Fabricating Oxygen Vacancy-Rich Bi2WO6/Bi2S3 Z-Scheme Nano-Heterojunction on Carbon Fiber with Polydopamine for Enhanced Photocatalytic Activity

The use of fibers or fabrics as frameworks for loading photocatalysts is beneficial in solving the problems of photocatalytic nanomaterials, which tend to agglomerate and are difficult to recycle. In this study, Bi2WO6/CFb and Bi2WO6/Bi2S3/CFb photocatalytic fibers rich in oxygen vacancies were prepared using carbon fibers as the framework by the crystal seed attachment method and in situ growth method by using the self-polymerization and strong adhesion properties of dopamine. The results of SEM, TEM and XRD tests showed that Bi2WO6 and Bi2WO6/Bi2S3 nanosheets were uniformly and completely encapsulated on the surface of the carbon fibers. The results of XPS and EPR tests showed that Bi2WO6 nanosheets were rich in oxygen vacancies. The PL, transient photocurrent responses and EIS results showed that the introduction of Bi2S3 significantly improved the migration efficiency of the photogenerated carriers of Bi2WO6/Bi2S3/CFb, which effectively hindered the recombination of photogenerated electron–hole pairs. By conducting degradation experiments on p-nitrophenol and analyzing the bandgap structure, it was postulated that the heterojunction structure of Bi2WO6/Bi2S3/CFb in the Bi2WO6/Bi2S3 material was not Type-II but Z-scheme. As analyzed by the active species assay, the active species that played a major role in the degradation process were O2− and h+. The incorporation of a small amount of Bi2S3 resulted in enhanced photocatalytic degradation activity of Bi2WO6/Bi2S3/CFb toward tetracycline hydrochloride compared to Bi2WO6/CFb. The excellent photocatalytic performance of Bi2WO6/Bi2S3/CFb photocatalytic fibers can be attributed to the rapid transmission and separation performance and the high oxidation and reduction capacities of photogenerated electron–hole pairs formed by direct Z-scheme heterojunctions.