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Investigation of Electrocatalytic Properties of Pt/Mo - Expanded Graphite Composite Derived from Graphite Intercalation Compound

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Urbaniak J., Skowroński J.
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issue 3
442-446
EN
In the present work, electrocatalytic properties of Pt-EG and Pt/Mo-EG composite electrodes are studied. These composites were prepared by a three-step synthesis. First, stage-1 HClO_4-GIC was synthesized using the chronopotentiometric method. Then, HClO_4-GIC was heat treated to obtain expanded graphite. Finally, expanded graphite was coated with platinum catalyst from a water-alcohol solution of H_2PtCl_6. MoCl_5-GIC synthesized in parallel was subjected to thermal exfoliation to get Mo-EG composite onto which platinum catalyst was dispersed. The X-ray diffraction and energy dispersive X-ray analyses coupled with scanning electron microscopy were applied for characterizing the obtained GICs and EG-based composites, whereas cyclic voltammetry was used to study electrocatalytic properties of Pt/EG and Pt/Mo-EG composite electrodes in sulfuric acid and sulfuric acid admixed with methanol.
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Free Volume of PVA/SSA Proton Exchange Membrane Studied by Positron Annihilation Lifetime Spectroscopy

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Gomaa M., Hugenschmidt C., Dickmann M., Abdel-Hamed M., Abdel-Hady E., Mohamed H.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1519-1522
EN
Humidity control and water management in polymer electrolyte membranes for fuel cells are still of high importance to improve the fuel cells' efficiencies. In this study, poly (vinyl alcohol) (PVA)was crosslinked using 15 wt% sulfosuccinic acid (SSA) by a solution casting method and additionally thermally crosslinked at 100°C. Positron annihilation lifetime spectroscopy was used to study the mean free volume size and the distribution at different humidity. A slight decrease in the free volume was found up to a relative humidity of 30% whereas it increases strongly for a relative humidity of more than 30%. The volume of the voids duplicates from 0.036 to 0.078 nm³ by changing the relative humidity from 30 to 80%. Thermogravimetric analyzer was used to determine the thermal stability of the membrane. From thermogravimetric analyzer data, it was found that the PVA with 15 wt% SSA membrane are chemically stable up to 200°C.
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