Sulfur Vacancy Engineering of Coralloidal Bi2S3@In2S3 Heterojunction for Enhanced Photocatalytic Removal of Cr(VI)/Antibiotic Mixed Pollutants

Defects can tune the band structure of semiconductors, thereby reconfiguring the corresponding heterojunctions. In this study, coralloidal Bi 2 S 3 @In 2 S 3 heterostructures rich in sulfur vacancies were successfully developed via a one-step hydrothermal method with content regulation of the sulfur source. In 2 S 3 nanosheets are evenly distributed along Bi 2 S 3 nanorod clusters, imparting a unique coralloidal structure and compact interfacial contact that accelerates the transportation of photoinduced electrons and holes. Moreover, the sulfur vacancy strengthens the light absorption and enables staggered energy band alignment for Bi 2 S 3 @In 2 S 3 heterostructures, which further promotes charge carrier separation. Owing to these favorable features, the coralloidal Bi 2 S 3 @In 2 S 3 heterostructure with rich sulfur vacancies exhibited a high photocatalytic efficiency for Cr(VI) reduction, whose reaction rate constant is 34.9, 8.1 and 1.9-fold enhancements compared with those of Bi 2 S 3 , In 2 S 3 , and the Bi 2 S 3 @In 2 S 3 heterostructure with poor sulfur vacancies, respectively. For simultaneous Cr(VI) reduction and antibiotic (tetracycline and ciprofloxacin) degradation under visible light, the excellent Cr(VI) reduction performance was kept and the degradation rates of the antibiotics clearly increased (more than 25%) compared with those of the reactions in the corresponding solo system, which was due to the synergistic effect of efficient utilization of photoinduced electrons and holes. This article provides valuable insight and guidance for the design of defective heterostructures and the treatment of complex water pollutants.