Coordination reconstruction of atomically dispersed active sites in electrocatalytic reactions is expected to enhance the catalytic activity, but achieving this goal remains challenging. Herein, we present a single-atom‒nanoparticle synergistic catalyst composed of pyridine Fe‒N sites and Ni nanoparticles (NPs) encapsulated in nitrogen-doped carbon nanotubes, in which the Ni NPs can reconstruct the Fe‒N‒C coordination structure from Fe‒N4 to Fe‒N2 through the carbon nanotube structure during the CO2 electroreduction reaction. The catalyst exhibited a low onset potential of −0.12 V in an alkaline flow cell, with a high Faradaic efficiency for CO (FECO) greater than 97% over a wide potential range of −0.4 to −1.2 V and a maximum FECO of 98.7%. In-situ X-ray absorption spectroscopy and infrared characterization results demonstrated that the reduction in the Fe‒N coordination number during the reaction process promoted the protonation of CO2 to form the *COOH intermediate and thereby significantly improved the CO2 electroreduction performance.
