A comparative study of electrochemical methods on Pt-Ru DMFC anode catalysts: The effect of Ru addition

In the present study comparative electrochemical study of methanol electro-oxidation reaction, the effect of ruthenium addition and experimental parameters on methanol electro-oxidation reaction at high performance carbon supported Pt and Pt-Ru catalysts have been studied by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in H2SO4 (0.05-2.00 M) + CH3OH (0.01-4.00 M) at 20-70 degrees C. Tafel plots for the methanol oxidation reaction on Pt and Pt-Ru catalysts show reasonably well-defined linear region with the slopes of 128-174 mV dec(-1)(alpha = 0.34-0.46). The activation energies from Arrhenius plots have been found as 39.06-50.65 kJ mol(-1). As a result, methanol oxidation is enhanced by the addition of ruthenium. Furthermore, Pt-Ru (25:1) catalyst shows best electro-catalytic activity, higher resistance to CO, and better long term stability compared to Pt-Ru (3:1), Pt-Ru (1:1), and Pt. Finally, the EIS measurements on Pt-Ru (25:1) catalyst reveals that methanol electro-oxidation reaction consists of two process: methanol dehydrogenation step at low potentials (<700 mV) and the oxidation removal of COads by OHads at higher potentials (>700 mV). Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.