Assessing the Suitability of Copper Vanadate (Cu₁₁V₆O₂₆) for Use as a Photoanode Material for Photoelectrochemical Water Oxidation

One of the most promising methods to store and utilize sunlight energy is to convert it into hydrogen via water splitting reaction. In this study, pure-phase Cu11V6O26 thin film photoanodes were prepared on a FTO-coated glass substrate for the first time by a low-cost solution-based spray pyrolysis method. The optical bandgap, band positions, flatband potential, chemical composition, photocurrent onset potential, photocurrent generation, incident photon to current conversion efficiency, photoelectrochemical stability, and O2 production Faradic efficiency of Cu11V6O26 were systematically researched. UV–vis results showed that Cu11V6O26 has an ideal bandgap of ∼1.85 eV, which corresponds to a theoretical photocurrent of up to 15 mA/cm2 for solar water splitting. Photoelectrochemical measurements showed the onset of a photoanodic current driven under AM 1.5 illumination and reaching incident-photon-to-current efficiencies exceeding ∼4% in near-neutral (pH 6.8) aqueous solutions. Meanwhile, the Cu11V6O26 photoelectrodes showed excellent photoelectrochemical stability and nearly quantitative Faradic efficiency, which suggest that Cu11V6O26 could be a promising photoanode material. The results of this study will significantly increase our fundamental understanding of Cu11V6O26 performance in solar water splitting reactions. Moreover, these data could be transferred to other ternary metal oxides for the same applications.