Palladium-ruthenium alloy nanoparticles dispersed on CoWO4-doped graphene for enhanced methanol electro-oxidation

Highly dispersed nanoparticles (NPs) of Pd and Pd-Ru alloys on the 10 wt% CoWO4-doped GNS (graphene nano sheets) support have been obtained by a microwave-assisted polyol reduction and investigated for their application as efficient electrode materials for methanol oxidation reaction (MOR). Structural and electrocatalytic surface characterization of hybrid materials were carried out by XRD, TEM, XPS, cyclic voltammetry and chronoamperometry. Pure CoWO4 and CoWO4-doped GNS follow the monoclinic crystal structure and the Pd NPs (6–7 nm) dispersed on CoWO4-doped GNS follow the face-centered cubic crystal structure. It is observed that with the increase of Pd loading from 5 to 20 mg on the support, the onset potential (Eop) for MOR shifts negatively and the MOR current density increases, the magnitude of shift in Eop and increase in the MOR peak current density being the greatest in the case of 15 mg Pd loading. Introduction of Ru from 0.6 to 2.0 mg into 15 mg Pd on the catalyst support, the apparent activity of the active catalyst, 15Pd/10 wt% CoWO4-GNS improved further, the magnitude of improvement, however, being the greatest (≈50%) with 1.0 mg Ru. Thus, novel 15Pd-1.0Ru/10 wt%CoWO4-doped GNS can be a promising electrode material for MOR in alkaline solutions.