High-efficiency photocatalytic CO reduction enabled by interfacial Ov and isolated Ti of g-CN/TiO 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 was precisely regulated at the interface of g-CN/TiO Z-scheme heterojunction (g-CN/Ov-Ti-TiO) by optimizing the opening degree of the calcination system, showing excellent production rate of CO and CH from CO photoreduction under visible light. This photocatalytic system also exhibited prominent stability. Combining theoretical calculation and characterization, the introduction of Ov and isolated Ti 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 CO bonds to promote the activation of adsorbed inert CO molecules, significantly reducing the energy barrier of the rate-limiting step during CO reduction. This work demonstrates the great application potential of reasonably regulating heterojunction interface for efficient photocatalytic CO reduction.