rGO-modified BiOX (X = Cl, I, Br) for enhanced photocatalytic eradication of gaseous mercury

Photocatalytic oxidation of gaseous heavy metals is an efficient approach to alleviate energy crises and environmental pollution. In this study, a novel two-step solvothermal method was designed to synthesize reduced graphene oxide (rGO)-modified bismuth oxyhalide (BiOX, X = Cl, I, Br) nanosheets. The modification of rGO led to the significant enhancement in the specific surface area of BiOX nanosheets, reduction in the bandgap, improvements in the light absorption range and intensity, acceleration in the photogenerated carrier separation rate, and reduction in the photogenerated electron − hole complexation. Furthermore, both O2– and OH were demonstrated to be active species in the reaction. Owing to these achievements, all samples displayed significantly improved photocatalytic performance. Furthermore, the rGO-modified samples exhibited excellent stability and maintained the highest mercury removal efficiency after several cycles. However, the samples prepared in this research displayed a high level of moisture resistance. These characteristics of BiOX-based materials make them potential candidates for the photocatalytic removal of heavy metals from industrial waste gases.