A tandem photoelectrochemical water splitting cell consisting of CuBiO and BiVO synthesized from a single BiOI nanosheet template.

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.