Construction of inhomogeneous bismuth-based heterojunctions with efficient interfacial charge transport: Bridging of BiOX.

The inefficiency of photogenerated charge transfer between heterojunction interfaces imposes significant limitations on the activity of photocatalytic materials. In this paper, Bi2WO6-Bi2O2SiO3-Bi12SiO20-BiOXY (X = Cl, Br, Y=I) (BSBI and BSCI) heterojunctions were successfully constructed by utilizing the structural similarity of Bi-based materials. The effects of different halide species, concentrations and volume ratios on their photocatalytic performance were investigated. The results showed that the optimized BSBI heterojunction obtained by multilayer substitution exhibited excellent photocatalytic activity, which achieved up to 99.3 % degradation of rhodamine B (Rh B, 10 mg/L) under 60 min of simulated sunlight, 85.4 % degradation of norfloxacin (NFX, 10 mg/L) within 120 min and 85.3 % degradation of tetracycline hydrochloride (TCH, 10 mg/L) within 120 min. The enhanced photocatalytic performance was attributed to the ion-exchange-induced multilayer replacement. The generated BiOX effectively solved the problem of insufficient charge transfer driving force caused by the minor potential difference and the large interfacial resistance at the heterogeneous interfaces of Bi2O2SiO3-Bi12SiO20 and Bi2WO6 through the "bridging" effect, which significantly improved the carrier transport efficiency between the heterojunctions. This work provides a valuable methodology and basis for constructing bismuth-based multi-heterojunction interfaces with efficient charge transfer.