HCl post-processing BiOBr photocatalyst: Structure, morphology, and composition and their impacts to activity

This work reports a systematic investigation on the structure, morphology, and composition, and their impacts on photocatalytic performance, for a HCl post-processing BiOBr photocatalyst. We dispersed BiOBr powders into different concentration HCl aqueous solutions to synthesize a series of samples at room temperature. With the HCl concentration increasing, SEM images revealed that as-prepared flower-like BiOBr microspheres transformed gradually into the interweaved nanosheets, and ultimately, obtaining the stacked nanosheet structures. The XRD, EDX, BET, UV-vis DRS and photocurrent data demonstrated that HCl post-processing had in-deep effects on the element composition, specific surface area, optical property and photoelectrochemical properties of samples. Moreover, the detailed formation mechanism and good correlations among their structure, composition, morphology, and enhanced activity have been established by degrading methyl orange (MO) dye molecules under simulated solar light. The HCl post-processing BiOBr samples exhibited better photocatalytic activity and stability than the pure BiOBr sample. Results indicate that there is particular emphasis placed on the roles of H⁺ and Cl^- ions in the micro- and macro-performance improvements of BiOBr photocatalysts. Our findings should provide important knowledge for further understanding the roles of H⁺ and Cl^- ions in such 'like-BiOX' layered-structure systems.