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

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