Electrochemical Carbon Dioxide Reduction to Ethylene: From Mechanistic Understanding to Catalyst Surface Engineering

Electrochemical carbon dioxide reduction reaction (CO₂RR) provides a promising way to convert CO₂ to chemicals. The multicarbon (C₂₊) products, especially ethylene, are of great interest due to their versatile industrial applications. However, selectively reducing CO₂ to ethylene is still challenging as the additional energy required for the C-C coupling step results in large overpotential and many competing products. Nonetheless, mechanistic understanding of the key steps and preferred reaction pathways/conditions, as well as rational design of novel catalysts for ethylene production have been regarded as promising approaches to achieving the highly efficient and selective CO₂RR. In this review, we first illustrate the key steps for CO₂RR to ethylene (e.g., CO₂ adsorption/activation, formation of *CO intermediate, C-C coupling step), offering mechanistic understanding of CO₂RR conversion to ethylene. Then the alternative reaction pathways and conditions for the formation of ethylene and competitive products (C₁ and other C₂₊ products) are investigated, guiding the further design and development of preferred conditions for ethylene generation. Engineering strategies of Cu-based catalysts for CO₂RR-ethylene are further summarized, and the correlations of reaction mechanism/pathways, engineering strategies and selectivity are elaborated. Finally, major challenges and perspectives in the research area of CO₂RR are proposed for future development and practical applications.