BiOBr–BiOI microsphere assembled with atom-thick ultrathin nanosheets and its high photocatalytic activity

Abstract

BiOBr–BiOI composite microspheres assembled with atom-thick ultrathin nanosheets have been synthesized via a simple solvothermal route with the surfactant polyvinylpyrrolidone (PVP). The structure was characterized with AFM, which confirmed the 0.9 nm thickness of the single-layered nanosheets. The ultrathin structure with atomic thickness mainly relies on its lamellar structure and the reason for the formation of the few- or even single-layered structure is the strong intra-layer chemical bonding and weak inter-layer interaction. The 3D BiOBr–BiOI exhibits excellent photocatalytic activity for BPA degradation under visible light irradiation. Nearly 80% of BPA was degraded in 2 h irradiation, and over 90% after 5 h. Based on these findings, the photodegradation mechanism was investigated and O₂⁻ was suggested to be the main active oxidant in the BPA-removal processes. Our investigation showed that the electron–hole pairs on ultrathin nanosheets can be separated effectively which resulted in significantly promoted solar-driven photocatalytic activity for extremely low photocatalyst loading.