Grain-Boundary-Enriched Copper Electrocatalysts for Efficient Carbon Dioxide Reduction to Multi-Carbon Products

The electrocatalytic carbon dioxide reduction reaction (CO2RR) provides a promising strategy for converting CO2 into valuable chemicals, with multicarbon (C2+) products being particularly attractive due to their diverse industrial applications. Grain boundaries in Cu-based electrocatalysts have been demonstrated to improve the selectivity of the CO2RR toward C2+ products. However, methods for creating grain boundaries in Cu remain limited. Herein, a grain-boundary-enriched Cu electrocatalyst (GB-Cu) was successfully synthesized via in situ electrodeposition, in which sodium pyridine-2-carboxylate is introduced as an additive to control the deposition kinetics and generate new active species through the presence of GB. In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy reveals that the abundance of grain boundaries enhances CO adsorption during C–C coupling. This leads to a significantly higher Faradaic efficiency (FE) of 57.7% for C2+ products, with a notable 43% for C2H4, in the H-cell. Furthermore, GB-Cu demonstrated high C2+ selectivity over a wide range of current densities (100–250 mA cm–2) in a flow cell, achieving the highest C2+ FE of 50.03% at 100 mA cm–2.