Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm−2. The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

The use of water as an oxygen and hydrogen source for the paired oxygenation and hydrogenation of organic substrates to produce valuable chemicals is of utmost importance as a means of establishing green chemical syntheses. Inspired by the active Ni 3+ intermediates involved in electrocatalytic water oxidation by nickel‐based materials, we prepared NiB x as a catalyst and used water as the oxygen source for the oxygenation of various organic compounds. NiB x was further employed as both an anode and a cathode in a paired electrosynthesis cell for the respective oxygenation and hydrogenation of organic compounds, with water as both the oxygen and hydrogen source. Conversion efficiency and selectivity of ≥99 % were observed during the oxygenation of 5‐hydroxymethylfurfural to 2,5‐furandicarboxylic acid and the simultaneous hydrogenation of p ‐nitrophenol to p ‐aminophenol. This paired electrosynthesis cell has also been coupled to a solar cell as a stand‐alone reactor in response to sunlight.

A 64-fold improved efficiency of solar-to-hydrogen conversion (SHC) was achieved via exposing Au nanoparticles (NPs) on the {001} facets of anatase TiO 2 nanosheets. The SHC follows a surface plasmon resonance-mediated electron injection mechanism, where Au NPs can not only harvest visible light and convert them to free energetic electrons, but promote the SHC by increasing the electron-hole pair formation rate driven by the electromagnetic field formed nearby the semiconductor.

Water‐splitting photoanodes based on semiconductor materials typically require a dopant in the structure and co‐catalysts on the surface to overcome the problems of charge recombination and high catalytic barrier. Unlike these conventional strategies, a simple treatment is reported that involves soaking a sample of pristine BiVO4 in a borate buffer solution. This modifies the catalytic local environment of BiVO4 by the introduction of a borate moiety at the molecular level. The self‐anchored borate plays the role of a passivator in reducing the surface charge recombination as well as that of a ligand in modifying the catalytic site to facilitate faster water oxidation. The modified BiVO4 photoanode, without typical doping or catalyst modification, achieved a photocurrent density of 3.5 mA cm−2 at 1.23 V and a cathodically shifted onset potential of 250 mV. This work provides an extremely simple method to improve the intrinsic photoelectrochemical performance of BiVO4 photoanodes.

Low-cost transition metal-based electrocatalysts for water oxidation and understanding their structure−activity relationship are greatly desired for clean and sustainable chemical fuel production. Herein, a core− shell (CS) NiFeCr metal/metal hydroxide catalyst was fabricated on a 3D Cu nanoarray by a simple electrodeposition−activation method. A synergistic promotion effect between electronic structure modulation and nanostructure regulation was presented on a CS-NiFeCr oxygen evolution reaction (OER) catalyst: the 3D nanoarchitecture facilitates the mass transport process, the in situ formed interface metal/metal hydroxide heterojunction accelerates the electron transfer, and the electronic structure modulation by Cr incorporation improves the reaction kinetics. Benefiting from the synergy between structural and electronic modulation, the catalyst shows excellent activity toward water oxidation under alkaline conditions: overpotential of 200 mV at 10 mA/cm 2 current density and Tafel slope of 28 mV/dec. This work opens up a new window for understanding the structure−activity relationship of OER catalysts and encourages new strategies for development of more advanced OER catalysts.

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