Interactions between Graphene Nanosheets and Copper Oxide Promote C ₂ Formation in Rapid CO ₂ Electroreduction

Copper-based catalysts can electrochemically reduce carbon dioxide into valuable multicarbon products, offering a promising solution to mitigate atmospheric CO2 levels. However, their practical application is hindered by limited product selectivity and an insufficient C2 current density at high operating currents. To overcome these limitations, in this study, we develop graphene-supported copper oxide electrocatalysts aimed at enhancing the catalytic performance of the CO2 reduction reaction (CO2RR) to C2 products. This enhancement is attributed to strong electronic interactions between the copper d-orbitals and carbon species, together with improved electrical conductivity, as evidenced by soft X-ray absorption spectroscopy and electrochemical impedance spectroscopy. The resulting electrocatalyst achieves a Faradaic efficiency of 70.45% for C2 products at 400 mA/cm2, with a partial current density of 281.8 mA/cm2. This performance markedly surpasses that of the benchmark copper electrocatalyst, which exhibits a comparable Faradaic efficiency of 70.27% only at 200 mA/cm2, with a partial current density of 140.54 mA/cm2. Operando X-ray absorption spectroscopy reveals that CuO is rapidly reduced to a metallic state under reaction conditions, resembling the metallic copper benchmark; however, the interfacial interaction between copper and carbon enriches crucial reaction intermediates during the CO2RR, as evidenced by Operando Raman spectroscopy, in good agreement with the observed electrochemical product distribution. These findings provide valuable insights for the design of CO2RR electrocatalysts and contribute to the advancement of Net Zero emissions.