Novel fabrication of PdCu nanostructures decorated on graphene as excellent electrocatalyst toward ethanol oxidation

In this study, the electrochemical reduction reaction of copper(II) formate on the graphene/glassy carbon electrode (G/GCE) surface in the HCl (5 wt.%) was employed for fabrication of the Pd-Cu nanostructures by galvanic displacement reaction. This method has a number of advantages including being environmentally-friendly, simplicity, inexpensiveness and fast. The Pd-Cu nanostructures decorated on the G/GCE were fabricated in two steps: (1) electrochemical reduction reaction of copper(II) formate to Cu on the G/GCE and (2) the galvanic replacement reaction between Cu and Pd2+ ions. The physical and electrochemical properties of as-prepared Pd-Cu/G were investigated via Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Cyclic Voltammetry, Chronoamperometry, and Electrochemical Impedance Spectroscopy. The Pd-Cu/G compositional effect on ethanol oxidation in alkaline media is investigated. The results were shown that the catalytic activity and durability of Pd-Cu/G catalyst are superior to those of Pd/C electrocatalyst for ethanol oxidation. The Pd-Cu/G increased the current density 6.2 times more than Pd/C with a 50 my negative shift in onset potential for electrooxidation of ethanol. Besides, the novel Pd-Cu/G catalyst exhibits large electrochemically active surface area, lower apparent activation energy, higher levels of stability, poisoning tolerance, and lower charge transfer resistance compared to the Pd/C for the oxidation of ethanol. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier. Ltd. All rights reserved.