Nanoconfined Multi‐Scale Metal Catalysts: Confinement‐Induced Geometric, Electronic, and Microenvironment Regulation for Selective Multi‑Electron CO 2 Reduction

ABSTRACT The escalating levels of CO 2 emissions have intensified global climate challenges, and advancing the efficient conversion of CO 2 toward multi‐carbon products offers a potential solution to the energy dilemma. Electrochemical CO 2 reduction offers a promising solution but is hindered by sluggish kinetics, low selectivity, and poor catalyst stability. Nanoconfined metal catalysts have recently attracted significant attention due to their ability to precisely control active site structures, stabilize reactive intermediates, regulate local reaction environments, and tune electronic structure, effectively addressing these limitations. These unique confinement‐induced effects synergistically enhance catalytic activity, selectivity, and durability beyond the capabilities of conventional catalysts. This review systematically presents recent advances in multi‐scale metal catalysts, including metal atom, metal cluster, and metal nanoparticle catalysts, highlighting how confinement modulates geometric and electronic structures to optimize CO 2 adsorption, intermediate stabilization, and product selectivity. By integrating experimental and theoretical insights, this review elucidates key design principles and the mechanistic understanding of confinement‐induced superiorities. Furthermore, this review highlights existing challenges and proposes future directions for scalable synthesis strategies, precise regulation of local microenvironments, clarification of structure‐performance relationships, and pathways toward practical implementation. This comprehensive review provides a valuable framework for guiding the rational development of high‐performance nanoconfined electrocatalysts for CO 2 conversion.