towards alcohol oxidation was registered for thermally annealed sample (an-AuCu/TiNT) than for non-annealed one (n-AuCu/TiNT).

Cyclic voltammetry measurements for the an-AuCu/TiNT in glycerine solution at different scan rates confirmed diffusion controlled process. The oxidation peak current density located at +0.3 V and +1 V grows up to 120 mV/s with slope of 51 and 81 µA/cm2 respectively, which confirmed more privilege process at +1 V vs. Ag/AgCl/0.1M KCl. We believe that the information reported in our work provide wider knowledge about new and more efficient electrodes for alcohol oxidation.

Research is financed by National Science Centre (Poland): Grant No. 2019/35/N/ST5/02604

[1] W. Lipińska et al. Journal of Materials Science, 57 (2022) 13345, DOI:10.1007/s10853-022-07471-7

[2] W. Lipińska et al. ACS Applied Materials & Interfaces, 13 (2021) 52967, DOI:10.1021/acsami.1c16271

Figure 1
Development of Durable Large-Sized CO2 Electrolysis Cells for Industrial Applications
Authors: Fujiwara Naoya , Kofuji Yusuke , Mikoshiba Satoshi , Kitagawa Ryota , Matsunaga Atsushi , Kikuchi Isamu , Shimotori Soichiro
Published: February 2024

Utilization of carbon dioxide (CO2) as a feedstock of valuable chemicals is necessary to achieve carbon neutrality. Toshiba is developing the low-temperature zero-gap type CO2 electrolysis cells to produce carbon monoxide (CO) [1,2]. CO can further be converted into various chemicals and fuels by catalytic reactions with hydrogen. To make the CO2 electrolysis technology industrially feasible, it is necessary to establish high-throughput system by expanding the electrode area and stacking the cells. Large-sized cells and stacks often suffer from low Faradaic efficiency for the CO production, which is related to insufficient and nonuniform supply of reactant CO2 gas to the cathode reaction sites. This time we focused on the development of large-sized single cells and fabricated an electrolysis cell with 400 cm2 electrodes. With properly designed gas flow plates and gaskets, the cell voltage and the CO Faradaic efficiency of the fabricated cell at a current density of 400 mA cm-2 were comparable to those of the previously developed smaller cells with 4 cm2 electrodes. The CO concentration in the cathode outlet gas reached ca. 80% by controlling the inlet CO2 flow rate. Stability is another essential property of CO2 electrolysis cells required for the industrial application. Cathode flooding and salt precipitation are major stability issues characteristic of relatively short-term operations, whose detailed mechanism is still in debate [3]. To mitigate those stability issues, we focused on the cathode inlet humidity and the pressure difference between the cathode and the anode. The former is related to the salt concentration in electrolyte solution around the cathode reaction sites, and the latter is related to the convection of electrolyte from the anode side to the cathode side. By controlling those parameters, stable performance over 100 h was achieved.

Part of this work was commissioned by Ministry of the Environment, Government of Japan.

[1] Y. Kofuji, A. Ono, Y. Sugano, A. Motoshige, Y. Kudo, M. Yamagiwa, J. Tamura, S. Mikoshiba, and R. Kitagawa, Chem. Lett., 50, 482-484 (2021).

[2] Y. Kiyota, Y. Kofuji, A. Ono, S. Mikoshiba, and R. Kitagawa, 242nd ECS Meeting, I05-1942 (2022).

[3] M. Sassenburg, M. Kelly, S. Subramanian, W. A. Smith, and T. Burdyny, ACS Energy Lett., 8, 321-331 (2023).
(Invited) Computational Predictions of Site-Dependent Reactivities for Complex Reactions in Confinement
Authors: Malviya Shubham , Bai Peng
Published: February 2024

It is well known that the relatively high overpotentials for oxygen evolution reactions arise from similar binding energies for HO* and HOO* intermediates that tend to move in lockstep on different catalysts. A strategy to break this scaling limitation is through differential stabilization of the two intermediates by engineering the reaction environment. Nanoporous materials such as zeolites and metal-organic frameworks provide such a possibility through their well-defined pore space that presents microscopically tunable reaction environments. Yet the predictive understanding of catalytic actions in these heterogeneous catalysts requires the ability to describe not only the electronic structure at the active site, but also how the extended environment interacts with the reacting species through individually weak yet collectively significant non-covalent interactions. In this talk, we present a new computational procedure that couples quantum-chemical methods and forcefield-based sampling to enable a consistent calculation of local activation energies for articulated reactants. As a first application, we studied hydrocarbon reactions in four different zeolites and showed how the method allows for the estimation of transition-state entropy and for the systematic calculation of site-dependent activation energies. The latter can be used to derive rigorous ensemble-averaged barriers for comparison with experiments, as well as guiding future strategies for controlling Al distributions during zeolite synthesis.
(Invited) Operando Optical Spectroscopy Analyses of Photoelectrochemical Water Oxidation Kinetics
Authors: Durrant James
Published: February 2024

