Highly efficient photocatalysts constructed by rational assembly of dual-cocatalysts separately on different facets of BiVO4

Abstract

Cocatalysts play important roles in promoting the catalytic reactions of semiconductor photocatalysts. Especially, deposition of dual cocatalysts, i.e., oxidation and reduction cocatalysts, onto a semiconductor photocatalyst can significantly improve its photocatalytic activity due to the synergetic effect of rapid consumption of photogenerated electrons and holes. However, in most cases, the cocatalysts are randomly deposited onto the semiconductor photocatalysts, where the cocatalysts cannot function fully. Herein, based on the findings that photogenerated electrons and holes can be spatially separated onto the different facets of BiVO₄, we have successfully prepared two types of photocatalysts (M/MnO_x/BiVO₄ and M/Co₃O₄/BiVO₄, where M stands for noble metals) with reduction and oxidation cocatalysts selectively deposited onto the {010} and {110} facets of BiVO₄ by a photo-deposition method. Remarkably enhanced photocatalytic activities were observed for such assembled photocatalysts in control experiments of photocatalytic water oxidation and photocatalytic degradation of methyl orange and rhodamine B. In-depth investigations show that the enhanced photocatalytic performances are due to not only the intrinsic nature of charge separation between the {010} and {110} facets of BiVO₄, but also the synergetic effect of dual-cocatalysts deposited onto the different facets of BiVO₄. This work further proves the feasibility of the general concepts for approaching efficient artificial photosynthesis systems, namely, engineering of crystal-based photocatalysts by selective deposition of suitable reduction and oxidation cocatalysts onto the different facets of light absorbing semiconductor crystals.