Boosting carrier dynamics of BiVO4 photoanode via heterostructuring with ultrathin BiOI nanosheets for enhanced solar water splitting

Bismuth vanadate (BiVO4) has been one of the most promising candidates for solar water splitting while still suffers from poor bulk charge transport that limits its solar to hydrogen conversion efficiency. We demonstrate in this work an efficient strategy for boosting bulk charge transport of BiVO4 through the facile impregnation of as-prepared BiVO4 photoanode in the precursor solution of ultrathin BiOI nanosheets. Such impregnation creates increased oxygen vacancies in the bulk of BiVO4 through the reduction of V5+ to V4+ by I-, which greatly improves bulk separation efficiency for BiVO4-BiOI up to 65.9 % at 1.23 V-RHE from the original 51.9 % of pure BiVO4. Moreover, the decoration of the BiOI nanosheets on BiVO4 photoanode is also beneficial for addressing the carrier dynamics at surface due to the matched energy levels of BiOI nanosheets and BiVO4. The introduced plenty of oxygen vacancies in the bulk of BiVO4 and the built-in electric field in BiVO4-BiOI synergistically improve the photocurrent density at 1.23 V-RHE up to 3.88 mA cm(-2). We believe that such facile impregnation strategy will pave an alternative way to the development of highly efficient BiVO4 photoanode. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, an efficient strategy for boosting bulk charge transport of BiVO4 through impregnation of BiVO4 in BiOI nanosheets precursor solution was demonstrated. The introduction of oxygen vacancies in the bulk of BiVO4 and the built-in electric field in BiVO4-BiOI synergistically improved the photocurrent density. This facile impregnation strategy is believed to pave an alternative way to the development of highly efficient BiVO4 photoanode.