Comparative studies of ethylene glycol electrooxidation by Pt and Pd nanoparticles supported on different conducting polymers – A DEMS study

Abstract

Abstract The electrocatalysis of ethylene glycol oxidation (EGO) by platinum (Pt) or/and palladium (Pd) metal nanoparticles supported on three conducting polymers, poly-1,5-diaminonaphthalene (p-1,5-DAN), poly-1,8-diaminonaphthalene (p-1,8-DAN), and poly-1,2 diaminoanthraquinone (p-1,2-DAAQ) on a glassy carbon (GC) electrode was investigated at room temperature under a constant electrolyte flow using in situ differential electrochemical mass spectrometry (DEMS). The impact of the three different polymers as support materials on the catalytic activity of EGO was examined. During potentiodynamic measurements, both the faradaic current and the ionic signals corresponding to carbon dioxide (CO2) formation were continuously monitored. For the different catalysts, it was found that EG adsorption was prevented at very low potentials due to blocking by the underpotential deposition of hydrogen species and dissociative adsorption was enhanced upon an increase in the potential. During EGO, CO2 evolution was prohibited at the onset of OHad formation at the surface. A quantitative comparison of CO2 formation was evaluated for these modified conducting polymers. The trend in the current efficiency with respect to CO2 formation was found to be in the order of Pt/Pd/p-1,8-DAN/GC > Pt/Pd/p-1,5-DAN/GC > Pt/Pd/p-1,2-DAAQ/GC (shell–core). The current efficiency of CO2 production at the Pt/Pd/p-1,8-DAN/GC electrode was recorded as 87.5%, which is higher than reported in the literature. The roles played by the three studied polymers are discussed in this study, in which P-1,8-DAN shows excellent behavior as an attractive material for supporting metal nanoparticles due to its high active surface area and high electrical conductivity.