Photoelectrochemical performance of W-doped BiVO4 photoanode

Abstract

One of the crucial challenges in enhancing the photoelectrochemical (PEC) water splitting performance of BiVO4 photoanode is to improve the charge separation and transfer efficiency. Therefore, in this paper, a novel multilayer gradient W-doped BiVO4 photoanode is fabricated for improved performances in solar water splitting. Firstly, different amounts of W mono-doped BiVO4 photoanodes are prepared, and the W (5%)-doped BiVO4 photoanode reaches highest photocurrent density of 0.61 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE). Compared with the photocurrent density of the pure BiVO4 photoanode (0.28 mA cm−2), the enhancement can be attributed to the doped W which acts as an electron donor that could reduce the surface charge transfer resistance and facilitate charge transfer. Furthermore, multilayer gradient W-doped BiVO4 photoanodes are prepared to enhance PEC performances. The BVO-530 achieves a photocurrent density of 1.17 mA cm−2 at 1.23 V versus RHE due to the multilayer gradient structure which forms a diffusion path for electron–holes caused by the gradual increase in the Fermi level. The mechanisms of multilayer gradient W-doped BiVO4 photoanodes are discussed in detail based on PEC measurements. This work provides a new strategy for designing and fabricating photoanode systems to enhance the charge separation and transport for efficient water splitting.