Ethylene Glycol Electro-Oxidation on Platinum-Free Surfaces: How the Composition of PdRuRh Surfaces Influences the Catalysis

In this work we performed electrochemical (cyclic voltammetry and chronoamperommetry) and spectroelectrochemical studies (in situ Fourier transform infrared (FTIR)) in PdRuRh electrodeposits in acidic media in presence of ethylene glycol (0.5, 1.0 and 2.0 mol L-1). The electrochemical results show that the ethylene glycol oxidation is sensitive to the composition of the catalysts, being PdRuRh 74:09:17 the composition which presents the best catalytic activity. Also, conversely to Pt, these surfaces do not present a self-inhibitory effect when the EG concentration is increased. FTIR results indicate a complex reaction mechanism under these conditions, where glycolic acid, oxalic acid, formic acid and CO2 are detected as electro-oxidation products. The best catalytic activity observed for PdRuRh 74:09:17 can be understood in terms of a higher selectivity towards the production of CO2, which is the oxidation pathway that involves the release of the major number of electrons.