Oxide-derived Cu-Zn nanoparticles supported on N-doped graphene for electrochemical reduction of CO2 to ethanol

Abstract

The oxide-derived Cu and Zn nanoparticles (prepared by co-precipitation method) supported on N-doped graphene (CuZnx/NGN) were prepared and ZnO loading was optimized for efficient electrochemical CO2 reduction (ECR) to multi-carbon products. The ECR experiments were performed in aqueous 0.1 M KHCO3 electrolyte at ambient pressure. Results suggest that the Faradaic efficiency (FE) for multicarbon products could be tuned by varying the loading of Zn in the CuZnx/NGN. The catalyst with 20 wt% ZnO loading (CuZn20/NGN) gives the highest FE of 34.25% for ethanol production and 12.38% for N-propanol at −0.8 V (vs. RHE) with the total current density of 3.95 mA cm−2. The CuZn20/NGN electrode shows long term stability of at least 24 h at optimized conditions. It is suggested that CO generated at the reduced ZnO nanoparticles increases the local surface coverage of *CO on the reduced CuO, which improves the C-C coupling rate, facilitating the multi-carbon production (i.e. ethanol).