Pt-Ir Binary Electrodes for Direct Oxidation of Methanol in Low-Temperature Fuel Cells (DMFCs)

In this study, Pt-Ir binary electrodes were prepared by DC magnetron sputtering and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical techniques, and CO stripping. The effect of Ir loading in electrocatalytic activity was also explored. It was found that Ir doping up to 80 % resulted in an increase of the electrochemically active surface (EAS) area and better electrocatalytic performance toward methanol electrooxidation reaction (MOR). The above conclusion was confirmed by CO stripping experiments as well as during oxidation of methanol where the electrodes were used as anodes in a one-compartment cell. The electrode with the lower Pt loading (i.e., 20 %) exhibited better electrocatalytic activity than the pure Pt anode. The observed higher performances of Ir loading electrodes were attributed to the enhanced EAS of the Pt-Ir binary electrodes and the electronic interactions between Pt and Ir atoms.