Role of graphene on the surface chemical reactions of BiPO4–rGO with low OH-related defects

Abstract

Graphene has been widely introduced into photocatalysis to enhance photocatalytic performance due to its unique physical and chemical properties. However, the effect of graphene on the surface chemical reactions of photocatalysis has not been clearly researched, which is important for photocatalysis because photocatalytic reactions ultimately occur on the catalyst surface. Herein, a two-step solution-phase reaction has been designed to synthesize quasi-core–shell structured BiPO₄–rGO cuboids and the role of graphene on the surface chemical reactions was investigated in detail. It was found that the introduced graphene modified the process and the mechanism of the surface chemical reactions. The change mainly originates from the interaction between graphene and the adsorbed O₂ molecule. Due to the electron transfer from graphene to adsorbed O₂, graphene could tune the interfacial charge transport and efficiently activate molecular oxygen to form O₂˙⁻ anions as the major oxidation species instead of ˙OH. In addition, the two-step synthesis approach could efficiently suppress the formation of OH-related defects in the lattice. As a result, the BiPO₄–rGO composite exhibited superior photocatalytic activity to BiPO₄ and P25, about 4.3 times that of BiPO₄ and 6.9 times that of P25.