Fabrication of an S-Scheme AgBr-PI Heterojunction for Biphenyl A Degradation and Its Degradation Pathways and Mechanism

Step-like-scheme (S-scheme) heterojunctions have demonstrated their superiority in regulating the directional migration of photo-generated carriers for artificial photosynthesis. However, adjusting the S-scheme charge transfer at the nanostructure interface of the heterostructure is a big challenge. Herein, a novel S-scheme AgBr-polyimide (PI) heterojunction was prepared by in situ deposition of AgBr nanoparticles on polyimide conjugated polymer, which was employed as a base material to anchor AgBr nanoparticles via nitrogen-metal bonds. The optimized AgBr-PI sample, coupling 50 wt % AgBr with PI, shows the highest photocatalytic activity, which could completely remove 10 ppm biphenyl A (BPA) within 15 min under simulated solar visible light. The improvement of the photocatalytic performance was attributed to the valid S-scheme charge transfer mode through building strong interfacial interaction between AgBr and PI, which accelerated the charge separation and retained strong redox abilities. At the same time, the S-scheme charge transfer mechanism is confirmed by electron paramagnetic resonance and in situ irradiated X-ray photoelectron spectroscopy.