P-doped bismuth sulfide for improved photocatalytic degradation of bisphenol A: Role of built-in electric field and S vacancies

Efficient and stable photocatalytic materials are crucial for advancing photocatalytic technology. While bismuth sulfide has garnered significant attention in recent years, its poor electron-hole separation and rapid recombination have hindered its effectiveness. In this paper, a phosphorus (P)-doped bismuth sulfide is used to establish a ternary bismuth phosphosulfide (FGBS1-XPX) photocatalyst. The successful incorporation of P into bismuth sulfide was verified through SEM-EDX, XRD, and XPS analyses. The P doping generates a built-in electric field on the catalyst surface, which can effectively extract carriers. Additionally, it was demonstrated by Mott-Schottky test, EPR and PL that P doping shortens the gap between the catalyst's impurity energy level and Fermi energy level, making the S vacancies level an effective electron capture center. This results in improved separation efficiency of electron-hole pairs and a delay in the lifetime of charge carriers. The optimal degradation rate for a 15 ppm BPA solution using 0.6 g/L of 1FGBS1-XPX was 80% within 4 h, demonstrating significantly improved photocatalytic activity. This was due to the synergistic action of the built-in electric field and S vacancies induced by P doping. The idea of utilizing P doping and S vacancies synergism to enhance photocatalytic performance provides a new approach for designing photocatalysts with improved electron-hole separation.