σ-π dative bond stabilizing copper active site drives CO₂ electrocatalysis to hydrocarbon.

Abstract

Copper-based catalysts are the premier choice for electrochemical reduction of CO₂ (CO₂RR) into hydrocarbons or oxygenates. However, the facilely structural reconstruction of copper sites during electrolysis poses significant challenges to the long-life electrolytic efficiency. Herein, we leverage the strong σ-π dative bonding between Cu^δ+ and alkyne-based ligands to stabilize copper sites for the prolonged CO₂RR. We demonstrate the feasibility of taming the electronic structures of copper sites through the tug of war between σ and π backbonding interactions. The optimal copper organic polymer with methoxy group functionalization (OMe-PhCu) exhibits a moderate charge density of copper sites and an intensified local asymmetric charge distribution of coordinative carbon, enhancing the selectivity of methane with a Faradaic efficiency of 68.8% and a partial current density of 324.5 mA cm^-2 in acidic electrolyte. In situ spectra and density functional theory calculations reveal enhanced *CO adsorption and lowered energy barrier for CO₂RR into methane over OMe-PhCu. Building upon such stable Cu^δ+ sites, we further construct Cu^δ+/Cu⁰ catalytic interfaces for the generally enhanced electrosynthesis of multi-carbons and ammonias. This synthetic chemistry paves the pathway for the design of stable catalytic active sites for renewable conversions.