Hollow Cu 2 O@CoMn 2 O 4 Nanoreactors for Electrochemical NO Reduction to NH 3 : Elucidating the Void‐Confinement Effects on Intermediates

Abstract Hollow nanoreactors show great potential in catalysis due to the void‐confinement effect. Yet few studies have investigated the void‐confinement effect of hollow nanoreactors on intermediates. Herein, electrochemical NO reduction to NH 3 (ENOR) is used as a probe reaction to study the void‐confinement effect of hollow Cu 2 O@CoMn 2 O 4 nanoreactors on intermediates. Combined with the results of catalytic activity, H 2 ‐treated in situ diffusion Fourier transform infrared spectroscopy and the finite‐element method simulation confirm that the void‐confinement effect on the intermediate is the main reason for enhanced ENOR efficiency. Additionally, theoretical calculations also show that the Cu sites of Cu 2 O@CoMn 2 O 4 nanoreactors are favorable for the formation of *NOH intermediates. This work not only gives an insight into void‐confinement effect of hollow nanoreactors on intermediates but also provides a valuable strategy for improving ENOR.