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The quest for developing electrochemical energy‐storage and ‐conversion technologies continues to be a great impetus to develop cost‐effective, highly active, and electrochemically stable electrocatalysts for overcoming the activation energy barriers of the oxygen evolution reaction (OER). Co3O4 nanocrystals have great potential as OER catalysts, and research efforts on improving the catalytic activity of Co3O4 are currently underway in many laboratories. Herein, CoFe layered double hydroxide (LDH) nanosheets were directly grown on the active Co3O4 substrate to form nanohybrid electrocatalysts for OER. The CoFe LDH/Co3O4(6:4) nanohybrid exhibited superior catalytic performance with a low overpotential and a small Tafel slope in alkaline solution. The outstanding performance of the CoFe LDH/Co3O4(6:4) nanohybrid was primarily owing to the synergistic effects induced by the strongly coupled interface between CoFe LDH and Co3O4; this feature enhanced the intrinsic OER catalytic activity of the nanohybrid and favored fast charge transfer. Compared with other Co3O4‐based catalysts, the nanohybrid shows advantages and offers a feasible avenue for improving the activity of Co3O4‐based catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Bismuth vanadate (BiVO4) has triggered extensive interest in photoelectrochemical (PEC) water splitting, owing to its narrow band gap and sufficiently positive valence band. However, some defects still exist to block the solar utilization efficiency and hydrogen evolution kinetics. Herein, the NiMoO4 semiconductor is combined with a BiVO4 photoanode, for the first time, and excellent PEC performance is achieved on the basis of heterojunction formation and favorable conductivity of NiMoO4. In addition, it has been demonstrated that NiMoO4 promotes the light absorption ability, charge separation efficiency, and surface charge‐transfer efficiency comprehensively. To further improve the photoconversion efficiency, cobalt phosphate, as an oxygen evolution reaction cocatalyst, is deposited on the above electrode and achieves a much enhanced utilization efficiency of 1.18 %, with a photocurrent density of 5.3 mA cm−2 at 1.23 V versus a reversible hydrogen electrode; this exceeds most results reported to date. This rational and unique photoanode construction provides a new thread for the photoelectrode designation. [ABSTRACT FROM AUTHOR]

Abstract: The photoelectrochemical (PEC) water‐splitting efficiency of a hematite‐based photoanode is still far from the theoretical value due to its poor surface reaction kinetics and high density of surface trapping states. To solve these drawbacks, a photoanode consisting of NiO nanoparticles anchored on a gradient phosphorus‐doped α‐Fe2O3 nanorod (NR) array (NiO/P‐α‐Fe2O3) was fabricated to achieve optimal light absorption and charge separation, as well as rapid surface reaction kinetics. Specifically, a photoanode with the NR array structure allowed a high mass‐transport rate to be achieved, while phosphorus doping effectively decreased the number of surface trapping sites and improved the electrical conductivity of α‐Fe2O3. Furthermore, the p–n junction that forms between NiO and P‐α‐Fe2O3 can further improve the PEC performance due to efficient hole extraction and the water oxidization catalytic activity of NiO. Consequently, the NiO/P‐α‐Fe2O3 NR photoanode produced a high photocurrent density of 2.08 mA cm−2 at 1.23 V versus a reversible hydrogen electrode and a 110 mV cathodic shift of the onset potential. This rational design of structure offers a new perspective in exploring high‐performance PEC photoanodes. [ABSTRACT FROM AUTHOR]