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

In this work, Graphene (GN)/ZnO/Cu₂O electrodes were fabricated and tested for CO₂ electroreduction in 0.5 M 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 ∼4 mA/cm² for GN/ZnO to ∼8 mA/cm² for GN/ZnO/Cu₂O at −1.8 V 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% (∼1.34 ppm) for GN/ZnO/Cu₂O (with a ZnO/Cu₂O weight ratio of 2:1) at an applied potential of −0.9 V vs. Ag/AgCl.