Creation of oxygen vacancies to activate 2D BiVO4 photoanode by photoassisted self-reduction for enhanced solar-driven water splitting

BiVO4 is regarded as a promising photoanode material because of its narrow band gap (- 2.4 eV). How-ever, the poor bulk carrier transport capacity severely limits the actual performance of BiVO4 in pho-toelectrochemistry (PEC) water splitting. Here, we tried to synthesize two-dimensional (2D) morphol-ogy by adding structure-directing agents to hydrothermal solution and introduce oxygen vacancies by photoassisted self-reduction. In the scheme, the 2D morphology can shorten the carrier diffusion length and the construction of oxygen vacancies can increase the bulk carrier concentration. Through the com-bined effect of both, the inherent poor carrier transport capacity of BiVO4 has been improved, which has been proven by Electrochemical Impedance Spectroscopy (EIS), Intensity Modulated Photocurrent Spec-troscopy (IMPS) and Mott-Schottky (M-S) plots. At 1.23 V vs. RHE, the photocurrent density increases from-1.60 mA/cm(2) (2D BiVO4) to similar to 2.30 mA/cm(2) [2D BiVO4(V-ox)], which is 8 times larger than that of bare BiVO4(0.3 mA/cm(2)). The incident photon-to-current efficiencies (IPCE) of 2D BiVO4(V-ox) have reached the value of 46% (at 350 nm). The carrier separation efficiency (eta(sep)) and carrier injection efficiency (eta(inj)) have been improved up to 49% and 68%, respectively. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

By synthesizing a two-dimensional morphology and introducing oxygen vacancies, the carrier transport capacity of BiVO4 has been improved, enhancing its performance in PEC water splitting.