Highly active Cs2SnCl6/C3N4 heterojunction photocatalysts operating via interfacial charge transfer mechanism

In this study, a novel lead-free perovskite heterojunction Cs2SnCl6/C3N4 composite was constructed and applied for photocatalytic NO purification. After design optimization, the Cs2SnCl6/C3N4 heterojunction exhibit excellent and stable photocatalytic NO purification ability under visible-light irradiation, which is significantly better than pristine Cs2SnCl6 and C3N4. Combined in-situ DRIFTS and electron spin resonance spin-trapping, the mechanism of Cs2SnCl6/C3N4 photocatalytic NO removal was revealed. Under visible-light irradiation, the photo-generated electrons on the conduction band of C3N4 would spontaneously migrate to the CB of Cs2SnCl6, leaving holes (h+) on the valence band of C3N4, contributing to efficiently segregated charge carriers and improved photocatalytic NO purification. Density functional theory calculations also revealed the directional electron transfer at the C3N4 and Cs2SnCl6 interface, in which the charge was migrated from C3N4 to Cs2SnCl6 induced by the internal electric field. This research sheds fresh light on the fabrication of Cs2SnCl6/C3N4 heterojunctions as well as its effective interfacial charge separation.