A fast and inexpensive strategy to fabricate ZnO-Cu composites as non-precious electrocatalysts for ethanol oxidation reaction in alkaline media

Here, we report the successful synthesis of ZnO-Cu nanocomposites through a two-step modified polyol route: First, the Cu precursor was microwave heated in ethylene glycol, water, and NaOH solution. Subsequently, ZnO was formed by adding a mixture containing ZnCl2. We evaluated the physical and chemical characteristics of the obtained nanostructures by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Raman spectroscopy. The activity for the ethanol electrooxidation reaction (EOR) was determined by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. Based on the XRD results, we concluded that the material forms a ZnO-Cu composite with a crystallite size of 11.9 nm and 19 nm for the ZnO and Cu species, respectively. Raman results suggest the presence of oxygen deficiencies in the ZnO-Cu nanocomposite, a relevant finding considering that this phenomenon improves the electrical conductivity in ZnO-based materials. CV and CA indicated that incorporating Cu into the ZnO structure increases the current density of the EOR in alkaline media. EIS demonstrated that the improved catalytic activity is due to the lower charge transfer resistance in the ZnO-Cu, mainly attributed to the synergic effect between the ZnO and the Cu species. The current research reveals the potential of the two-step microwave-assisted polyol synthesis process to synthesize nanocomposites in a short heating time. This simple, scalable, and effective approach helps develop ZnO- Cu nanostructures or other ZnO-based electrocatalysts for efficient ethanol electrooxidation. [Graphics] .