High-efficiency photocatalytic CO2 reduction enabled by interfacial Ov and isolated Ti3+ of g-C3N4/TiO2 Z-scheme heterojunction

Exploring the real force that drives the separation of Coulomb-bound electron-hole pairs in the interface of heterojunction photocatalysts can establish a clear mechanism for efficient solar energy conversion efficiency. Herein, the formation of oxygen vacancy (Ov) and isolated Ti 3+ was precisely regulated at the interface of g-C 3 N 4 /TiO 2 Z-scheme heterojunction (g-C 3 N 4 /Ov-Ti 3+ -TiO 2 ) by optimizing the opening degree of the calcination system, showing excellent production rate of CO and CH 4 from CO 2 photoreduction under visible light. This photocatalytic system also exhibited prominent stability. Combining theoretical calculation and characterization, the introduction of Ov and isolated Ti 3+ on the interface could construct a charge transfer channel to break the forbidden transition of n → π*, improving the separation process of photoexcited electron-hole pairs. The photoexcited electrons weakened the covalent interaction of C O bonds to promote the activation of adsorbed inert CO 2 molecules, significantly reducing the energy barrier of the rate-limiting step during CO 2 reduction. This work demonstrates the great application potential of reasonably regulating heterojunction interface for efficient photocatalytic CO 2 reduction.