Coordination Reconstruction of Fe Single Atoms by Encapsulated Nickel Nanoparticles for Efficient CO2 Electroreduction

Coordination reconstruction of atomically dispersed active sites in electrocatalytic reactions is expected to enhance the catalytic activity, but achieving this goal remains challenging. Herein, a single-atom‒nanoparticle synergistic catalyst composed of pyridine Fe─N sites and Ni nanoparticles (NPs) encapsulated in nitrogen-doped carbon nanotubes is presented, in which the Ni NPs can reconstruct the Fe─N─C coordination structure from Fe─N 4 to Fe─N 2 through the carbon nanotube structure during the CO 2 electroreduction reaction. The catalyst exhibites a low onset potential of −0.12 V in an alkaline flow cell, with a high Faradaic efficiency for CO (FE CO ) greater than 97% over a wide potential range of −0.4–−1.2 V and a maximum FE CO of 98.7%. In situ X-ray absorption spectroscopy and infrared characterization results demonstrate that the reduction in the Fe─N coordination number during the reaction process promotes the protonation of CO 2 to form the * COOH intermediate and thereby significantly improves the CO 2 electroreduction performance.