Electron Localization-Triggered Proton Pumping Toward Cu Single Atoms for Electrochemical CO Methanation of Unprecedented Selectivity.

Slow multi-proton coupled electron transfer kinetics and unexpected desorption of intermediates severely hinder the selectivity of CO methanation. In this work, a one-stone-two-bird strategy of pumping protons and improving adsorption configuration/capability enabled by electron localization is developed to be highly efficient for CH electrosynthesis over Cu single atoms anchored on bismuth vacancies of BiVO (BiVO─Cu), with superior kinetic isotope effect and high CH Faraday efficiency (92%), far outperforming state-of-the-art electrocatalysts for CO methanation. Control experiments and theoretical calculations reveal that the bismuth vacancies (V) not only act as active sites for HO dissociation but also induce electron transfer toward Cu single-atom sites. The V-induced electron localization pumps *H from V sites to Cu single atoms, significantly promoting the generation and stabilization of the pivotal intermediate (*CHO) for highly selective CH electrosynthesis. The metal vacancies as new initiators show enormous potential in the proton transfer-involved hydrogenative conversion processes.