Improving CO2 photoconversion with ionic liquid and Co single atoms

Abstract Photocatalytic CO 2 conversion promises an ideal route to store solar energy into chemical bonds. However, sluggish electron kinetics and unfavorable product selectivity remain unresolved challenges. Here, an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and borate-anchored Co single atoms were separately loaded on ultrathin g-C 3 N 4 nanosheets. The optimized nanocomposite photocatalyst produces CO and CH 4 from CO 2 and water under UV–vis light irradiation, exhibiting a 42-fold photoactivity enhancement compared with g-C 3 N 4 and nearly 100% selectivity towards CO 2 reduction. Experimental and theoretical results reveal that the ionic liquid extracts electrons and facilitates CO 2 reduction, whereas Co single atoms trap holes and catalyze water oxidation. More importantly, the maximum electron transfer efficiency for CO 2 photoreduction, as measured with in-situ μs-transient absorption spectroscopy, is found to be 35.3%, owing to the combined effect of the ionic liquid and Co single atoms. This work offers a feasible strategy for efficiently converting CO 2 to valuable chemicals.