FeCoW multimetal oxide-coated W:BiVO4 photoanode for efficient oxygen evolution

Abstract

BiVO₄ is one of the most promising photoanode materials due to its relatively small band gap (∼2.4 eV) for efficient light absorption, and its suitable valence band edge for the oxygen evolution reaction. However, it achieves a photocurrent which is much lower than the theoretical value of 7.5 mA cm⁻². Herein we prepare a multimetal oxide-based heterojunction W:BiVO₄–FeCoW by a sol–gel approach with post-annealing. The heterojunction photoanode exhibits a photocurrent which is enhanced to ∼3.8 times that of a W:BiVO₄ photoanode at 1.23 V vs. the reversible hydrogen electrode (RHE), and a significant negative shift of the flat-band potential of 280 mV. The experimental results demonstrate that the performance enhancement mechanism can be attributed to the significantly enhanced charge separation/transport and light absorption due to the multimetal oxide-modified heterojunction.