Thickness-ultrathin and bismuth-rich strategies for BiOBr to enhance photoreduction of CO2 into solar fuels

Abstract Two dimension layered BiOX (X = Cl, Br, I) semiconductor nanomaterials are very important photocatalysts. Our previous work showed that thickness-ultrathin and bismuth-rich strategies are excellent methods to improve the visible-light-driven (VLD) photocatalytic reduction activity of BiOX. In this study, thickness-ultrathin and bismuth-rich strategies were ingenuously combined to enhance the photocatalytic performance of the photocatalyst, via a glycerol precursor route, Bi 4 O 5 Br 2 microsphere assembled by ultrathin nanosheets was synthesized and characterized by X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), time-resolved PL spectra and UV–vis diffuse reflectance spectra (DRS). The thickness of Bi 4 O 5 Br 2 ultrathin nanosheets was about 3.7 nm, which was much thinner than the common BiOBr nanosheets (65 nm). Due to the thickness-ultrathin and bismuth-rich strategies, the synthesized Bi 4 O 5 Br 2 sample displayed a higher photocatalytic reduction activity of CO 2 conversion than BiOBr and ultrathin BiOBr under visible-light irradiation. More importantly, we found that thickness-ultrathin and bismuth-rich strategies played different roles. Thickness-ultrathin strategy only can increase the CO generation while bismuth-rich strategy only can increase the CH 4 generation for photoreduction of CO 2 .