Complementary Operando Spectroscopy identification of in-situ generated metastable charge-asymmetry Cu2-CuN3 clusters for CO2 reduction to ethanol

Copper-based materials can reliably convert carbon dioxide into multi-carbon products but they suffer from poor activity and product selectivity. The atomic structure-activity relationship of electrocatalysts for the selectivity is controversial due to the lacking of systemic multiple dimensions for operando condition study. Herein, we synthesized high-performance CO2RR catalyst comprising of CuO clusters supported on N-doped carbon nanosheets, which exhibited high C2+ products Faradaic efficiency of 73% including decent ethanol selectivity of 51% with a partial current density of 14.4 mA/cm(-2) at -1.1 V vs. RHE. We evidenced catalyst restructuring and tracked the variation of the active states under reaction conditions, presenting the atomic structure-activity relationship of this catalyst. Operando XAS, XANES simulations and Quasi-in-situ XPS analyses identified a reversible potential-dependent transformation from dispersed CuO clusters to Cu-2-CuN3 clusters which are the optimal sites. This cluster can't exist without the applied potential. The N-doping dispersed the reduced Cu-n clusters uniformly and maintained excellent stability and high activity with adjusting the charge distribution between the Cu atoms and N-doped carbon interface. By combining Operando FTIR and DFT calculations, it was recognized that the Cu-2-CuN3 clusters displayed charge-asymmetric sites which were intensified by CH3* adsorbing, beneficial to the formation of the high-efficiency asymmetric ethanol. Copper-based materials can convert carbon dioxide into multi-carbon products but suffer from poor activity and selectivity. Here, the authors report CuO clusters supported on nitrogen-doped carbon nanosheets for the reduction CO2-to-ethanol, and investigate the change in the catalytic sites while in operation.

Automated summary

This article investigates the activity and selectivity issues of copper-based materials in converting carbon dioxide into multi-carbon products, and reports a high-performance CO2RR catalyst. Through in-situ experiments and computational methods, the authors demonstrate the atomic structure-activity relationship of the catalyst and reveal the potential-dependent transformation of Cu-2-CuN3 clusters and the role of charge-asymmetric sites in efficient ethanol formation.