Constructing Favorable Microenvironment on Copper Grain Boundaries for CO<sub>2</sub> Electro-conversion to Multicarbon Products.

Kong, Yan; Yang, Hengpan; Jia, Xinmei; Wan, Da; Zhang, Yilei; Hu, Qi; He, Chuanxin · Nano Lett · 2024

basic_science · Level V

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Abstract

The electrochemical CO<sub>2</sub> reduction reaction (eCO<sub>2</sub>RR) 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 <i>in situ</i> electroreduction. <i>In-situ</i> 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 <i>in situ</i> under high current conditions, exhibit excellent stability during the eCO<sub>2</sub>RR 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<sup>-2</sup>.