Effect of morphology and structure of CuTCPP nanomaterials on the electrocatalytic CO2 reduction to methane and ethylene

The effect of Cu-N-4, Cu-O-4 and/or -COOH sites on the electrocatalytic CO2 reduction (ECR) activity and selectivity is rarely evaluated together and directly confirmed through the morphology and structure dependence of ECR performance. Here, the ECR performance of CuTCPP nanoparticles, nanorods, nanosheets and nanoflowers are systematically investigated. The experimental results show that their total ECR activity is nanoflowers > nanosheets > nanoparticles > nanorods. CuTCPP nanosheets with more Cu-N4 sites exposed showed the best ethylene selectivity of 40.6 % at -1.2 V vs. RHE. CuTCPP nanoflowers with more Cu-O-4 sites were more stable than the nanosheets, showing 61.0 % methane selectivity at -1.3 V vs. RHE. A series of characterizations reveal that Cu-O-4 is mainly responsible for methane production, while Cu-N-4 is the main active site for ethylene production and its synergy with Cu-O-4 or -COOH groups can improve the ethylene selectivity.