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1

Microstructure Characterization of Nafion®g HP JP as a Proton Exchange Membrane for Fuel Cell: Positron Annihilation Study

100%

Mohamed H., Abdel-Hady E., Abdel-Hamed M., Said M.

Acta Physica Polonica A

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2017

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vol. 132

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issue 5

1543-1547

EN

Free volume size V_{f} and proton conductivity σ of a novel polymer electrolyte membrane were investigated as a function of temperature and relative humidity up to 140°C and 80%, respectively. The free volume size V_{f} for Nafion® HP JP reflect the α-transition temperature at about 98°C. In addition the free volume size V_{f} for Nafion® HP JP is smaller than that for Nafion® NRE212 membrane which leads to lower methanol permeability of the former membrane. The proton conductivity σ for Nafion® HP JP decreases with increase of temperature up to transition temperature due to free and bound water loss, then it starts to increase due to dynamic segmental motion. It increases for Nafion® HP JP with the increase of the relative humidity. A good correlation between V_{f} and σ was successfully established for both membranes which indicates that σ is governed by the free volume. In conclusion, Nafion® HP JP is a suitable membrane for a proton exchange membrane fuel cell application.

2

Proton Conductivity and Free Volume Properties in Per-Fluorinated Sulfonic acid/PTFE Copolymer for Fuel Cell

100%

Mohamed H., Abdel-Hady E., Abdel-Hamed M.

Acta Physica Polonica A

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2017

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vol. 132

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issue 5

1509-1514

EN

The proton conductivity mechanism in per-fluorinated sulfonic acid/PTFE copolymer Fumapem® membranes for polymer electrolyte membranes has been investigated. Three samples of Fumapem® F-950, F-1050 and F-14100 membranes with different ion exchange capacity 1.05, 0.95, and 0.71 meq/g, respectively, were used in this study after drying. The o-Ps hole volume size (V_{FV,Ps}) was quantified using the positron annihilation lifetime technique while the proton conductivities (σ ) were measured using LCR Bridge as function of temperature. It was found that as the ion exchange capacity increases, the proton conductivity increases and the free volume expands. Temperature dependences of proton conductivity and the o-Ps hole volume size (V_{FV,Ps}) reflect the glass transition temperature of the membrane. A good linear correlation between the reciprocal of the o-Ps hole volume size (1/V_{FV,Ps}) and log(σ)+Δ E_a/2.303k_{B}T, (where ΔE_a is the activation energy, T is the absolute temperature and k_{B} is the Boltzmann constant) at different temperatures indicate that the ionic motion in dry Fumapem® is governed by the free volume. A linear relationship between the critical hole size γ V*_{i} and the ion exchange capacity was also achieved.

3

Ion Beam Formation of Electrocatalysts for Direct Methanol and Ethanol Fuel Cells on the Basis of Carbon Catalyst Supports

88%

Poplavsky V., Dorozhko A., Luhin V., Matys V., Zukowski P., Czarnacka K.

Acta Physica Polonica A

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2017

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vol. 132

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issue 2

278-282

EN

Ion-beam modification of materials whose service properties are mainly controlled by the surface composition is of especial interest, in particular, for electrocatalysts, namely electrodes of fuel cells - perspective chemical current sources. A catalyst is needed for effective operation of fuel cell. In this paper active layers of the electrocatalysts were prepared by ion beam assisted deposition of catalytic (platinum) and activating (cerium) metals onto carbon (AVCarb® Carbon Fiber Paper P50 and Toray Carbon Fiber Paper TGP-H-060 T) catalyst supports. Formation of layers by ion beam assisted deposition by means of the deposition of metal and mixing of precipitating layer with the substrate by accelerated ions of the same metal, was carried out. Metal deposition and mixing between the precipitable layer and surface of the substrate by accelerated (U=10 kV) ions of the same metal were conducted from a neutral vapor fraction and plasma of vacuum arc discharge of a pulsed electric arc ion source. Study of the morphology and composition of layers was carried out by the scanning electron microscopy, energy dispersive X-ray microanalysis, X-ray fluorescence analysis, and the Rutherford backscattering spectrometry methods. According to the investigations with the use of cyclic voltammetry, the electrocatalysts with the prepared layers exhibited catalytic activity in the reactions of electrochemical oxidation of methanol and ethanol, which form the basis for the principle of operation of low temperature direct methanol and direct ethanol fuel cells.

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3 Acta Physica Polonica A

3 2017

2 Abdel-Hady E.

2 Abdel-Hamed M.

2 Mohamed H.

1 Czarnacka K.

1 Dorozhko A.

1 Luhin V.

1 Matys V.

1 Poplavsky V.

1 Said M.

1 Zukowski P.

Microstructure Characterization of Nafion®g HP JP as a Proton Exchange Membrane for Fuel Cell: Positron Annihilation Study

Proton Conductivity and Free Volume Properties in Per-Fluorinated Sulfonic acid/PTFE Copolymer for Fuel Cell

Ion Beam Formation of Electrocatalysts for Direct Methanol and Ethanol Fuel Cells on the Basis of Carbon Catalyst Supports