Advances in Cu-based catalysts for electroreduction of CO2 to C2H4 in flow cells

Global investment in ethylene (C 2 H 4 ) production via nonpetroleum pathways is rising, highlighting its growing importance in the energy and environmental sectors. The electroreduction of carbon dioxide (CO 2 ) to C 2 H 4 in flow cells is emerging as a promising technology with broad practical applications. Direct delivery of gaseous CO 2 to the cathode catalyst layer overcomes mass transfer limitations, enhancing reaction rates and enabling high current density. This review summarizes recent research progress in the electrocatalytic CO 2 reduction reaction (eCO 2 RR) for selective C 2 H 4 production in flow cells. It outlines the principles of eCO 2 RR to C 2 H 4 and discusses the influence of copper-based catalyst morphology, crystal facet, oxidation state, surface modification strategy, and synergistic effects on catalytic performance. In addition, it highlights the compositional structure of the flow cell, and the selection and optimization of operating conditions, including gas diffusion electrodes, electrolytes, ion exchange membranes, and alternative anode reaction types beyond the oxygen evolution reaction. Finally, advances in machine learning are presented for accelerating catalyst screening and predicting dynamic changes in catalysts during reduction. This comprehensive review serves as a valuable reference for the development of efficient catalysts and the construction of electrolytic devices for the electrocatalytic reduction of CO 2 to C 2 H 4 . The synopsis of this review. It mainly includes the mechanism of electrocatalytic reduction of CO 2 to C 2 H 4 , the design strategies of catalyst, the selection and optimization of flow cell components, and applications of machine learning. • First comprehensive review focusing on CO 2 -to-C 2 H 4 conversion in flow cells, synthesizing developments since 2018 • Systematic analysis of Cu-based catalyst design strategies reveals key factors controlling C 2 H 4 selectivity in flow cells • Critical examination of flow cell components provides insights for addressing flooding and mass transport challenges • Integration of machine learning approaches offers new pathways for catalyst discovery and system optimization • Detailed roadmap for advancing CO 2 -to-C 2 H 4 conversion from laboratory to industrial implementation