Pt Single Atoms on CrN Nanoparticles Deliver Outstanding Activity and CO Tolerance in the Hydrogen Oxidation Reaction

The large-scale application of proton exchange membrane fuel cells is currently hampered by high cost of commercial Pt catalysts and their susceptibility to poisoning by CO impurities in H₂ feed. In this context, the development of CO-tolerant electrocatalysts with high Pt atom utilization efficiency for hydrogen oxidation reaction (HOR) is of critical importance. Herein, Pt single atoms are successfully immobilized on chromium nitride nanoparticles by atomic layer deposition method, denoted as Pt SACs/CrN. Electrochemical tests establish Pt SACs/CrN to be a very efficient HOR catalyst, with a mass activity that is 5.7 times higher than commercial PtRu/C. Strikingly, the excellent performance of Pt SACs/CrN is maintained after introducing 1000 ppm of CO in H₂ feed. The excellent CO-tolerance of Pt SACs/CrN is related to weaker CO adsorption on Pt single atoms. This work provides guidelines for the design and construction of active and CO-tolerant catalysts for HOR.     

Interfacing Photosynthetic Membrane Protein with Mesoporous WO3 Photoelectrode for Solar Water Oxidation

Photosynthetic biocatalysts are emerging as a new class of materials, with their sophisticated and intricate structure, which promise improved remarkable quantum efficiency compared to conventional inorganic materials in artificial photosynthesis. To break the limitation of efficiency, the construction of bioconjugated photo‐electrochemical conversion devices has garnered substantial interest and stood at the frontier of the multidisciplinary research between biology and chemistry. Herein, a biohybrid photoanode of a photosynthetic membrane protein (Photosystem II (PS II)), extracted from fresh spinach entrapped on mesoporous WO₃ film, is fabricated on fluorine‐doped tin oxide. The PS II membrane proteins are observed to communicate with the WO₃ electrode in the absence of any soluble redox mediators and sacrificial reagents under the visible light of the solar spectrum, even to 700 nm. The biohybrid electrode undergoes electron transfer and generates a significantly enhanced photocurrent compared to previously reported PS II‐based photoanodes with carbon nanostructures or other semiconductor substrates for solar water oxidation. The maximum incident photon‐to‐current conversion efficiency reaches 15.24% at 400 nm in the visible light region. This work provides some insights and possibilities into the efficient assembly of a future solar energy conversion system based on visible‐light‐responsive semiconductors and photosynthetic proteins.     

Shape‐Dependent Activity of Ceria for Hydrogen Electro‐Oxidation in Reduced‐Temperature Solid Oxide Fuel Cells

Single crystalline ceria nanooctahedra, nanocubes, and nanorods are hydrothermally synthesized, colloidally impregnated into the porous La_0.9Sr_0.1Ga_0.8Mg_0.2O_3‐δ (LSGM) scaffolds, and electrochemically evaluated as the anode catalysts for reduced temperature solid oxide fuel cells (SOFCs). Well‐defined surface terminations are confirmed by the high‐resolution transmission electron microscopy — (111) for nanooctahedra, (100) for nanocubes, and both (110) and (100) for nanorods. Temperature‐programmed reduction in H₂ shows the highest reducibility for nanorods, followed sequentially by nanocubes and nanooctahedra. Measurements of the anode polarization resistances and the fuel cell power densities reveal different orders of activity of ceria nanocrystals at high and low temperatures for hydrogen electro‐oxidation, i.e., nanorods > nanocubes > nanooctahedra at T ≤ 450 °C and nanooctahedra > nanorods > nanocubes at T ≥ 500 °C. Such shape‐dependent activities of these ceria nanocrystals have been correlated to their difference in the local structure distortions and thus in the reducibility. These findings will open up a new strategy for design of advanced catalysts for reduced‐temperature SOFCs by elaborately engineering the shape of nanocrystals and thus selectively exposing the crystal facets.     

