Boosting methane selectivity in CO2 electroreduction via rational modulation of Cu0-Cu+ sites in Cu/Cu2O composite

Abstract

In the context of increasing global carbon emissions, electroreduction of CO2 to value-added chemicals, such as methane, has emerged as a promising strategy to address energy and environmental challenges. Copper-based catalysts have attracted significant attention in the electrocatalysis community due to their moderate adsorption energies for key reaction intermediates, enabling the simultaneous production of multiple value-added chemicals in CO2 electroreduction. Nevertheless, the low selectivity towards methane, a key target product, remains a major challenge. Previous research has indicated that the synergistic effect between Cu0 and Cu+ interface sites plays a pivotal role in governing the CO2 reduction reaction (CO2RR) pathway. However, the precise mechanism through which Cu0 active sites modulate the reaction remains poorly understood. In this work, a series of tailored Cu/Cu2O catalysts were synthesized via electroreduction of Cu2O precursors with predefined particle sizes. A systematic investigation was conducted to elucidate the relationship between the concentration of Cu0 species and methane selectivity during CO2RR. By integrating comprehensive material characterization techniques and in-depth electrochemical analyses, this study reveals that Cu0 sites enhance methane selectivity in CO2RR through multiple mechanisms, including the optimization of intermediate adsorption energies, the improvement of electronic conductivity at the catalyst-electrolyte interface, and the suppression of competitive hydrogen evolution reactions. This study provides substantial experimental evidence for understanding the working mechanism of active sites in copper-based catalysts. Moreover, it presents novel strategies for the rational design of highly efficient CO2RR catalysts, offering new perspectives for the development of this field.