All-Solution-Processed WO/BiVO Core-Shell Nanorod Arrays for Highly Stable Photoanodes.

Tungsten oxide (WO) and bismuth vanadate (BiVO) are one of the most attractive combinations to construct an efficient heterojunction for photoelectrochemical (PEC) applications. Here, we report an all-solution-processed WO/BiVO heteronanostructure photoanode with highly enhanced photoactivity and stability for sustainable energy production. The vertically aligned WO nanorods were synthesized on a fluorine-doped tin oxide/glass substrate by the hydrothermal method without a seed layer and BiVO was deposited by pulsed electrodeposition for conformal coating. Owing to the long diffusion lengths of charge carriers in the WO nanorods, the ability to absorb the wider range of wavelengths, and appropriate band-edge positions of the WO/BiVO heterojunction for spontaneous PEC reaction, the optimum WO/BiVO photoanode has a photocurrent density of 4.15 mA/cm at 1.23 V versus RHE and an incident-photon-to-current efficiency of 75.9% at 430 nm under front illumination, which are a double and quadruple those of pristine WO nanorod arrays, respectively. Our work suggests an environment-friendly and low-cost all-solution process route to synthesize high-quality photoelectrodes.