Electronic Structure Engineering of Pt Species over Pt/WO3 toward Highly Efficient Electrocatalytic Hydrogen Evolution

Pt-based supported materials, a widely used electrocatalyst for hydrogen evolution reaction (HER), often experience unavoidable electron loss, resulting in a mismatching of electronic structure and HER behavior. Here, a Pt/WO₃ catalyst consisting of Pt species strongly coupled with defective WO₃ polycrystalline nanorods is rationally designed. The electronic structure engineering of Pt sites on WO₃ can be systematically regulated, and so that the optimal electron-rich Pt sites on Pt/WO₃-600 present an excellent HER activity with only 8 mV overpotential at 10 mA cm⁻². Particularly, the mass activity reaches 7015 mA mg⁻¹ at the overpotential of 50 mV, up to 26-fold higher than that of the commercial Pt/C. The combination of experimental and theoretical results demonstrates that the O vacancies of WO₃ effectively mitigate the tendency of electron transfer from Pt sites to WO₃, so that the d-band center could reach an appropriate level relative to Fermi level, endowing it with a suitable $\Delta G_{{\mathrm{H}}^{\ast }}$. This work identifies the influence of the electronic structure on catalytic activity.     

Interstitial Hydrogen Atom to Boost Intrinsic Catalytic Activity of Tungsten Oxide for Hydrogen Evolution Reaction

Tungsten oxide (WO₃) is an appealing electrocatalyst for the hydrogen evolution reaction (HER) owing to its cost-effectiveness and structural adjustability. However, the WO₃ electrocatalyst displays undesirable intrinsic activity for the HER, which originates from the strong hydrogen adsorption energy. Herein, for effective defect engineering, a hydrogen atom inserted into the interstitial lattice site of tungsten oxide (H_0.23WO₃) is proposed to enhance the catalytic activity by adjusting the surface electronic structure and weakening the hydrogen adsorption energy. Experimentally, the H_0.23WO₃ electrocatalyst is successfully prepared on reduced graphene oxide. It exhibits significantly improved electrocatalytic activity for HER, with a low overpotential of 33 mV to drive a current density of 10 mA cm⁻² and ultra-long catalytic stability at high-throughput hydrogen output (200 000 s, 90 mA cm⁻²) in acidic media. Theoretically, density functional theory calculations indicate that strong interactions between interstitial hydrogen and lattice oxygen lower the electron density distributions of the d-orbitals of the active tungsten (W) centers to weaken the adsorption of hydrogen intermediates on W-sites, thereby sufficiently promoting fast desorption from the catalyst surface. This work enriches defect engineering to modulate the electron structure and provides a new pathway for the rational design of efficient catalysts for HER.     

Synergetic Structural Transformation of Pt Electrocatalyst into Advanced 3D Architectures for Hydrogen Fuel Cells

A new direction for developing electrocatalysts for hydrogen fuel cell systems has emerged, based on the fabrication of 3D architectures. These new architectures include extended Pt surface building blocks, the strategic use of void spaces, and deliberate network connectivity along with tortuosity, as design components. Various strategies for synthesis now enable the functional and structural engineering of these electrocatalysts with appropriate electronic, ionic, and electrochemical features. The new architectures provide efficient mass transport and large electrochemically active areas. To date, although there are few examples of fully functioning hydrogen fuel cell devices, these 3D electrocatalysts have the potential to achieve optimal cell performance and durability, exceeding conventional Pt powder (i.e., Pt/C) electrocatalysts. This progress report highlights the various 3D architectures proposed for Pt electrocatalysts, advances made in the fabrication of these structures, and the remaining technical challenges. Attempts to develop design rules for 3D architectures and modeling, provide insights into their achievable and potential performance. Perspectives on future developments of new multiscale designs are also discussed along with future study directions.     

