Nitrogen-Adsorbed Hydrogen Species Promote CO₂ Methanation on Cu Single-Atom Electrocatalyst

Cu single-atom catalysts are considered as efficient candidates to boost the electrocatalytic CO2 reduction to CH4, but the source of *H species for the CH4 formation during the multiple electron–proton transfer process is still elusive. Herein, we reported a facile strategy for the large-scale preparation of Cu single-atom catalysts via a solid-state pyrolysis strategy, with a Cu content of 3.86 wt %. The Cu single atoms were coordinated by four nitrogen atoms, which allowed to accelerate water dissociation to form *H species and stabilize key intermediates toward CH4. The Cu single-atom catalyst exhibited an excellent CO2-to-CH4 electroreduction performance, including a Faradaic efficiency of 68.2%, a high partial current density of 493.1 mA cm–2, and a good electrochemical stability. This work suggests a potential means of the mass production of Cu single-atom catalysts, with understanding of the mechanism of the CO2 electroreduction to CH4.