Surface Behavior Regulation of Intermediates on the Copper-Based Catalysts for Enhancing Electrocatalytic CO2 Reduction to Ethylene.

Electrocatalytic CO2 reduction (CO2RR) on copper-based catalysts uniquely enables C─C coupling to produce multi-carbon products such as ethylene and ethanol, owing to their moderate binding affinity toward key intermediates (*CO, *H). However, industrial application is hindered by structural instability, imprecise active-site control, complex product distributions, and competing side reactions. Such structural strategies include facet engineering, defect creation, oxidation-state modulation, and interface engineering, which have improved selectivity, yet most focus on static structure-performance relationships, overlooking dynamic surface behaviors of intermediates. This review builds a mechanism-centered framework along the CO2RR pathway (CO2 activation, *CO enrichment, *CO dimerization) to elucidate how adsorption configuration, spatial distribution, coverage dynamics, and transformation kinetics of intermediates govern selectivity, providing both theoretical guidance and practical strategies for the development of next-generation Cu-based CO2RR systems with enhanced selectivity, durability, and industrial applicability.