A novel Sillén-structured Bi-based oxybromide: CdBiO₂Br ultrathin nanosheets for enhanced photocatalytic activity

According to the typical Sillén-structured BiOBr, a simple solvothermal method was used to successfully synthesise Sillén-structured bimetallic oxyhalide CdBiO₂Br with the existence of 1-hexadecyl-3-methylimidazolium bromide ([C₁₆mim]Br), a kind of reactive ionic liquid. The introduction of the metal cadmium, which can form Sillén-structured bimetallic oxyhalide, made the alternating structure of BiOBr originally [Bi₂O₂]²⁺ and bilayer Br^- modified to that of [CdBiO₂]⁺ and monolayer Br^-. So that the distance between layer and layer is greatly shortened, which facilitates the migration and separation of photogenerated carriers and promotes the generation of more reactive oxygen species. After modification, the band positions of CdBiO₂Br materials can make more full use of visible light and more favourable utilisation of solar resources. As confirmed by radical trapping analysis and ESR analysis, superoxide radical (·O₂^-) and hole (h⁺) acted the major part during photocatalysis. The possible intermediate products that appeared during the degradation progress were analyzed by LC-MS. Moreover, the generation of superoxide ions was quantitatively analyzed by nitroblue tetrazolium chloride (NBT). In this paper, we present an ultra-thin layered material for visible light catalysis, which enlightens a feasible scheme for the research and development of new layered photocatalytic materials.