Flower-like Bi2S3-In2S3 heterojunction for efficient solar light induced photoreduction of Cr(VI).

To develop Bi2S3-based heterojunction for efficient solar light induced photoreduction of Cr(VI), flower-like Bi2S3-In2S3 composites consisted of nanorods were prepared via a microwave-assisted hydrothermal route. In contrast with pure Bi2S3, Bi2S3-In2S3 composites exhibited the enhanced photoreduction activity while the decreased adsorption capacity for Cr(VI) removal. The best removal efficiency of 70 mg L-1 Cr(VI) solution (99.86%) was achieved by the optimal 3-Bi2S3-In2S3 with a Bi/In molar ratio of 4:1 within 140 min. It's ascribed to the narrow band gap for strengthened visible-light response, the tight interface between Bi2S3 and In2S3 for rapid transfer and separation of charge carriers, and the enough S vacancies for highly-efficient active sites of adsorption-photoreduction. However, the long-term photo-corrosion resulted in the slightly inferior reusability of 3-Bi2S3-In2S3 under solar light irradiation after five cycles.