Graphitic carbon nitride/La, Rh co-doped SrTiO3 S-scheme heterojunction for photocatalytic CO2 reduction

Photocatalytic reduction of CO 2 has attracted considerable interest owing to its potential to resolve the energy and environmental problems. Nevertheless, the lack of proficient photocatalysts has restricted the application of solar-driven photocatalytic CO 2 reduction. Herein, we reported an S-scheme heterojunction by combining g-C 3 N 4 with La 3+ and Rh 3+ co-doped SrTiO 3 through the electrostatic self-assembly method for the efficient photocatalytic CO 2 reduction. In comparison with g-C 3 N 4 , the as-prepared CN/LRSTO-30 wt% S-scheme heterojunction not only possesses a broadened visible-light response due to the defect states in La, Rh co-doped SrTiO 3 induced by co-doped La 3+ and Rh 3+ but also has more adsorption sites for the capture and activation of CO 2 molecules. Additionally, separation and transfer efficiency of the photoinduced charge carriers is much enhanced in the CN/LRSTO-30 wt% S-scheme heterojunction via its robust internal electric field, which is firmly demonstrated by in situ irradiation X-ray photoelectron spectroscopy technology. Consequently, the prepared S-scheme heterojunction achieves impressive photocatalytic CO 2 reduction performance with an average CO and CH 4 evolution rate of 4.1–1.8 μmol·g −1 ·h −1 , respectively, which are ~ 1.9 and  ~ 22.5-fold higher than those of pure g-C 3 N 4 . This study provides innovative perspectives on the design of creative S-scheme heterojunctions for applications in photocatalytic CO 2 reduction. Graphical abstract