Spatially confined iron single-atom and potassium ion in carbon nitride toward efficient CO2 reduction

Artificial photosynthesis is a promising strategy for converting CO2 and H2O into fuels and value-added products, while the low catalytic efficiency greatly restricts its practical applications. Herein, we demonstrated that graphitic carbon nitride with spatially confined Fe single-atom and potassium ion (FeN4/K-g-C3N4) exhibited the high activity and selectivity for photocatalytic CO2 reduction. Specifically, the conversion rates of CO2 into CO could achieve up to 20.00 mu mol g(-1) h(-1) with nearly 100% selectivity, more than 10 times higher performances than pristine g-C3N4. Comprehensive characterizations and theoretical calculations revealed that the single-atom Fe bonded with four N atoms in g-C3N4 intralayer, which serve as the active center for absorption and activation of CO2 molecules. The alkali K ions inserted the g-C3N4 interlayers owing to their suitable diameters, which could effectively promote charge separation and transfer. Synergizing the spatial confinements of Fe single-atoms and K ions in g-C3N4 remarkably promoted the photocatalytic activity and selectivity for CO2 reduction into CO.