Molecular Modification Strategies for CO ₂ Electroreduction to C ₂₊ Products: Classifications, Mechanisms, Advances, and Perspectives

CO 2 electroreduction (CO 2 ER) into value‐added multicarbon (C 2+ ) products represents a compelling strategy for renewable energy storage and anthropogenic carbon recycling. However, conventional inorganic catalysts are often hindered by sluggish kinetics, poor product selectivity, and the severely competitive hydrogen evolution reaction (HER). Recently, tailoring the catalyst–microenvironment interface via organic molecular modification has emerged as a robust approach to circumvent these bottlenecks. This review systematically summarizes recent progress in such molecular engineering for CO 2 ER toward C 2+ products. Firstly, the key molecular modifiers, including functional small molecules, ionic modifiers, macrocyclic and supramolecular compounds, polymers, and framework materials, are classified and systematically compared. Next, the fundamental mechanisms underlying performance enhancements are elucidated, including the modulation of the metal electronic structure, regulation of the local microenvironment, spatial confinement of reaction intermediates, and facilitation of tandem catalysis. Further discussion dissects how these modifications thermodynamically and kinetically steer the C 2+ pathway by promoting CO 2 activation and C–C coupling while suppressing HER. Finally, remaining challenges and future directions are addressed. This review aims to provide a clear and comprehensive guide for the rational design of highly efficient, molecularly modified CO 2 ER catalysts.