Investigation of ruthenium promoted palladium catalysts for methanol electrooxidation in alkaline media

In this study, the investigation of binary palladium based electrocatalysts for methanol oxidation in alkaline media is reported. For this purpose, electrocatalysts with a loading of 20wt% metal on VulcanXC72-R were synthesized via wet chemical reduction with various compositions of palladium and ruthenium. Physical characterization via transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and inductively coupled plasma optical emission spectroscopy (ICP-OES) was done and verified the synthesis of nanoparticles on carbon support. Electrochemical evaluation of the catalytic behavior of Pd/C, Ru/C and PdXRu/C (X = 1, 3, 5) via cyclic voltammetry and chronoamperometry was conducted in a 3-electrode setup. These measurements suggested that Pd3Ru/C is a promising material for methanol oxidation reaction in alkaline media with an onset potential of 0.465 V-RHE and a peak current density of over 1 A mg(-1)pd. To further investigate the oxidation of methanol on Pd/C and Ru promoted catalysts, differential electrochemical mass spectrometry (DEMS) measurements were done. From these results a higher CO2 current efficiency (CCE) of 86% for Pd3Ru/C compared to 65% for Pd/C was found. Moreover, fuel cell tests verified the results and showed that Pd3Ru/C has the better performance. (C) 2015 Elsevier B.V. All rights reserved.