Dual‐Confinement Structure Design Enables Synergistic Modulation of Local Microenvironment and Electronic Structure for Enhanced CO 2 Electroreduction to CO

ABSTRACT Precisely tailoring the local microenvironment and interfacial electronic structure of electrocatalysts is crucial for achieving highly efficient and selective electrochemical CO 2 reduction reaction (CO 2 RR). Herein, we propose a dual‐confinement strategy and successfully construct a composite nanoreactor consisting of carbon nanotube (CNT) shells housing nickel nanoparticles encapsulated in nitrogen‐doped carbon. In this orchestrated architecture, the CNT serves as a primary confinement framework that effectively enriches OH − ions, creating an alkaline local microenvironment conducive to suppressing the hydrogen evolution reaction and stabilizing intermediates. The internal core–shell units of nitrogen‐doped carbon and nickel nanoparticles function as a secondary confinement system, where metal‐carbon interactions and controlled N‐doping species synergistically optimize the interfacial charge distribution. This configuration enhances the π‐p orbital coupling between active sites and CO 2 molecules, thereby facilitating CO 2 activation and conversion. Benefiting from the dual‐confinement effect with the synergistic regulation of the local microenvironment and electronic structure, the catalyst exhibits outstanding catalytic activity and achieves a remarkable CO Faradaic efficiency of 99% at −1.0 V vs. reversible hydrogen electrode. This work demonstrates that the design of multi‐level confined structures offers the potential for constructing highly efficient catalysts.