The effect of Cu-Mg-Fe layered double hydroxide on the electrocatalytic activity of gold nanoparticles towards ethanol electrooxidation

In this work, a Cu-Mg-Fe layered double hydroxide-gold nanoparticles composite on a glassy carbon electrode (LDH/AuNPs/GCE) was used as a novel electrocatalyst for ethanol oxidation in alkaline media. The LDH/AuNPs/GCE was fabricated by electrodeposition of AuNPs on a GCE, and followed by the deposition of the Cu-Mg-Fe LDH synthesized using a hydrothermal method. The surface morphology of the prepared electrode was characterized using field emission scanning electron microscopy (FE-SEM) and energy dispersive Xray spectroscopy (EDX), demonstrating the successful formation of the proposed catalyst. FE-SEM images showed that the electrodeposited AuNPs in the size of 50-100 nm are covered uniformly by the Cu-Mg-Fe LDH film consisting of fine nanoparticles and macropores. This morphology of the LDH increased the real surface area of the catalyst. In the next step, the catalytic performance of the LDH/AuNPs/GCE towards ethanol was compared with the AuNPs/GCE and AuNPs/LDH/GCE. The results showed the catalytic performance of the LDH/AuNPs/GCE is higher than the other electrodes. It was found that the adsorption of ethanol molecules on the Cu-Mg-Fe LDH, that increases their concentration around the active sites of AuNPs, plays a significant role in the enhancement of the catalytic activity of the LDH/AuNPs/GCE. Moreover, cyclic voltammetry and chronoamperomety tests indicated that Cu-Mg-Fe LDH results in an increase in the long-term stability of the LDH/AuNPs catalyst against the poisoning species, as compared with the AuNPs catalyst. Therefore, the Cu-Mg-Fe LDH/AuNPs composite is proposed as an efficient anodic electrode for use in direct ethanol fuel cells in alkaline media. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.