A Dinuclear Ruthenium‐Based Water Oxidation Catalyst: Use of Non‐Innocent Ligand Frameworks for Promoting Multi‐Electron Reactions

Insight into how H₂O is oxidized to O₂ is envisioned to facilitate the rational design of artificial water oxidation catalysts, which is a vital component in solar‐to‐fuel conversion schemes. Herein, we report on the mechanistic features associated with a dinuclear Ru‐based water oxidation catalyst. The catalytic action of the designed Ru complex was studied by the combined use of high‐resolution mass spectrometry, electrochemistry, and quantum chemical calculations. Based on the obtained results, it is suggested that the designed ligand scaffold in Ru complex 1 has a non‐innocent behavior, in which metal–ligand cooperation is an important part during the four‐electron oxidation of H₂O. This feature is vital for the observed catalytic efficiency and highlights that the preparation of catalysts housing non‐innocent molecular frameworks could be a general strategy for accessing efficient catalysts for activation of H₂O.     

A Si Photocathode Protected and Activated with a Ti and Ni Composite Film for Solar Hydrogen Production

An efficient, stable and scalable hybrid photoelectrode for visible‐light‐driven H₂ generation in an aqueous pH 9.2 electrolyte solution is reported. The photocathode consists of a p‐type Si substrate layered with a Ti and Ni‐containing composite film, which acts as both a protection and electrocatalyst layer on the Si substrate. The film is prepared by the simple drop casting of the molecular single‐source precursor, [{Ti₂(OEt)₉(NiCl)}₂] (TiNi_pre), onto the p‐Si surface at room temperature, followed by cathodic in situ activation to form the catalytically active TiNi film (TiNi_cat). The p‐Si|TiNi_cat photocathode exhibits prolonged hydrogen generation with a stable photocurrent of approximately ?5 mA cm^?2 at 0 V vs. RHE in an aqueous pH 9.2 borate solution for several hours, and serves as a benchmark non‐noble photocathode for solar H₂ evolution that operates efficiently under neutral–alkaline conditions.     

Alloyed ZnS–CuInS2 Semiconductor Nanorods and Their Nanoscale Heterostructures for Visible‐Light‐Driven Photocatalytic Hydrogen Generation

A promising photocatalytic system in the form of heterostructured nanocrystals (HNCs) is presented wherein alloyed ZnS–CuInS₂ (ZCIS) semiconductor nanorods are decorated with Pt and Pd₄S nanoparticles. This is apparently the first report on the colloidal preparation and photocatalytic behavior of ZCIS–Pt and ZCIS–Pd₄S nanoscale heterostructures. Incorporation of Pt and Pd₄S cocatalysts leads to considerable enhancement of the photocatalytic activity of ZCIS for visible‐light‐driven hydrogen production.     

A Flexible Electrode Based on Iron Phosphide Nanotubes for Overall Water Splitting

The design of cheap and efficient water splitting systems for sustainable hydrogen production has attracted increasing attention. A flexible electrode, based on carbon cloth substrate and iron phosphide nanotubes coated with an iron oxide/phosphate layer, is shown to catalyze overall water splitting. The as‐prepared flexible electrode demonstrates remarkable electrocatalytic activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at modest overpotentials. The surface iron oxide/phosphate, which is formed in situ, is proposed to improve the HER activity by facilitating the water‐dissociation step and serves directly as the catalytically‐active component for the OER process.     

Chemical Vapor Deposition of FeOCl Nanosheet Arrays and Their Conversion to Porous α‐Fe2O3 Photoanodes for Photoelectrochemical Water Splitting

FeOCl nanosheet arrays were deposited on fluorine‐doped tin oxide glass substrates through a chemical vapor deposition method and further converted to hematite porous nanosheet arrays. A much enhanced photocurrent was obtained for such hematite films, which was three times higher than that of a planar hematite film at 1.23 V versus a reversible hydrogen reference electrode.     

CNT/β-AgVO_3混杂材料的制备及其光催化分解水析氧性能

采用水热法合成出单斜结构的β-AgVO3纳米棒和CNT/β-AgVO3光催化剂,在可见光模拟系统中以碘酸钾为电子捕获剂,检测氧气生成速率表征催化剂的光催化性能,并借助X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)、紫外-可见光漫反射吸收光谱(UV-Vis)等对催化剂粉体进行了表征。实验结果表明,CNT附着在β-AgVO3颗粒表面有利于光生电子的转移和光解水析氧反应。CNT/β-AgVO3催化剂较之纯β-AgVO3催化剂活性显著提高。当CNT附着量为1.5%时,析氧速率可稳定在250μmol·g-1·h-1。     

Resolving the Differences Between the 1.9 Å and 1.95 Å Crystal Structures of Photosystem II: A Single Proton Relocation Defines Two Tautomeric Forms of the Water‐Oxidizing Complex

Great progress has been made in characterizing the water‐oxidizing complex (WOC) in photosystem II (PSII) with the publication of a 1.9 Å resolution X‐ray diffraction (XRD) and recently a 1.95 Å X‐ray free‐electron laser (XFEL) structure. However, these achievements are under threat because of perceived conflicts with other experimental data. For the earlier 1.9 Å structure, lack of agreement with extended X‐ray absorption fine structure (EXAFS) data led to the notion that the WOC suffered from X‐ray photoreduction. In the recent 1.95 Å structure, Mn photoreduction is not an issue, but poor agreement with computational models which adopt the ‘high’ oxidation state paradigm, has again resulted in criticism of the structure on the basis of contamination with lower S states of the WOC. Here we use DFT modeling to show that the distinct WOC geometries in the 1.9 and 1.95 Å structures can be straightforwardly accounted for when the Mn oxidation states are consistent with the ‘low’ oxidation state paradigm. Remarkably, our calculations show that the two structures are tautomers, related by a single proton relocation.     

The Interaction of Water with Free Mn4O4+ Clusters: Deprotonation and Adsorption‐Induced Structural Transformations

As the biological activation and oxidation of water takes place at an inorganic cluster of the stoichiometry CaMn₄O₅, manganese oxide is one of the materials of choice in the quest for versatile, earth‐abundant water splitting catalysts. To probe basic concepts and aid the design of artificial water‐splitting molecular catalysts, a hierarchical modeling strategy was employed that explores clusters of increasing complexity, starting from the tetramanganese oxide cluster Mn₄O₄⁺ as a molecular model system for catalyzed water activation. First‐principles calculations in conjunction with IR spectroscopy provide fundamental insight into the interaction of water with Mn₄O₄⁺, one water molecule at a time. All of the investigated complexes Mn₄O₄(H₂O)_n⁺ (n=1–7) contain deprotonated water with a maximum of four dissociatively bound water molecules, and they exhibit structural fluxionality upon water adsorption, inducing dimensional and structural transformations of the cluster core.     

Chemical‐Bath‐Deposited Indium Oxide Microcubes for Solar Water Splitting

We fabricated films of cubic indium oxide (In₂O₃) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X‐ray diffraction analysis, Raman scattering, X‐ray photoelectron spectroscopy, and scanning electron microscopy, and the three‐dimensional microstructure of the In₂O₃ cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In₂O₃ microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm^?2. Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm^?2.