Photocatalytic properties of BiOBr/g-C3N4 heterojunctions originated from S-scheme separation and transfer of interfacial charge pairs

Construction of heterojunctions is an available approach to overcome the defects of a single photocatalyst. In this work, BiOBr/g-C3N4 S-scheme heterojunctions were prepared by a microwave hydrothermal approach. The crystal structures, morphologies, and photoinduced charge separation behavior of the BiOBr/g-C3N4 heterojunctions were studied by some analytic techniques. The experimental results reveal that all the BiOBr/g-C3N4 heterojunctions display superior photocatalytic activities to g-C3N4 and BiOBr under visible light exposure, in particular, the sample with 2% molar ratio of BiOBr/g-C3N4 presents the highest photocatalytic performance. The boosted photocatalytic property of BiOBr/g-C3N4 heterojunctions is ascribed to S-scheme segregation and transfer of interfacial charge pairs. Following this mechanism, the efficient segregation of photogenerated carriers can be achieved, at the same time, the robust redox ability of photo-generated e−/h+ pairs can be maintained. This work contributes a reference to develop highly efficiency g-C3N4 based photocatalyst for photocatalytic decomposition of contaminants.