The Cuscn Layer between Bivo4 and Nifeox for Facilitating Photogenerated Carrier Transfer and Water Oxidation Kinetics

Abstract

Modification of the oxygen evolution cocatalyst (OEC) on BiVO4 surface can effectively enhance the kinetics of water oxidation, but it is still limited by the small hole extraction driving force at the BiVO4/OEC interface. Modulating the OEC/BiVO4 interface with a hole transfer layer (HTL) is expected to drive hole transfer from BiVO4 to the OEC surface, thus achieving efficient photoelectrochemical (PEC) water splitting. Herein, a Copper(I) thiocyanate (CuSCN) HTL was inserted between BiVO4 and NiFeOx OEC to form BiVO4/CuSCN/NiFeOx photoanode, resulting in a decent photocurrent enhancement. From electrochemical analyses and density functional theory (DFT) calculations, the high PEC performance is attributed to the incorporation of CuSCN as HTL, promoting the extraction of holes from BiVO4 surface and accelerating the water oxidation kinetics. The optimized photoanode exhibited a photocurrent density of 5.65 mA cm-2 at 1.23 V vs RHE with a charge separation efficiency of 96.2%. This work provides insights into the design of viable high performance photoanodes for solar energy conversion by advocating the selection of a suitable hole transfer layer to eliminate the OEC/BiVO4 interfacial recombination.

Keywords: Hole transfer layer, Copper(I) thiocyanate, BiVO4 photoanode, Photoelectrochemical water splitting, Oxygen evolution