Efficient photoelectrochemical water oxidation using a TiO 2 nanosphere-decorated BiVO 4 heterojunction photoanode

Abstract

Constructing heterojunctions by coupling dissimilar semiconductors is a promising approach to boost charge separation and charge transfer in photoelectrochemical (PEC) water splitting. In this work, we fabricated a highly efficient TiO 2 /BiVO 4 heterojunction photoanode for PEC water oxidation via a simple hydrothermal method. The resulting heterojunction photoanodes show enhanced PEC performance compared to the bare BiVO 4 due to the simultaneous improvements in charge separation and charge transfer. Under simulated sunlight illumination (AM 1.5G, 100 mW cm −2 ), a high photocurrent of 3.3 mA cm −2 was obtained at 1.23 V (vs. the reversible hydrogen electrode (RHE)) in a neutral solution, which exceeds those attained by the previously reported TiO 2 /BiVO 4 heterojunctions. When a molecular Co-cubane catalyst was immobilized onto the electrode, the performance of the TiO 2 /BiVO 4 heterojunction photoanode can be further improved, achieving a higher photocurrent density of 4.6 mA cm −2 at 1.23 V, an almost three-fold enhancement over that of the bare BiVO 4 . These results engender a promising route to designing an efficient photoelectrode for PEC water splitting.