Synthesis of Pd-Cu Bimetallic Electrocatalyst for Ethylene Glycol and Glycerol Oxidations in Alkaline Media

PdCu/C (XC-72) electrocatalyst was synthesized by a chemical reduction method using ethylene glycol as reaction media, polyvinylpyrrolidone as surfactant and sodium borohydride as reducing agent. Vulcan carbon XC-72 was employed as support and added through the PdCu synthesis procedure; further, Pd commercial (Pd/C, 20% ETEK) was used for comparison purposes. Physicochemical characterization consisted in XRD, XRF, EDS and TEM analyses. TEM micrographs showed the presence of semi-spherical nanoparticles with a particle distribution around 6 nm. X-ray diffraction patterns showed the typical face-centered cubic structure of Pd materials for commercial Pd and revealed a low crystallinity for PdCu/C. The XRF analysis showed a mass metal composition of 81% Pd and 19% Cu. EDS analysis was made to single particles exhibiting an average elemental composition of 92% Pd and 8% Cu. The electrocatalytic activity of PdCu/C and Pd/C was evaluated by cyclic voltammetry experiments toward ethylene glycol and glycerol oxidations using three concentrations (0.1, 1 and 3 M) and 0.3 M KOH as electrolyte. These experiments exhibited the superior performance of PdCu compared with commercial Pd by means of current densities associated to the electro-oxidation reactions where values at least 3-fold higher than Pd/C were found.