The CuSCN layer between BiVO4 and NiFeOx for facilitating photogenerated carrier transfer and water oxidation kinetics

Modification of oxygen evolution co-catalyst (OEC) on the surface of bismuth vanadate (BiVO 4 ) can effectively improve the kinetics of water oxidation, but it is still limited by the small hole extraction driving force at the BiVO 4 /OEC interface. Modulating the BiVO 4 /OEC interface with a hole transfer layer (HTL) is expected to facilitate hole transport from BiVO 4 to the OEC surface. Herein, a copper(I) thiocyanate (CuSCN) HTL is inserted between BiVO 4 and NiFeO x OEC to create BiVO 4 /CuSCN/NiFeO x photoanode, resulting in a significant enhancement of photoelectrochemical (PEC) water splitting performance. From electrochemical analyses and density functional theory (DFT) simulations, the markedly enhanced PEC performance is attributed to the insertion of CuSCN as an HTL, which promotes the extraction of holes from BiVO 4 surface and boosts the water oxidation kinetics. The optimal photoanode achieves a photocurrent density of 5.6 mA cm −2 at 1.23 V versus the reversible hydrogen electrode (vs. RHE) and an impressive charge separation efficiency of 96.2 %. This work offers valuable insights into the development of advanced photoanodes for solar energy conversion and emphasizes the importance of selecting an appropriate HTL to mitigate recombination at the BiVO 4 /OEC interface.