The carbon dioxide reduction reaction (CO₂RR) is a promising strategy for converting CO₂ into high-value chemicals. However, the rational design of efficient catalysts for steering product selectivity toward specific high-value chemicals continues to be a central goal in electrocatalysis research. Recently, nanoporous confined electrocatalysts have garnered attention due to their unique pore structures, which not only increase the accessibility and utilization of active sites but also promote the enrichment and stabilization of key reaction intermediates and modulate the local reaction microenvironment. These combined effects contribute to improved reaction kinetics and enhanced product selectivity. This review systematically summarizes the mechanistic foundations of nanoporous confinement in CO₂RR, emphasizing its role in governing reaction pathways and selectivity. We introduce the fundamental design principles of nanoporous confined electrocatalysts, detailing how their pore size, tortuosity, and connectivity influence CO₂ diffusion, local concentration gradients, and electrolyte accessibility. Then highlight how confinement-induced spatial regulation facilitates intermediate accumulation, directional proton transfer, and local pH modulation, collectively steering product selectivity toward desired C₁ and multi-carbon (C₂₊) products. Representative material systems and structure–performance relationships are discussed to illustrate these effects. Finally, we summarize the current challenges in mechanistic understanding and practical implementation, and propose future directions for developing nanoporous systems that integrate controlled transport, catalytic reactivity, and system-level scalability.

Electrocatalysis of CO₂ toward multicarbon (C₂₊) products have multifaceted applications in the energy and chemical industries, offers an attractive route to mitigate carbon emissions and abate the depletion of fossil fuels. However, the productivity of CO₂-to-C₂₊ products suffers from a low selectivity and reaction rate owing to the difficulty in C–C coupling and the multiple electron-proton transfer steps. Recently, numerous tandem catalysts have been developed to improve the selectivity and formation rate of CO₂-to-C₂₊ products via coupled multiple reaction steps, exhibiting high industrial practicability. This review summarized recent progresses in the formation of C₂₊ products from CO₂ electrolysis on tandem catalysts. In this review, we highlight the cooperative regulation strategy of tandem catalysts formed by introducing different types of new components and reveal the relationships between *CO intermediate mass transport and the selectivity of C₂₊ products. Moreover, theoretical insight into the tandem catalytic mechanisms underlying the enhanced C₂₊ selectivity is also provided. Finally, the remaining challenges and opportunities for the electrocatalytic CO₂ toward C₂₊ products are discussed.