Bismuth MOF-Derived BiOI/Bi₅O₇I p-n Heterojunctions with Enhanced Charge Separation and Visible-Light Photocatalytic Performance

Given the environmental hazards posed by low-concentration NOx emissions, visible-light-driven photocatalytic technologies have been widely studied for the removal of NOx. Constrained by the insufficient light absorption range and rapid recombination of carriers of an individual photocatalyst, the construction of heterojunctions has emerged as a promising strategy to bolster photocatalytic reaction kinetics. However, traditional approaches for fabricating heterojunctions frequently result in interfaces that are loosely connected and poorly contacted, greatly limiting the photocatalytic performance of the heterojunctions. Therefore, in this research, a BiOI/Bi5O7I p-n heterojunction was successfully constructed through an in situ phase transformation approach, demonstrating exceptional photocatalytic performance in the purification of NO under visible light irradiation. Benefiting from the interfacial electric field formed at the tightly formed heterojunction interface, significant suppression of carrier recombination and improved separation efficiency were achieved, as evidenced by both in situ DRIFTS and theoretical calculations. This strategy can also inspire the utilization of in situ heterojunction construction to modulate the electronic structure of conventional bismuth-based semiconductors, enhance charge transfer at the interface, and improve the photocatalytic activity.