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

- Synthesis and characterization of graphene/ZnO/Cu2O structure at low temperature ∼34 °C.
- Under CO2 saturation, incorporation of Cu2O into graphene/ZnO result in a higher cathodic current density, and the largest current density value was obtained for catalyst with a ZnO/Cu2O weight ratio of 1:2.
- The maximum Faradaic efficiency for CO2 conversion to n-propanol was 30% using GN/ZnO/Cu2O (with a ZnO/Cu2O weight ratio of 2:1) at −0.9 V vs Ag/AgCl.

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.

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