Kinetic-Modulated Crystal Phase of Ru for Hydrogen Oxidation

Crystal-phase-engineering provides a powerful strategy for regulating the catalytic performance yet remains great challenge. Herein, the kinetic-modulated crystal-phase-control of Ru nanosheet assemblies (Ru NAs) is demonstrated by simply altering the concentration of citric acid (CA). Detailed experimental results reveal that high concentration of CA retards the growth kinetics and thus leads to the formation of metastable face-centered cubic (fcc) Ru NAs, while low concentration of CA results in the fast growth kinetics and the preferential formation of Ru NAs with stable hexagonal close packed (hcp) phase. Moreover, Ru NAs with different phases are used as catalyst for hydrogen oxidation reaction (HOR) to evaluate the effects of crystal phase on catalytic performance. Impressively, Ru NAs with fcc phase display a mass activity of 2.75 A mg_Ru⁻¹ at 50 mV, which is much higher than those of Ru NAs with fcc/hcp (1.02 A mg_Ru⁻¹) and hcp (0.74 A mg_Ru⁻¹) phases. Theoretical calculations show that fcc Ru NAs display weaker adsorption toward ^*H and lower energy barrier toward the rate-determining step (RDS) during HOR. This work provides a facile strategy for regulating the crystal phase of Ru nanocrystals, which may attract rapid interests of researchers in materials, chemistry, and catalysis.     

Hydroxyl-Binding Energy-Induced Kinetic Gap Narrowing between Acidic and Alkaline Hydrogen Oxidation Reaction on Intermetallic Ru3Sn7 Catalyst

Developing highly efficient catalysts toward alkaline hydrogen oxidation reaction (HOR) and narrowing the kinetic gap between acidic and alkaline electrolytes are of great importance for the practical application of alkaline exchange membrane fuel cell . Herein, ordered Ru₃Sn₇/C intermetallic compound has been developed for the HOR under alkaline and acidic conditions. The authors demonstrate that the ordered intermetallic Ru₃Sn₇/C shows much enhanced HOR activity, stability, and CO-tolerance compared with its disordered RuSn solid solution alloy counterpart. More importantly, the authors find that the kinetic gap of HOR between acidic and alkaline media is significantly narrowed in the as-synthesized intermetallic Ru₃Sn₇/C catalysts. Combined experiment results and theoretical calculations, the authors understand that promoted hydroxyl-binding energy on Ru₃Sn₇/C derived from the intermetallic-induced strong electron interaction is responsible for the accelerated alkaline HOR performance and narrowed kinetic gap.     

Carbon-Doped Nickle Via a Fast Decarbonization Route for Enhanced Hydrogen Oxidation Reaction in Alkaline Media

Nickel (Ni) based materials with non-metal heteroatom doping are competitive substitutes for platinum group catalyst toward alkaline hydrogen oxidation reaction (HOR). However, the incorporation of non-metal atom into the lattice of conventional fcc phase Ni can easily trigger a structural phase transformation, forming hcp phase nonmetallic intermetallic compounds. Such tangle phenomenon makes it difficult to uncover the relationship between HOR catalytic activity and doping effect on fcc phase Ni. Herein, taking trace carbon doped Ni (C-Ni) nanoparticles as an example, a new nonmetal doped Ni nanoparticles synthesized by a simple fast decarbonization route using Ni₃C as precursor is presented, which provides an ideal platform to study the structure-activity relationship between alkaline HOR performance and non-metal doping effect toward fcc phase Ni. The obtained C-Ni exhibits an enhanced alkaline HOR catalytic activity compared with pure Ni, approaching to commercial Pt/C. X-ray absorption spectroscopy confirms that the trace carbon doping can modulate the electronic structure of conventional fcc phase nickel. Besides, theoretical calculations suggest that the introducing of C atoms can effectively regulate the d-band center of Ni atoms, resulting in the optimized hydrogen absorption, thereby improving the HOR activity.     

