Constructing Fe ⁴⁺ ‐N ₄ S Coordination via S ⁺ Ion Implantation for Highly Activating Photocatalytic CO ₂ RR

Although metal single atoms in photocatalysts can promote the CO 2 adsorption and reduction, it is still limited by the low valence state of metal single atoms. Here, S‐Fe single‐atom‐loaded (S‐Fe‐hCN) nanosheets are synthesized by spark plasma sintering (SPS) and following S + ion implantation. Benefiting from the mandatory nature of ion implantation technique, it not only reaches high content of S‐doping, but also forms a high valence state of Fe and a special metal single‐atom coordination structure, which greatly improves CO 2 RR performance, and achieves 1100 times enhancement in CO yield with high yield of 110 µmol g −1 h −1 , 100% CO selectivity, and a high quantum efficiency of 10.1% at 420 nm. EXAFS, in situ Mössbauer spectroscopy, and DFT calculations all reveal that S + ion implantation constructs a Fe 4+ ‐N 4 S coordination structure, leading to the high electron transfer, which builds a stable CO 2 ‐Fe‐N 4 S adsorption state, opens the C═O double bond, and activates the O atom.