<p>CO₂ electroreduction (CO₂RR) represents a promising negative-carbon technology, which is in urgent need for efficient and high-selectivity catalysts. Here, a support control strategy is employed for precise surface engineering of charge-asymmetry nanocluster catalyst (CuZnSCN), in which zinc and copper atoms together form a metal cluster loaded on sulfur and nitrogen co-etched carbon matrix. The synergistic promotion mechanism of CO₂RR by Cu–Zn atom interactions and sulfur–nitrogen atom doping was investigated. A CO partial current density of 74.1&#xa0;mA&#xa0;cm⁻² was achieved in an alkaline electrolyte, as well as a considerable CO Faraday efficiency of 97.7%. In situ XAS (X-ray absorption spectroscopy) showed that the stabilization of Cu⁺ and Zn²⁺ species in the nanoclusters and doped sulfur atoms during the CO₂RR process contributes to the sustained adsorption of protons and the generation and conversion of the CO. This work verifies the possibility of metal-support and intermetallic interactions to synergistically enhance electrochemical catalytic performance and provides ideas for further bimetallic cluster catalyst development.</p> Graphical abstract <p></p>