Ligand Protection Strategy for Highly Selective and Stable Electrochemical CO2 Methanation.

The large-scale electrochemical CO2 methanation represents a promising route toward carbon neutrality. The construction of efficient catalytic sites and the maintenance of the site stability are crucial to achieving high-efficiency conversion of CO2-to-CH4. Herein, we design a La2O3-supported oxygen-containing Cu clusters functionalized with hexanethiol (HT) molecules catalyst (HT@O-Cuc/La2O3), achieving a high CH4 Faradaic efficiency (FECH4) of 77.8% with a partial current density of 389.2 mA cm-2, and demonstrating excellent stability over a 250 h operation period. The thiol-ligand was modified at the interface between O-Cuc and La2O3 via S-coordination, enabling electron transfer between La and Cu sites and establishing a stable electronic supplementary channel that continuously stabilizes the low-coordinated Cuδ+ (0.4 < δ < 0.5) active state during the electrochemical process. Moreover, mechanistic studies reveal that the ligand modification optimizes *CO adsorption on Cu sites and steers *CHO hydrogenation toward *CH2OH. The electronic channel effect can strengthen the bond energy of Cu-C, facilitating the desorption of *OH. The La-mediated water activation generates abundant protons, which drives the *CH2─*CH3─*CH4 directional hydrogenation step, ultimately achieving highly selective CH4 production.