Local CO Generator Enabled by a CO-Producing Core for Kinetically Enhancing Electrochemical CO 2 Reduction to Multicarbon Products.

CO plays a crucial role as an intermediate in electrochemical CO 2 conversion to generate multicarbon (C 2+ ) products. However, optimizing the coverage of the CO intermediate (*CO) to improve the selectivity of C 2+ products remains a great challenge. Here, we designed a hierarchically structured double hollow spherical nanoreactor featuring atomically dispersed nickel (Ni) atoms as the core and copper (Cu) nanoparticles as the shell, which can greatly improve the catalytic activity and selectivity for C 2+ compounds. Within this configuration, CO generated at the active Ni sites on the inner layer accumulates in the cavity before spilling over neighboring Cu sites on the outer layer, thus enhancing CO dimerization within the cavity. Notably, this setup achieves a sustained faradaic efficiency of 74.4% for C 2+ production, with partial current densities reaching 337.4 mA cm -2 . In situ Raman spectroscopy and finite-element method (FEM) simulations demonstrate that the designed local CO generator can effectively increase the local CO concentration and restrict CO evolution, ultimately boosting C-C coupling. The hierarchically ordered architectural design represents a promising solution for achieving highly selective C 2+ compound production in the electroreduction of CO 2 .