Electrocatalytic oxidation of ethanol on a glassy carbon electrode modified with a gold nanoparticle-coated hydrolyzed CaFe–Cl layered double hydroxide in alkaline medium

Abstract

The Ca–Fe–Cl LDH was synthesized by a co-precipitation method in alkaline medium. Then, Ca–Fe-LDH was shaken in deionized water to form the hydrolyzed structure (H–CaFe–Cl LDH). After that, the hydrolyzed form was immobilized on the AuNPs electrodeposited on the GCE (LDH/AuNPs/GCE) and the electrocatalytic activity of this modified electrode was investigated for the ethanol oxidation in alkaline medium. The characterizations and electrocatalytic activity of the H–CaFe-LDH structure and the prepared electrodes were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that the LDH/AuNPs/GCE exhibits a higher current density and lower onset potential for ethanol oxidation in comparison with the LDH/GCE, AuNPs/GCE and AuNPs/LDH/GCE. The high active surface area and the strong adsorption of ethanol into LDH flakes were known as the main factors enhancing the catalytic activity of the LDH/AuNPs/GCE. Moreover, the chronoamperometric and cyclic voltammetric results showed that the LDH flakes immobilized on the AuNPs/GCE play a critical role in the increase of the catalyst endurance against poisonous species. As a result, the proposed electrode can be used as a suitable anode in direct alcohol fuel cells.