Steering C–C Coupling by Hollow Cu₂O@C/N Nanoreactors for Highly Efficient Electroreduction of CO₂ to C₂₊ Products

Electrochemical CO 2 reduction reaction offers a promising pathway to transform renewable electricity into value‐added fuels and feedstocks in the form of chemical energy. However, the *CO intermediates tend to obtain protons or electrons to generate C 1 products. The Cu + , an active catalytic site for C 2+ products, is easily reduced to Cu 0 at cathodic potentials. Herein, a hollow cuprous oxide protected by a thin N‐doped carbon shell (H–Cu 2 O@C/N) as an efficient nanoreactor to stabilize the Cu + species and enhance the coverage concentration of *CO on the local catalyst surface under the spatial confinement effect is designed, which efficiently accelerates C–C coupling to generate C 2+ products. As a result, H–Cu 2 O@C/N exhibits an outstanding C 2+ Faradaic efficiency of 75.9% with a partial current density of 248.8 mA cm −2 in the membrane electrode assembly (MEA) electrolyzer. Density functional theory combined with operando characterizations confirm that the N‐doped carbon layer protects the Cu + active species from electrochemical reduction, and the high coverage density of *CO from spatial confinement effect lowers the reaction barrier of *CH 2 CHO, thereby promoting C–C coupling. This work offers invaluable insights into the spatial confinement effect for boosting the steering C–C coupling in Cu‐based catalysts for efficient electroreduction of CO 2 to C 2+ products.