Constructing Favorable Microenvironment on Copper Grain Boundaries for CO Electro-conversion to Multicarbon Products.

The electrochemical CO reduction reaction (eCORR) to multicarbon chemicals provides a promising avenue for storing renewable energy. Herein, we synthesized small Cu nanoparticles featuring enriched tiny grain boundaries (RGBs-Cu) through spatial confinement and electroreduction. spectroscopy and theoretical calculations demonstrate that small-sized Cu grain boundaries significantly enhance the adsorption of the *CO intermediate, owing to the presence of abundant low-coordinated and disordered atoms. Furthermore, these grain boundaries, generated under high current conditions, exhibit excellent stability during the eCORR process, thereby creating a stable *CO-rich microenvironment. This high local *CO concentration around the catalyst surface can reduce the energy barrier for C-C coupling and significantly increase the Faradaic efficiency (FE) for multicarbon products across both neutral and alkaline electrolytes. Specifically, the developed RGBs-Cu electrocatalyst achieved a peak FE of 77.3% for multicarbon products and maintained more than 134 h stability at a constant current density of -500 mA cm.