Insight into facet-dependent photocatalytic H2O2 production on BiOCl nanosheets

Abstract

Hydrogen peroxide is an important high-energy product widely used in various fields. Highly efficient semiconductor photocatalysts, especially those that can produce H₂O₂ both from water oxidation and O₂ reduction, are eagerly desired. In this work, BiOCl nanosheets with preferentially exposed (001) and (010) facets were synthesized via a simple hydrothermal method. The facet-dependent photocatalytic H₂O₂ generation activities of these BiOCl nanosheets were assessed. The hydrogen peroxide evolution rate of BiOCl(001) is about 2-fold higher than that of BiOCl(010), which is assigned to the higher separation efficiency of photogenerated charge carriers. Interestingly, both the EPR study and active species trapping experiments demonstrate that the generation of H₂O₂ on the BiOCl(001) photocatalyst mostly originates from sequential two step single-electron O₂ reduction, while there are two pathways for photocatalytic H₂O₂ production on BiOCl(010), from both oxygen reduction and water oxidation. This work offers a new strategy to pursue highly efficient semiconductor photocatalysts with two pathways for H₂O₂ production from both water oxidation and O₂ reduction.