Abstract
Electrocatalytic reduction of CO(2) to fuels and chemicals represents a promising pathway for CO(2) utilization and energy conversion. However, metal-based catalysts often suffer from diminished selectivity in the direct reduction of CO(2) to acetate due to suboptimal intermediate adsorption energy imposed by the linear scaling relationship of d-band theory. We describe a deposition-etching strategy that tunes the sp(2)/sp(3) hybridization of carbon in diamond to tune the adsorption equilibrium of intermediates for CO(2) reduction to acetate, which circumvents the constraints of the d-band electrons. This metal-free catalyst achieves a Faradaic efficiency of 62.7% for CO(2)-to-acetate conversion and demonstrated 100 hours durability. Mechanistic studies reveal that introducing sp(2)-carbons into the sp(3)-carbon matrix can control the adsorption energies of *CO(2) and *CO. The sp(2)/sp(3)-carbon active sites facilitate the formation of the *CHO intermediate, which is asymmetrically coupled with the *CO(L) to generate acetate.