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

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 sites are accelerated to C2H4 generation and short‐range Cu−Cu (Cu−Cl−Cu) dual sites are 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 properties 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. The atomic Cu−Cu pairs with a controllable site distance by first‐shell halogen coordination was reported in this work, which shows an enhanced CO2RR performance of C2 products. In addition, a linear scaling relationship that that long‐range Cu−Cu (Cu−I−Cu) dual sites is accelerated to C2H4 generation, while short‐range Cu−Cu (Cu−Cl−Cu) dual sites is beneficial for C2H5OH formation was revealed to give a wide comprehension towards site‐distance‐dependent catalytic performance.