Corn-straw-derived, pyridine-nitrogen-rich NCQDs modified Cu0.05Zn2.95In2S6 promoted directional electrons transfer and boosted adsorption and activation of CO2 for efficient photocatalytic reduction of CO2 to CO

In this study, biomass-derived carbon quantum dots (CQDs) doped with different nitrogen sources were loaded on Cu 0.05 Zn 2.95 In 2 S 6 (CZIS) to achieve efficient and highly selective CO 2 photocatalytic reduction. Results of various characterizations demonstrated that CZIS@CQDs-T with the highest pyridine nitrogen content (30.4%) exhibited the best light utilization, the most efficient carriers’ separation. In-situ XPS demonstrated that NCQDs were conducive to promoting electron transferred directly from the Zn 3 In 2 S 6 to NCQDs under light illumination. The CZIS@CQDs-T achieved a CO yield of 70.691 μmol·g −1 ·h −1 with selectivity of 100%, and the yield was 4.77 times higher than that of the CZIS. CO 2 -TPD showed that the CZIS@CQDs-T displayed the strongest adsorption capacity for CO 2 , and a weak adsorption capacity for CO. In-situ FTIR analysis showed COOH* was the key intermediates during CO 2 photoreduction process. DFT calculation revealed that the limb-joined pyridine nitrogen of the CZIS had denser charge density when adsorbing CO 2 , and the adsorption energy of CO 2 and desorption energy of CO were significantly enhanced compared with the CZIS. Based on the above analysis, possible pathways and mechanisms of CO 2 reduction were inferred. This study provides inspiration for designing efficient photocatalysts for highly selective reduction of CO 2 .