Water oxidation is a key kinetic bottleneck in many photoelectrochemical systems for solar to fuels and chemicals. We have recently been developing an operando optical spectroscopic analysis to assay these reaction kinetics in metal oxide photoanodes. This technique, which we refer to as photoinduced absorption spectroscopy, is based around measuring the optical absorption of oxidising species (‘surface holes’) generated in photoanodes under anodic bias and pulsed (typically 5 s) light irradiation. These analyses have allowed us to observe a non-linear dependence of water oxidation kinetics on surface hole density, most typically a 3rd order rate law dependence under circa 1 sun irradiation conditions. In my talk I will talk about three different applications of this PIAS approach to investigate the function of BiVO4, Fe2O3 and TiO2 photoanodes. Firstly I will discuss how this non-linear dependence can be exploited to determine the photoelectrochemically active surface area of photoanodes as function of metal oxide nanostructuring. I will then go on to demonstrate that, when normalised for matched surface hole densities, water oxidation kinetics measured in under light irradiation or in the dark at strong anodic bias are identical, and discuss how this conclusion can be exploited to quantify the photovoltage under irradiation. Finally I will discuss deviation from rate law behaviour observed under > 1 sun irradiation conditions, and its mechanistic origin.
(Invited) High Productivity Electrocatalytic Water Splitting Using Diverse Water Sources
Authors: Takanabe Kazuhiro
Published: February 2024

Water electrolysis is a commercially established process. However, significant cost reductions are desired for the large scale applications anticipated in the future. Electrolysis is typically performed under extreme pH conditions due to the high reaction rate of the electrocatalyst and low solution resistance. On the other hand, energy conversion using electricity generated from renewable energy requires a water splitting electrocatalyst that is versatile, safe, and durable. Recent water splitting research has focused on the development of catalyst materials and elucidation of their efficient action under non-extreme pH conditions. However, there are several problems associated with water splitting in the mild pH range. The first problem is the lack of protons and hydroxide ions at mild pH, which leads to large concentration overpotentials. To solve these problems, concentrated buffered electrolytes are used to suppress local pH shifts and to compensate for the steady-state proton or hydroxyide ion. To maximize the buffering effect, concentrated buffer electrolyte solutions should be applied near the pKa values where protonated and deprotonated species coexist. A second problem at near-neutral pH levels is the inherently lower conductivity of the electrolyte solution compared to strongly acidic or strongly alkaline solutions. The ohmic potential (iR) drop between the anode and cathode is critical to the cell voltage of water splitting devices, especially at the high current densities that are industrially important. The conductivity at pH 7.0 of phosphate buffer can be maximized by varying the molar ratio and selecting the appropriate counter cation (K among Li, Na, K, and Cs). The choice of conditions essentially reduces viscosity and maximizes solubility, which strongly affects the conductivity of the solution. The conductivity of saturated K phosphate reaches a maximum of ~20 S m−1, but this value is still not as high as the alkaline one (~130 S m−1). Viscosity and solution resistance can be adjusted by mixing different electrolytes and fine-tuning the position of pKa within the target pH range. In water containing Mg2+ and Ca2+, precipitation of these ionic salts can be a problem. Keeping the pH between 8 and 10 prevents such precipitation. We are also attempting to intentionally use chloride ions, which have the highest concentration anion in seawater. In this way, solution resistance is further improved. Thus, it is emphasized that electrolyte engineering is an important technology for cost-effective water electrolysis by finding new reaction environments to efficiently electrolyze water under more moderate conditions.
(Invited) Long Term Operation of Photoelectrochemical Devices: Experiments and Modeling
Authors: Haussener Sophia
Published: February 2024

Achieving long term operation while maintaining a high energy conversion efficiency and large production rates is one of the main challenges for enhancing the economic competitiveness of solar fuel producing photoelectrochemical devices [1]. I will discuss computational and experimental methods to characterize the degradation of photoelectrochemical devices. The models consider multi-scale approaches and multi-physics phenomena [2]. This is required in order to properly account for all the competing and convoluting effects and to properly extract and quantify the degradation from experimental data. I will present our experimental setup that consists of a multi-PEC cell array in order to obtain sufficient and statistically representative data. Additional experiments under high-flux solar irradiation conditions are presented that allow – in conjunction with the model – for the extraction of degradation characteristics and the development of accelerated age testing procedures. I will also report on the long term operation of our outdoor photo-electrochemical system demonstration operating under concentrated light [3].

[1] M. Dumortier, S. Tembhurne, S. Haussener, Energy Environmental Science, 8: 3614-3628, 2015.

