Bulky crystalline BiVO4 thin films for efficient solar water splitting

Abstract

We report a new fabrication method of flat, uniform BiVO₄ films on an electrically conductive transparent indium tin oxide (ITO) film based on a solution process for depositing bismuth precursor films and a high-temperature calcination process with an organic vanadium precursor. The synthesised BiVO₄ films, composed as a monolayer of crystallites (diameter ≤ 1 μm) fixed on the ITO, realised half-cell solar-to-hydrogen energy conversion efficiencies of over 1.5% by the aid of impregnated CoO_x and atomic-layer-deposited NiO when tested as oxygen-evolving photoanodes for water splitting under solar simulator AM 1.5G illumination. Stoichiometric oxygen and hydrogen were generated with Faraday efficiencies of unity over 12 h at 0.6–0.9 V_RHE. This morphology of our bulky semi-transparent BiVO₄ films exhibited state-of-the-art solar water splitting performances.