Improved Charge Separation and Injection Efficiencies of Bismuth Vanadate Photoanode by Depositing Composite CoO _x /CuO Cocatalyst

Abstract Exploring cheap and efficient cocatalysts is particularly important for a photoanode during photoelectrochemical (PEC) water splitting. Herein, we demonstrate that composite CoO x /CuO cocatalyst could efficiently enhance the oxygen evolution activity of BiVO 4 . The onset potential of BiVO 4 shifts negatively from 0.42 to 0.38 V vs. the reversible hydrogen electrode (RHE), and the photocurrent of BiVO 4 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 CoO x /CuO cocatalyst exhibits better performance than the single CoO x or CuO cocatalyst for promoting the separation of electron‐hole, and accelerating the surface water oxidation reaction.