Advances in high-performance continuous electrocatalytic reduction of CO₂ to carbon monoxide, ethylene, and methanol

Electrochemical CO₂ reduction (ECO₂R) has emerged as a promising approach to address the climate change, store renewable energy while closing the anthropogenic carbon cycle, and it is steadily maturing toward industrial implementation. Carbon monoxide (CO), a strategic precursor for a wide range of polymers and chemicals, along with ethylene (C₂H₄), notable for its high energy density, have been the dominant products in the most efficient electrolyzers. In addition, electrosynthesis of methanol (CH₃OH), a high-energy-density liquid fuel, has garnered significant interest as a sustainable alternative in the pursuit of a methanol economy. For industrial-scale application of ECO₂R, recent studies have focused on high-current-density evaluation of gas diffusion electrode (GDE)-based systems for the production of CO, C₂H₄, and CH₃OH. In the case of CO and C₂H₄, research primarily aims to improve energy efficiency, carbon efficiency, and system stability, while addressing operational challenges such as catalyst deactivation, salt precipitation, and electrode flooding. By contrast, methanol production systems are still striving to enhance Faradaic efficiency and current density. This review provides a unified discussion of highly efficient electrocatalytic systems for the continuous production of CO, C₂H₄, and CH₃OH, examining key aspects of process design. Furthermore, it presents a quantitative comparative assessment of system performance metrics, identifies emerging trends, and addresses existing challenges that warrant further investigation. Finally, the review outlines prospective directions for future research.