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

Artificial photosynthesis is a promising strategy for converting CO 2 and H 2 O 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 (FeN 4 /K-g-C 3 N 4 ) exhibited the high activity and selectivity for photocatalytic CO 2 reduction. Specifically, the conversion rates of CO 2 into CO could achieve up to 20.00 μmol g −1 h −1 with nearly 100% selectivity, more than 10 times higher performances than pristine g-C 3 N 4 . Comprehensive characterizations and theoretical calculations revealed that the single-atom Fe bonded with four N atoms in g-C 3 N 4 intralayer, which serve as the active center for absorption and activation of CO 2 molecules. The alkali K ions inserted the g-C 3 N 4 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-C 3 N 4 remarkably promoted the photocatalytic activity and selectivity for CO 2 reduction into CO. Spatially confined iron single-atom (intralayer) and potassium (interlayer) ion could remarkably promote both activity and selectivity of g-C 3 N 4 for photocatalytic CO 2 reduction into CO. • One-step molten-salt-assisted route was developed for fabricating dual-spatially confined Fe single-atom and K + ion in C 3 N 4 . • The single-atom Fe acted as active center for significantly promoting CO 2 absorption and conversion. • The intercalated K ions remarkably promoted charge transfer between adjacent layers in C 3 N 4 . • The photocatalytic CO 2 reduction activity and selectivity have been significantly enhanced.