Local compressive strain regulation of atomically dispersed NiN4 sites for enhancing CO2 electroreduction to CO

Electroreduction of CO₂ to valuable chemicals powered by renewable electricity provides a sustainable approach to reduce the environmental issues originating from CO₂ emission. However, insufficient current density and production selectivity hinder its further application. In this case, precisely regulating the CO₂ reduction reaction (CO₂RR) active sites is an excellent strategy to simultaneously reduce the reaction barrier and suppress the hydrogen evolution reaction (HER) pathway. Herein, the strain regulation of atomically dispersed NiN₄ active sites is investigated in helical carbon. Ni-N coordination in the curved carbon lattice displays a reduced distance compared to that in a straight lattice, inflicting local compressive strain on NiN₄. The resultant catalyst shows the highest CO selectivity of up to 99.4% at -1.4 V (vs. RHE), the FE_CO is maintained at over 85% over a wide potential range from -0.8 to -1.8 V (vs. RHE), and the maximum partial current density for CO reaches a high of 458 mA cm^-2 at -1.8 V (vs. RHE). Theoretical investigations show the superior CO₂ electroreduction performance of curved NiN₄ stems from its remarkable ability to generate the *COOH intermediate and to suppress the hydrogen combination simultaneously. Our findings offer a novel strategy to rationally regulate the local three-dimensional structure of single-atom sites for efficient electrocatalysis.