Steering the Site Distance of Atomic Cu−Cu Pairs by First‐Shell Halogen Coordination Boosts CO₂‐to‐C₂ Selectivity

Abstract

Electrocatalytic reduction of CO2 into C2 products of high economic value provides a promising strategy to realize resourceful CO2 utilization. Rational design and construct dual sites to realize the CO protonation and C‐C coupling to unravel their structure‐performance correlation is of great significance in catalysing electrochemical CO2 reduction reactions. Herein, Cu‐Cu dual sites with different site distance coordinated by halogen at the first‐shell are constructed and shows a higher intramolecular electron redispersion and coordination symmetry configurations. The long‐range Cu‐Cu (Cu‐I‐Cu) dual sites show an enhanced Faraday efficiency of C2 products, up to 74.1%, and excellent stability. In addition, the linear relationships that the long‐range Cu‐Cu dual site is accelerated to C2H4 generation and short‐range Cu‐Cu (Cu‐Cl‐Cu) dual site is beneficial for C2H5OH formation are disclosed. In situ electrochemical attenuated total reflection surface enhanced infrared absorption spectroscopy, in situ Raman and theoretical calculations manifest that long‐range Cu‐Cu dual sites can weaken reaction energy barriers of CO hydrogenation and C‐C coupling, as well as accelerating deoxygenation of *CH2CHO. This study uncovers the exploitation of site‐distance‐dependent electrochemical property to steer the CO2 reduction pathway, as well as a potential generic tactic to target C2 synthesis by constructing the desired Cu‐Cu dual sites.