N-doped rutile TiO nanorod@g-CN core/shell S-scheme heterojunctions for boosting CO photoreduction activity

The design of heterojunction photocatalysts is regarded as a very effective method to solve the high recombination rate of photogenerated charge carriers for CO 2 photoreduction into hydrocarbons, and interface engineering is urgently required to achieve high efficiency. Herein, graphitic carbon nitride (g-C 3 N 4 , CN) was uniformly grown on the surface of nitrogen-doped rutile TiO 2 (NT) nanorods by in situ deposition, and a NT@CN core/shell step-scheme (S-scheme) heterojunction system composed of NT nanorods and g-C 3 N 4 was synthesised. The as-synthesised heterojunction containing 55 wt% g-C 3 N 4 delivered the highest CO 2 photoreduction activity (33.35 μmol g −1 for CO) without additional cocatalysts or external sacrificial agents, which was 7.1 times higher than that of bare NT nanorods. This improved CO 2 reduction activity was attributable to the large surface area and impactful S-scheme heterostructure, which imparted the catalyst with sufficient visible-light harvesting ability, promoted the segregation and transformation of the photoinduced charge pairs, and enhanced the redox ability of the carriers. Concurrently, the NT@CN photocatalyst exhibited excellent reusability and stability. This work offers a new basis for designing and preparing rutile TiO 2 -based S-scheme heterojunctions with enhanced CO 2 reduction performance. A novel core/shell structure composed of N-doped rutile TiO 2 @g-C 3 N 4 (NT@CN x ) with an S-scheme heterojunction is successfully synthesized. The S-scheme heterojunction optimizes the electrochemical property and redox ability of the NT@CN x composite.