Cu−based bimetallic sites' p-d orbital hybridization promotes CO asymmetric coupling conversion to C2 products

Abstract

Hampered by sluggish C−C coupling kinetics, the low selectivity and efficiency have limited industrial applications of CO₂ reduction into valuable multi-carbon products. A direct coupling of CO molecules or their coupling after hydrogenation, followed by the final synthesis of C₂ products, can help to overcome these limitations potentially. In this study, a detailed high-throughput screening of bimetallic site catalysts comprising copper (Cu) and 28 other metal (M) atoms was conducted. The metal atoms Cu and M were anchored on a carbon nanotube (CNT) with six nitrogen (N₆) defects (CuMN₆@CNT), which possesses effective dual active sites for C−C coupling. The calculated results demonstrate that the CuGaN₆@CNT catalyst exhibited favorable selectivity, with low theoretical overpotentials of −0.23 and −0.34 eV for ethanol and ethylene, respectively, surpassing most reported catalysts. The synergistic effect of Ga and Cu sites, along with their p-d states hybridization, results in an enhancement of Cu's d state dispersion and energy barriers reduction for C−C coupling. Additionally, the strain effect of the substrate CNT exhibits a direct correlation with the catalytic performance of CuGaN₆@CNT by adjusting the d-band center of the Cu site and p-band center of the Ga site. These findings provide a novel insights into the electrocatalytic reduction of CO into valuable C₂ products using bimetallic single atom catalyst, offering significant guidance for future research endeavors in this field.