Advancing CO 2 Electroreduction Toward Multicarbon Products via Catalyst Engineering and Integrated Paired Electrolysis

Electrochemical carbon dioxide reduction (CO 2 RR) provides a compelling pathway for converting CO 2 into value‐added multicarbon (C 2+ ) products using renewable electricity, yet its technological translation remains limited by coupled challenges spanning catalyst chemistry, reaction microenvironments, reactor architecture, and cathode‐anode integration. This review develops a multiscale framework that connects molecular‐level C‐C coupling with device‐ and process‐level performance. Fundamental CO 2 activation, reaction pathways, electrochemical metrics, and structure–activity relationships are critically examined, with particular emphasis on Cu‐based catalysts and emerging catalyst‐engineering strategies for selective C 2+ synthesis. These catalytic principles are then linked to operando surface states, intermediate coverage, local microenvironments, mass transport, membrane behavior, and electrolyzer configuration under technologically relevant conditions. Beyond cathodic optimization, oxygen evolution and alternative anodic chemistries, including biomass‐derived alcohol oxidation and plastic‐derived stream valorization, are assessed within integrated paired‐electrolysis architectures. Their practical significance is benchmarked through matched current density, full‐cell voltage, carbon and electron efficiency, product concentration, crossover, separation, durability, and realistic feed compatibility. This framework exposes critical catalyst‐reactor‐process trade‐offs and defines design principles for scalable, durable, and economically credible CO 2 ‐to‐C 2+ electrosynthesis.