N-Doped Rutile Tio2 Nanorod@G-C3n4 Core/Shell S-Scheme Heterojunction for Boosting Photoreduction Co2 Activity

Rutile titanium dioxide (r-TiO2) is a booming photocatalyst because of its compact structure and good thermal stability. High carrier charge separation and strong redox ability of r-TiO2 are prerequisites for its photocatalytic CO2 reduction activity, which remains challenging. Here, a Step-scheme (S-scheme) heterojunction system consisting of nitrogen-doped rutile TiO2 (NT) nanorod and graphite carbon nitride (g-C3N4 , CN) were fabricated through an in situ deposition approach. NT nanorods were prepared through an ionothermal method using urea as a nitrogen source. Then g-C3N4 homogeneously grew on the surface of the TiO2 nanorods, forming an N-doped rutile TiO2@g-C3N4 (NT@CN) core/shell heterojunction. The as-synthesized heterojunction with 55 wt.% g-C3N4 presented the highest photoreduction CO2 activity (33.35 μmol/g for CO) without using additional cocatalysts or sacrifice reagents, which was 7.1 times higher than that of bare NT nanorods. The improvement of CO2 reduction activity could be credited to a large surface area and an impactful S-scheme heterostructure, which vested the catalyst with sufficient visible light harvesting, promoted segregation and transformation of photoinduced charge pairs, and enhanced the redox ability of carriers. Meanwhile, the NT@CN photocatalyst exhibited excellent reusability and stability. This work may assist in a new foresight to design and preparation of rutile TiO2-based S-scheme heterojunction with effectual CO2 reduction performance.