In Situ Fabrication of BiOCl@Bi2S3@ZnIn2S4 Double Z-Scheme Heterojunctions for Enhanced Photocatalytic Degradation Performance.

Organic pollutants in industrial wastewater present a severe threat to both the environment and human health. Photocatalytic technology, recognized for its eco-friendliness and high efficiency, has become a leading approach for degrading such pollutants. In this work, BiOCl nanosheets were first synthesized using a hydrothermal method. Subsequently, an anion exchange reaction with TAA in an oil bath generated a Bi2S3 intermediate layer on the BiOCl surface, followed by the in situ growth of ZIS nanostructures, successfully constructing a BiOCl@Bi2S3@ZIS double Z-scheme heterojunction. By adjusting the amount of BiOCl, the interface contact and dispersion of the heterojunction were optimized. Characterization results demonstrate that the BiOCl@ZIS-25 heterojunction possesses the highest specific surface area (103.5 m2·g-1) and the most efficient charge separation. Under visible light irradiation, it achieved 97.88% degradation of methylene blue within 20 min, with a reaction rate constant 8 and 4 times higher than those of pure BiOCl and ZIS, respectively. Mechanistic investigations indicate that Bi2S3 interlayer acts as an electron-transfer bridge between BiOCl and ZIS, establishing a double Z-scheme charge transfer pathway that significantly enhanced the separation and utilization efficiency of photogenerated charge carriers. This study offers valuable insights for designing highly efficient and stable photocatalytic composite materials.