Optimization strategies for carbon dioxide electroreduction to ethylene

Abstract

The electrochemical reduction of CO₂ into value-added hydrocarbons represents a promising approach towards achieving a closed-loop carbon cycle. However, the intricacies of the electrochemical carbon dioxide reduction reaction (ECO₂RR) mechanisms and the presence of competitive hydrogen evolution reaction (HER) pose significant limitations to the selectivity, especially for C₂₊ products. To promote the research on the electroreduction of CO₂ to C₂H₄, we start with the impact of intrinsic factors including electrolytes (aqueous electrolytes, organic electrolytes and ionic liquids), electrodes (gas diffusion electrodes, GDEs), and electrolyzers (flow cells, membrane electrode assembly (MEA) cells, and solid-state electrolyte (SSE) cells), as well as extrinsic factors such as reaction temperature and pressure, on the mass transfer and catalytic performance. Then, structural adjustment strategies to optimize CO₂RR catalysts are provided. Subsequently, we combine in-situ characterization techniques with theoretical calculations to track key intermediates, monitor structural evolution and elaborate the reaction mechanisms profoundly. Additionally, the recent advancements in Cu-based and non-Cu-based catalysts for the reduction of CO₂ to C₂H₄ are discussed. Finally, the challenges in the practical application of CO₂ electroreduction to C₂H₄ are proposed, and the future research direction is expected.