[2] F. Nandjou, S. Haussener, ACS Applied Materials & Interfaces. 10.1021/acsami.2c08204, 2022.

[3] I. Holmes-Gentle, S. Tembhurne, C. Suter, S. Haussener, Nature Energy, 10.1038/s41560-023-01247-2, 2023.
The Localized Surface Plasmon Resonances (LSPR) Origin of W18O49 and Application in Photocatalysis
Authors: Zhaoyu Ma , Zhang Junying
Published: February 2024

A key solution for high-efficiency solar-to-fuel conversion is to fabricate semiconductor photocatalysts with ultra-broad spectral absorption and high charge-carriers utilization efficiency [1]. The localized surface plasmon resonances (LSPR) effect of W18O49 induces visible and near-infrared (NIR) light absorption efficiently, realizing full-spectrum solar-light driven photocatalysis [2]. Therefore, it is meaningful to study the LSPR origin and seek ways to make full use of photo-induced hot electron of W18O49. In our work, by density-functional theory calculation, the LSPR has been proposed to originate from the localized electron confinement around lattice W5+–W5+ pairs in the unique structure of W18O49, which explains the experimental results that W18O49 has a broad absorption ranging from visible to NIR region, independent of the particle shape and size. Hierarchical-structured W18O49 microflowers with high absorbance have been coated with ZnIn2S4 nanosheets to achieve cocatalyst-free photocatalytic composite, which exhibits outstanding H2 production of 902.57 µmol within 3 h under simulated solar-light. [3] Z-scheme photocatalytic heterojunction of W18O49 microflowers and g-C3N4 nanosheets has been constructed through electrostatic self-assembly method, which shows higher photocatalytic hydrogen production performance than the counterpart synthesized by hydrothermal method. [4]

Reference

[1] Q. Wang, K. Domen, Chem. Rev. 2020, 120, 919−985.

[2] Z. Y. Zhang, J. D. Huang, Y. R. Fang, et al., Adv. Mater. 2017, 29, 1606688.

[3] Y. Lu, X.F. Jia, Z.Y. Ma, et al., Adv. Funct. Mater., 2022, 32, 2203638.

[4] Z. Y. Ma, W. P. Li, X. F. Jia, et al., Mater. Today. Adv. 2022, 15, 100249.
(Invited) Plasmonic Aerogels for Gas-Phase Photocatalytic Reactions
Authors: Zhi Mingjia
Published: February 2024

As a special form of material, aerogel has emerged as a promising type of photocatalyst. Owing to the large specific surface area and the developed pore texture, it would be suitable to drive various gas-phase reactions such as CO2 reduction and CH4 conversion. More importantly, the size of the fundamental building blocks in an aerogel, which is typically 5-20 nm, is approaching that of the noble metals with the surface plasmon resonance (SPR) effect. Innovated by Rolison and Niederberger(1, 2), aerogels with plasmonic effect have been extensively studied as photocatalysts for hydrogen evolution and dye degradation in liquid medium

This talk then aims to introduce some of our recent results on the construction and evaluation of plasmonic noble metal/ceria composite aerogels, which cover the content from the synthesis to new applications. Modified synthesis methods are developed for the rational incorporation of plasmonic metal nanoparticles such as Ag and Au into an aerogel backbone in one step, which offers an alternative route to tune the composition and size of these nanoparticles, or even building single-atom composite aerogels in the conventional sol-gel methodology(3). When these plasmonic aerogel photocatalysts are applied for gas-phase CO2 reduction and non-oxidative CH4 coupling reaction, good performance is observed. The synergistic effect of plasmonic sensitizer and co-catalyst is discussed and is responsible for the performance enhancement.

P. A. DeSario, J. J. Pietron, A. Dunkelberger, T. H. Brintlinger, O. Baturina, R. M. Stroud, J. C. Owrutsky and D. R. Rolison, Langmuir, 33, 9444 (2017).

F. Rechberger and M. Niederberger, Nanoscale Horizons, 2, 6 (2017).

M. Wu, C. Ouyang, Z. Ye, S. Li, Z. Hong and M. Zhi, ACS Applied Energy Materials, 5, 7335 (2022).
Layered Nanocomposites of Polymer-Functionalized Reduced Graphene Oxide and Borocarbonitride with MoS2 and MoSe2 and Their Hydrogen Evolution Reaction Activity
Authors: Servottam Swaraj , Rao Chintamani Nagesa Ramachandra
Published: February 2024

