Cu Nanocrystals on Carbon Nitride for the CO2 Reduction Reaction

A facile one-step method was developed to promote the carbon dioxide reduction reaction (CRR) activities to form the C2 products (C2H4 and C2H5OH) via the capping agent and organic solvent-free involvement of copper (Cu) on graphitic carbon nitride (GCN). By tuning the using amount of the Cu precursor, Cu-GCN-0.2 exhibited a total Faradaic efficiency (FE) of more than 86.69 ± 0.73% for the C1 species (CO, CH4, HCOOH) and C2 species (C2H5OH, C2H4) as the CRR products when the electrolysis was carried out at an overpotential of 0.7 V (vs RHE) even after 12 h electrocatalysis and at a ratio of about 1:1 for C2/C1. Further investigation confirms that the enhanced CRR activities can be ascribed to three aspects: Firstl'y, smartl'y regulation of the Cu involvement during the synthesis of GCN created the CRR active site, which enables more CO2 to be adsorbed and activated at a lower overpotential to participate in the C–C couple procedures. Secondly, the neglected HER active site was formed when Cu was involved, which enables the well-maintained proton generation and adsorption activities for the proton-coupled electron transfer procedures, leading to the promoted C2/C1 ratio. Thirdly, the decreased electronic resistance accelerates the electronic transfer speed, which enables a faster reaction rate and a promoted long-term durability performance. This research provides a facile method for the rational construction and preparation of the electrocatalyst toward large-scale utilization in sustainable conversion and application.