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-Cu_c/La₂O₃), achieving a high CH₄ Faradaic efficiency (FE_CH4) 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-Cu_c 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 Cu^δ+ (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.