Two dimensional heterostructure have been widely investigated for various applications in electrochemistry such as water splitting and battery storage. These heterostructures are mainly formed due to vander waals interaction, covalent cross-linking and electrostatic interactions. Herein, we have prepared nanocomposite of positively charged poly (diallyldimethylammonium chloride) (PDDA, shown as P)-functionalized reduced graphene oxide (RGO) and borocarbonitride (BC6N, shown as BCN for simplicity) sheets with layers of negatively charged MoS2 and MoSe2 by electrostatic interaction in solution phase. The nanocomposites exhibit superior photocatalytic hydrogen evolution reaction (HER) activity compared to the individual components, and the value increases with the MoS2/MoSe2 content. The highest photocatalytic HER activity obtained is 11230 μmol h–1 g–1 in the nanocomposite P.RGO-MoS2, with a P.RGO-MoS2 ratio of 1:5. The P.RGO-MoSe2 (1:5) and P.BCN-MoS2 (1:5) nanocomposites exhibit somewhat lower activities of 9540 and 8593 μmol h–1 g–1, respectively. Prompted by literature reports that carbon-rich BCNs are efficient HER electrocatalysts, we have examined the electrocatalytic HER activity of P.BCN-MoS2 (1:1, 1:5, and 1:7) nanocomposites. The electrocatalytic HER activity of P.BCN-MoS2 (1:5) is found to be extraordinary, with an onset potential of −50 mV (vs RHE), comparable to that of platinum.

References: -

Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 2013 499:7459
499, 419–425 (2013).

Pramoda, K., Gupta, U., Ahmad, I., Kumar, R. & Rao, C. N. R. Assemblies of covalently cross-linked nanosheets of MoS2 and of MoS2–RGO: synthesis and novel properties. J Mater Chem A Mater
4, 8989–8994 (2016).

Pramoda, K., Servottam, S., Kaur, M. & Rao, C. N. R. Layered Nanocomposites of Polymer-Functionalized Reduced Graphene Oxide and Borocarbonitride with MoS2 and MoSe2 and Their Hydrogen Evolution Reaction Activity. ACS Appl Nano Mater
3, 1792–1799 (2020).

Figure 1
(Invited) Dye-Sensitized Molecular Photoelectrodes for CO2 Reduction Using Water as a Reductant
Authors: Ishitani Osamu
Published: February 2024

Photocatalytic CO2 reduction using visible light and water as a reductant has been one of the important targets for solving global warming problem and shortage of energy and carbon resources. In this presentation, I talk about two projects, i.e., (1) supramolecular photocatalysts with both functions as photosensitizer and catalysts and (2) photocatalytic CO2 reduction coupled to water oxidation.

(1) Highly efficient supramolecular photocatalysts for CO2 reduction1-3

Since CO2 is the most oxidized state of carbon, one-electron reduction of CO2 is an extraordinarily high endergonic reaction. From the viewpoints of low-energy light application, the multi-electron reduction of CO2 via chemical reactions promises to be a more valuable process. This is a main reason why both a photosensitizer and a catalyst are required to promote efficient photocatalytic CO2 reduction. We have developed so-called supramolecular photocatalyts that have both the photosensitizer and the catalyst units. This bonding in the supramolecular photocatalysts can accelerate electron transfer between the two units, which improves the performance of the photocatalytic system, especially on the surface of photofunctional solid materials as described below.

(2) Molecular photoelectrodes for photocatalytic CO2 reduction with water as a reductant 1,4

The molecular photocatalytic systems have a weakness, i.e., weak oxidation power in the excited state. For practical application, water should be used as an electron donor. For overcoming this problem, we have developed a hybrid system consisting of the supramolecular photocatalyst and semiconductor electrodes. The hybrid photoelectrochemical cell consisting of this hybrid photocathode and n-type semiconductor photoanode induced visible-light-driven CO2 reduction with water as a reductant to generate CO and O2.

References

“Photocatalytic Systems for CO2 Reduction: Metal-Complex Photocatalysts and Their Hybrids with Photofunctional Solid Materials” Kumagai, H.; Tamaki, Y.; Ishitani, O., Acc. Chem. Res.
2022,
55, 978-990.

“Mechanistic study of photocatalytic CO2 reduction using a Ru(II)-Re(I) supramolecular photocatalyst” Kamogawa, K.; Shimoda, Y.; Miyata, K.; Onda, K.; Yamazaki, Y.; Tamaki, Y.; Ishitani, O., Chem. Sci.
2021,
12, 9682-9693.

“Supramolecular Photocatalysts for the Reduction of CO2” Tamaki, Y.; Ishitani, O., ACS Cat.
2017,
7, 3394-3409.

“Supramolecular photocatalysts fixed on the inside of the polypyrrole layer in dye sensitized molecular photocathodes: application to photocatalytic CO2 reduction coupled with water oxidation. Kuttassery, F.; Kumagai, H.; Kamata, R.; Ebato, Y.; Higashi, M.; Suzuki, H.; Abe, R.; Ishitani, O., Chem. Sci.
2021,
12, 13216-13232.

Figure 1