Advances in Electrochemical CO ₂ Reduction: A Review and Perspective on Structure–Performance Relationships

Electrochemical CO 2 reduction (eCO 2 RR) offers a promising pathway to convert greenhouse gas emissions into value-added fuels and chemicals, supporting climate mitigation and a circular carbon economy. This review critically examines recent advances in catalyst design and electrolyzer engineering, with an emphasis on structure–mechanism–performance relationships governing activity, selectivity, and stability. Silver and gold catalysts enable near-unity CO selectivity; bismuth- and tin-based systems favor formate via stabilized *OCHO intermediates, while copper uniquely facilitates C–C coupling toward multicarbon hydrocarbons and alcohols through *CO adsorption, dimerization, and proton-coupled electron transfer pathways. Density functional theory (DFT) studies, including Gibbs free energy analyses and charge-transfer insights, are integrated to elucidate the reaction mechanisms, facet effects, defect chemistry, and tandem catalysis. Beyond intrinsic catalyst properties, the review highlights the critical roles of local reaction microenvironments, membrane catalyst interfaces, ion transport, and reactor architectures in achieving industrially relevant current densities and durability. Emerging high-throughput DFT and machine-learning-assisted screening strategies are discussed as accelerators for rational catalyst discovery. This work provides a mechanistically grounded roadmap bridging atomic-scale catalyst design with system-level performance, outlining key challenges and opportunities for scalable, energy-efficient electrochemical CO 2 conversion.