Bi2S3-decorated three-dimensional BiOCl as a Z-scheme heterojunction with highly exposed {001} facets of BiOCl for enhanced visible-light photocatalytic performance

Abstract

Bi-based photocatalysts are widely applied in energy and environmental fields by virtue of their excellent oxidation ability. However, there is still no effective method to construct Z-scheme heterojunctions and regulate the surface simultaneously. Herein, a series of BiOCl/Bi₂S₃ photocatalysts were prepared in a controlled manner via a bottom-up strategy. The higher exposure degree of the {001} facets of BiOCl in the composites was confirmed by XRD. According to TEM and HRTEM, Bi₂S₃ quantum dots were uniformly loaded on the surface of BiOCl, and the heterojunction was successfully constructed between them. The photocatalytic performances of the composites were evaluated by the degradation of tetracycline (TC) under visible light irradiation. It was found that the degradation rate of BOC-BS-5 was 4.1 and 11.5 times those of BiOCl and Bi₂S₃, respectively. Moreover, BOC-BS-5 presented excellent stability after four cycle experiments. The remarkable photocatalytic performance could be attributed to the Z-scheme heterojunction, which was confirmed by ESR. The Z-scheme heterojunction retained a strong reduction–oxidation activity and displayed a high charge separation efficiency. For another, according to XPS, the oxygen vacancies in composites were significantly increased, which could promote charge transfer and further improve the photocatalytic performance. Furthermore, ˙O₂⁻ and ˙OH were identified to be the main reactive oxygen species in the degradation process.