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Exploring cheap and efficient cocatalysts is particularly important for a photoanode during photoelectrochemical (PEC) water splitting. Herein, we demonstrate that composite CoOx/CuO cocatalyst could efficiently enhance the oxygen evolution activity of BiVO4. The onset potential of BiVO4 shifts negatively from 0.42 to 0.38 V vs. the reversible hydrogen electrode (RHE), and the photocurrent of BiVO4 increases from 0.42 mA cm−2 to 1.58 mA cm−2 at 1.23 V vs. RHE, which increases by about 3.76 times. It was confirmed by subsequent electrochemical and physical characterization that the charge separation and injection efficiency were improved, and the IPCE was also improved. Systematic studies indicate that composite CoOx/CuO cocatalyst exhibits better performance than the single CoOx or CuO cocatalyst for promoting the separation of electron‐hole, and accelerating the surface water oxidation reaction. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting can convert solar energy into clean and renewable hydrogen energy, showing a promising application prospect. However, large‐scale implementation of PEC water splitting is now hampered by insufficient solar‐to‐hydrogen conversion efficiency, which requires the development of high‐performance photoelectrodes. Key processes that determine the water splitting performance of photoelectrodes are the light absorption, separation, and transport efficiency of photogenerated electrons and holes and the surface reaction of water oxidation/reduction. Concerning these three key processes, various material design and surface/interface engineering strategies have been explored to improve the performance of photoelectrodes. Herein, these strategies for photoelectrode optimization of the past decades are summarized and discussed in terms of micro‐ and nanostructuring, heterojunction construction, element doping, surface passivation, plasmonic metal coating, and electrocatalyst modification. Special attention is given to how these strategies play their roles in improving the performance of photoelectrodes, based on which it is hoped light is shed on the design principles and modification routes for high‐performance photoelectrodes. [ABSTRACT FROM AUTHOR]

Bismuth vanadate photoanodes often suffer from poor electron transport, which restricts their photoelectrochemical performance in water oxidation. Here, reduced graphene oxide sheets with excellent electronic conductivity are introduced to bismuth vanadate photoanode films to provide a channel for electron transport. As a result, the charge separation efficiency of the photoanode films increases from 59 to 78 % at 420 nm and 1.23 V (vs. the reversible hydrogen electrode) under back irradiation. In particular, the onset potential for photoelectrochemical water oxidation over reduced graphene oxide-bismuth vanadate photoanode films has a cathodic shift of approximately 120 mV in potassium borate electrolyte compared to bare bismuth vanadate photoanode films. [ABSTRACT FROM AUTHOR]