Graphene-supported Pd-Ru nanoparticles with superior methanol electrooxidation activity

摘要

Pd-Ru bimetallic nanoparticles dispersed on graphene nanosheets (GNS) have been obtained by a microwave-assisted polyol reduction method and investigated for methanol electrooxidation in 1M KOH + 1M CH3OH at 25 °C. Structural and electrochemical characterizations of electrocatalysts are carried out by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, CO stripping voltam-metry and chronoamperometry. The study shows that introduction of Ru (1-10 wt.%) into 40 wt.%Pd/GNS produces an alloy of Pd and Ru with the face centered cubic crystal structure. The electrocatalytic activity increased with increasing percentage of Ru in the Pd-Ru alloy showing maximum with 5 wt.%Ru. The electrocatalytic activity of the 40 wt.%Pd-5 wt.%Ru/GNS electrode at E = -0.10 V vs. Hg/HgO was ~2.6 times greater than that of the base (40 wt.%Pd/GNS) electrode. Based on the methanol oxidation current, measured at 1 h during the chronoamperometry tests at E = -0.10 V vs. Hg/HgO, the active 40 wt.%Pd-5 wt.%Ru/GNS electrode exhibited ~72% and ~675% higher poisoning tolerance as compared to 40%Pd/GNS and 40%Pd/multiwalled carbon nanotube electrodes, respectively.