双氧水和退火温度对WO_3薄膜光电化学性质的影响

以WO3粉体合成的W络合离子作为前驱液,超声喷雾热裂解法（USP）制备出WO_3薄膜,研究前驱液中H_2O_2添加量、薄膜沉积温度和薄膜退火温度对WO_3薄膜光电化学性能的影响,利用XRD、UV-vis和光电流光谱（IPCE）等对薄膜进行表征,实验结果表明,USP制备的WO_3薄膜为单斜相且沿（200）晶面优势生长;前驱液中双氧水量的增加导致WO_3薄膜禁带宽度（E_g）增加;薄膜的平带电位（Vfb）在-0.27~-0.05V之间（vs.SCE,pH=7）,且掺杂浓度随退火温度升高而降低;在0.1M的Na_2SO_3溶液中,薄膜的IPCE随退火温度升高而降低,随H_2O_2量的减小IPCE增高。     

Engineering the Metal/Oxide Interface of Pd Nanowire@CuOx Electrocatalysts for Efficient Alcohol Oxidation Reaction

The development of new type electrocatalysts with promising activity and antipoisoning ability is of great importance for electrocatalysis on alcohol oxidation. In this work, Pd nanowire (PdNW)/CuO_x heterogeneous catalysts with different types of Pd? O? Cu interfaces (Pd/amorphous or crystalline CuO_x) are prepared via a two‐step hydrothermal strategy followed by an air plasma treatment. Their interface‐dependent performance on methanol and ethanol oxidation reaction (MOR and EOR) is clearly observed. The as‐prepared PdNW/crystalline CuO_x catalyst with 17.2 at% of Cu on the PdNW surface exhibits better MOR and EOR activity and stability, compared with that of PdNW/amorphous CuO_x and pristine PdNW catalysts. Significantly, both the cycling tests and the chronoamperometric measurements reveal that the PdNW/crystalline CuO_x catalyst yields excellent tolerance toward the possible intermediates including formaldehyde, formic acid, potassium carbonate, and carbon monoxide generated during the MOR process. The detailed analysis of their chemical state reveals that the enhanced activity and antipoison ability of the PdNW/crystalline CuO_x catalyst originates from the electron‐deficient Pd^δ+ active sites which gradually turn into Pd₅O₄ species during the MOR catalysis. The Pd₅O₄ species can likely be stabilized by moderate crystalline CuO_x decorated on the surface of PdNW due to the strong Pd? O? Cu interaction.     

水热合成镍铜复合磷化物及其电催化析氢与肼氧化性能

以镍网(NM, Nickel Mesh)为基体、NaH₂PO₂·H₂O为磷源、CuSO₄·5H₂O为铜源、NiSO₄·6H₂O为镍源, 采用一步水热法合成镍铜磷复合电催化剂, 对制备工艺进行优化, 并通过不同方法进行形貌、结构、组成和电催化性能表征。结果表明：当溶液中镍、铜、磷的配比为8: 1 :20时, 在140 ℃水热合成24 h, 制得主晶相为Ni₂P和Cu₃P、具有三级微纳结构的镍铜磷复合电催化剂。在电流密度为10 mA·cm ^-2时, NiCuP/NM的催化析氢及肼氧化过电势分别为165和49 mV; 在双电极体系中, 同电流密度下的分解槽压仅为0.750 V, 催化24 h后分解槽压几乎保持不变, 展现出优异的催化稳定性。无论三电极体系还是双电极体系均表现出优异的催化活性。分析认为, 电催化活性面积为空白镍网的近14倍, 为电催化过程提供了大量的活性位点; 掺入P改变了Ni、Cu原子的电子结构, 提高了材料的本征肼氧化活性, 两者的协同作用促进了电催化活性的提升。本研究为纳米尺度的合成提供了一个新的视角, 有望推动新型纳米孔结构材料在燃料电池和传感器应用中的发展。     

Prereduction of Metal Oxides via Carbon Plasma Treatment for Efficient and Stable Electrocatalytic Hydrogen Evolution

Prereduction of transition metal oxides is a feasible and efficient strategy to enhance their catalytic activity for hydrogen evolution. Unfortunately, the prereduction via the common H₂ annealing method is unstable for nanomaterials during the hydrogen evolution process. Here, using NiMoO₄ nanowire arrays as the example, it is demonstrated that carbon plasma (C‐plasma) treatment can greatly enhance both the catalytic activity and the long‐term stability of transition metal oxides for hydrogen evolution. The C‐plasma treatment has two functions at the same time: it induces partial surface reduction of the NiMoO₄ nanowire to form Ni₄Mo nanoclusters, and simultaneously deposits a thin graphitic carbon shell. As a result, the C‐plasma treated NiMoO₄ can maintain its array morphology, chemical composition, and catalytic activity during long‐term intermittent hydrogen evolution process. This work may pave a new way for simultaneous activation and stabilization of transition metal oxide‐based electrocatalysts.     

