N-doped rutile TiO2 nanorod@g-C3N4 core/shell S-scheme heterojunctions for boosting CO2 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 CO2 photoreduction into hydrocarbons, and interface engineering is urgently required to achieve high efficiency. Herein, graphitic carbon nitride (g-C3N4, CN) was uniformly grown on the surface of nitrogen-doped rutile TiO2 (NT) nanorods by in situ deposition, and a NT@CN core/shell step-scheme (S-scheme) heterojunction system composed of NT nanorods and g-C3N4 was synthesised. The as-synthesised heterojunction containing 55 wt% g-C3N4 delivered the highest CO2 photoreduction activity (33.35 mu mol 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 CO2 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 TiO2-based S-scheme heterojunctions with enhanced CO2 reduction performance.

Automated summary

The synthesis of NT@CN core/shell structure S-scheme heterojunction photocatalyst was achieved by uniformly growing graphitic carbon nitride (g-C3N4) on the surface of nitrogen-doped rutile TiO2 (NT) nanorods. The as-synthesized heterojunction with 55 wt% g-C3N4 showed the highest CO2 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 improvement was attributed to the large surface area and impactful S-scheme heterostructure, enabling sufficient visible-light harvesting ability, segregation and transformation of charge pairs, and enhanced redox ability of carriers. Furthermore, the NT@CN photocatalyst displayed excellent reusability and stability. This work provides a new foundation for designing and preparing rutile TiO2-based S-scheme heterojunctions with enhanced CO2 reduction performance.