Graphene/ZnO/Cu2O electrocatalyst for selective conversion of CO2 into n-propanol

Abstract

In this work, Graphene (GN)/ZnO/Cu2O electrodes were fabricated and tested for CO2 electroreduction in 0.5M NaHCO3 electrolyte. The XRD, FESEM, and XPS results confirm the successful synthesis of the Cu(I) oxide and ZnO composites at low temperature 34°C, using simple wet-chemical approach. Linear sweep voltammetry and potentiostatic experiments were carried out for the GN/ZnO/Cu2O catalyst coated on Cu foil. In CO2 saturated electrolyte, the cathodic current density of the catalyst shows significant increase from ∼4mA/cm2 for GN/ZnO to ∼8mA/cm2 for GN/ZnO/Cu2O at −1.8V vs. Ag/AgCl, and the largest current density value was obtained for catalyst with a ZnO/Cu2O weight ratio of 1:2. The CO2 electroreduction on the GN/ZnO/Cu2O catalyst mainly produced n-propanol in the liquid product fraction. The maximum Faradaic efficiency for CO2 conversion to n-propanol was 30% (∼1.34ppm) for GN/ZnO/Cu2O (with a ZnO/Cu2O weight ratio of 2:1) at an applied potential of −0.9V vs. Ag/AgCl.