A tandem photoelectrochemical water splitting cell consisting of CuBi2O4 and BiVO4 synthesized from a single Bi4O5I2 nanosheet template

Abstract

We report on a simple and facile synthetic approach for preparing both a CuBi₂O₄ photocathode and BiVO₄ photoanode from a single Bi₄O₅I₂ nanosheet template. A nanosheet structured Bi₄O₅I₂ (nanoBi₄O₅I₂) template, solvothermally deposited on a conducting glass substrate, can be converted to a textured CuBi₂O₄ photocathode and a BiVO₄ photoanode with coral-like nanostructure by drop-casting a copper ion-containing and a vanadium ion-containing solution, respectively, with a follow-up heat treatment. UV-vis absorption spectra and Mott–Schottky analyses confirm CuBi₂O₄ and BiVO₄ have well-suited band gaps for absorbing a large portion of visible light and complementary band structures for proton reduction and water oxidation, respectively. A photoelectrochemical tandem cell, consisting of a cobalt based catalyst modified CuBi₂O₄ photocathode and a cobalt based catalyst modified BiVO₄ photoanode shows promising photoelectrochemical properties towards water splitting, and can be operated without an external bias. Factors limiting the performance of the tandem cell are also discussed.