Coupling Hydrazine Oxidation with Seawater Electrolysis for Energy-Saving Hydrogen Production over Bifunctional CoNC Nanoarray Electrocatalysts

Seawater electrolysis is a promising method to produce H₂ without relying on scarce freshwater resource, but its high energy consumption and inevitable accompany of competitive chlorine oxidation reaction (ClOR) are still great technological challenges. Herein, a metal-organic framework (MOF)-templated pyrolysis strategy to prepare uniform cobalt/nitrogen-codoped carbon nanosheet arrays on carbon cloth (CC@CoNC) as highly-efficient but low-cost bifunctional electrocatalysts for hydrazine-assisted seawater electrolysis is explored. The optimized CoNC nanosheet arrays can be used as an efficient bifunctional electrocatalyst to catalyze hydrazine oxidation reaction and hydrogen evolution reaction, remarkably reducing the energy consumption and nicely overcome the undesired anodic corrosion problems caused by ClOR. Impressively, a hydrazine-assisted water electrolysis system is successfully assembled by using the optimized CC@CoNC as both cathode and anode, which only needs an ultra-low cell voltage of 0.557 V and an electricity consumption of 1.22 kW h per cubic meter of H₂ to achieve 200 mA cm⁻². Furthermore, the optimized CC@CoNC can also show greatly improved stability in the hydrazine-assisted seawater electrolysis system for H₂ production, which can work steadily for above 40 h at ≈10 mA cm⁻². This study may offer great opportunities for obtaining hydrogen energy from infinite ocean resource by an eco-friendly method.     

Self‐Templated Fabrication of MoNi4/MoO3‐x Nanorod Arrays with Dual Active Components for Highly Efficient Hydrogen Evolution

A binder‐free efficient MoNi₄/MoO_3‐x nanorod array electrode with 3D open structure is developed by using Ni foam as both scaffold and Ni source to form NiMoO₄ precursor, followed by subsequent annealing in a reduction atmosphere. It is discovered that the self‐templated conversion of NiMoO₄ into MoNi₄ nanocrystals and MoO_3‐x as dual active components dramatically boosts the hydrogen evolution reaction (HER) performance. Benefiting from high intrinsic activity, high electrochemical surface area, 3D open network, and improved electron transport, the resulting MoNi₄/MoO_3‐x electrode exhibits a remarkable HER activity with extremely low overpotentials of 17 mV at 10 mA cm^?2 and 114 mV at 500 mA cm^?2, as well as a superior durability in alkaline medium. The water–alkali electrolyzer using MoNi₄/MoO_3‐x as cathode achieves stable overall water splitting with a small cell voltage of 1.6 V at 30 mA cm ^{? 2}. These findings may inspire the exploration of cost‐effective and efficient electrodes by in situ integrating multiple highly active components on 3D platform with open conductive network for practical hydrogen production.     

P Doped MoO3−x Nanosheets as Efficient and Stable Electrocatalysts for Hydrogen Evolution

A P doped MoO_3?x nanocomposite material with rich oxygen vacancies is successfully fabricated by a two‐step intercalation method, which presents superior activity for the hydrogen evolution reaction with low overpotential and fast electron transfer. In 0.5 m H₂SO₄, it displays an overpotential of 166 mV for driving the current density of 10 mA cm^?2. Moreover, it also shows a good catalytic stability in the electrolytes with different pH, 0.5 m H₂SO₄ (strong acid), 0.5 m Na₂SO₄ (neutral solution), and 0.1 m NaOH (strong base). The superior catalytic activity and stability are due to to the synergistic effect between the P element doping and the oxygen vacancies.