In-situ topotactic construction of novel rod-like Bi2S3/Bi5O7I p-n heterojunctions with highly enhanced photocatalytic activities

In this work, a novel Bi2S3/Bi5O7I p-n heterojunction with three-dimensional rod-like nanostructure was successfully constructed through an in-situ topotactic ion exchange approach. A possible evolution mechanism from Bi5O7I nanobelts (NBs) into Bi2S3/Bi5O7I rod-like heterostructures (BSI RHs) was proposed, depicting the self-assembly process of internal Bi5O7I NBs and outside networks interwoven by Bi2S3 nanorods (NRs), which abided by the Ostwald ripening and epitaxial growth. Owing to the formation of p-n heterojunction and rich oxygen vacancies (OVs), the visible-light absorption ability and separation of photogenerated charge carriers of BSI RHs were highly promoted, leading to a greatly improved photocatalytic ability than that of Bi2S3 and Bi5O7I. BSI-1 exhibited the strongest photocatalytic performance, and almost all rhodamine B (RhB) and Pseudomonas aeruginosa (P. aeruginosa) can be thoroughly removed within 90 min. Moreover, a possible photocatalytic mechanism of BSI RHs was proposed based on the tests of active species trapping, electron spin resonance (ESR), photoelectrochemistry (PEC), and photoluminescence (PL) combined with the density functional theory (DFT) simulated computation, validating the dominating roles of · O2− and h+ during the photocatalytic process. This work is expected to motivate further efforts for developing novel heterostructures with highly efficient photocatalytic performances, which presents a promising application prospect in the fields of energy and environment.