ZnO nanorods as cost-effective electrocatalysts for ethanol electro-oxidation in an alkaline medium

Abstract

Ethanol oxidation reactions (EOR) using cost-effective electrocatalysts are crucial in fuel cell development. This study aims to investigate using ZnO nanorods/ITO as electrocatalysts in an alkaline medium. ZnO nanorods were electrodeposited on an ITO glass substrate from an aqueous solution containing different concentrations of ZnCl₂ at -1 V vs. SCE and 70 °C. X-ray diffraction shows that the thin films exhibit a good crystalline quality with a Wurtzite hexagonal structure and have a (002) preferential orientation along the c-axis. Furthermore, the SEM images show a formation of hexagonal nanorods with uniform distribution on the ITO surface. Moreover, the effect of zinc chloride concentration on the diameter was measured and varied from 150 to 322 nm. In addition, electrochemical impedance spectroscopy (EIS) was employed to study the charge transfer of the ZnO nanorods/electrolyte interface. The Mott-Schottky analysis has shown that the present materials are n-type semiconductors with a donor carrier density varied from 10.5 × 10²⁰ to 2.33 × 10²⁰ cm^− 3. The optical band gap value decreased from 3.45 eV to 3.00 eV as the zinc concentration increased. The EOR on ZN electrodes was carried out in 0.5 M NaOH solution at room temperature using cyclic voltammetry and chronoamperometry techniques. Furthermore, the current study proved that electrodeposited ZnO nanorods could be a promising electrocatalyst electrode for ethanol oxidation and its applications.

Graphical Abstract