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

Abstract Electrochemical carbon dioxide reduction reaction (CO 2 RR) provides a promising way to convert CO 2 to chemicals. The multicarbon (C 2+ ) products, especially ethylene, are of great interest due to their versatile industrial applications. However, selectively reducing CO 2 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 CO 2 RR. In this review, we first illustrate the key steps for CO 2 RR to ethylene ( e.g. , CO 2 adsorption/activation, formation of *CO intermediate, C–C coupling step), offering mechanistic understanding of CO 2 RR conversion to ethylene. Then the alternative reaction pathways and conditions for the formation of ethylene and competitive products (C 1 and other C 2+ products) are investigated, guiding the further design and development of preferred conditions for ethylene generation. Engineering strategies of Cu-based catalysts for CO 2 RR-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 CO 2 RR are proposed for future development and practical applications.