The Effect of Platinum Electrocatalyst on Membrane Degradation in Polymer Electrolyte Fuel Cells

Bodner, Merit; Cermenek, Bernd; Rami, Mija; Hacker, Viktor

doi:10.3390/membranes5040888

Cited by 19 publications

(16 citation statements)

References 19 publications

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“…Thus, the amount of fluoride detected in the effluent water from the AST with 60 s of cathode starvation is with a total of 0.0026 µmol h −1 cm −2 lower than for the AST with 10 s of starvation with 0.0037 µmol h −1 cm −2 , giving an average fluoride emission rate of 0.0031 µmol h −1 cm −2 . This is within the range of reported fluoride emission rates .…”

Section: Resultssupporting

confidence: 86%

“…The performance was determined from polarization curves, the membrane resistance by electrochemical impedance spectroscopy, the hydrogen diffusion current by linear sweep voltammetry and the cathode electrochemical surface area by cyclic voltammetry. All measurements were performed at the beginning (BoT) as well as at the end of testing (EoT) and conducted as has been reported previously , using a IM6 potentiostat with an additional PP240 load (both ZAHNER‐elektrik GmbH& Co. KG, Kronach, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The effluent water was collected for further analysis , . A fluoride ion selective electrode (ISE) (9609BNWP from Thermo Fisher Scientific, Waltham, MA USA) was used to detect fluoride ions.…”

Section: Methodsmentioning

confidence: 99%

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Air Starvation Induced Degradation in Polymer Electrolyte Fuel Cells

et al. 2017

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While hydrogen starvation in fuel cells is intensely investigated and strategies for avoidance have been developed, almost no data are available for other unexpected events, such as malfunction of the air supply. In this study we induce oxygen starvation in a manner closer to failure in real systems than commonly applied accelerated stress tests. By cycling the cathode gas flow, two accelerated stress tests were introduced; simulating short periods of air starvation with duration of either 10 or 60 seconds. Short cathode undersupply does not lead to fuel cell failure. Air starvation results in a voltage drop and hydrogen evolution. This is accompanied by the reduction of platinum oxides in the respective areas, which leads to an improvement of the active catalyst surface area. After extensive cycling, degradation becomes the dominant effect. X‐ray computed tomography is used to visualize the change of the catalyst particle size and distribution in dependence on the location in the fuel cell. Throughout the experiments, a total voltage decay rate of 1.427 mV h−1, a total fluoride emission rate of 0.0031 µmol h−1 cm−2 and severe current and temperature gradients during starvation were observed, leading to an inhomogeneous agglomeration of the platinum electrocatalyst.

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Section: Resultssupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

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Air Starvation Induced Degradation in Polymer Electrolyte Fuel Cells

et al. 2017

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“…For the measurements, a piece of each membrane (b-f and 2-6) in size of 2.5 × 1.0 cm (in dry state) was alkalized in a 1.0 M KOH solution for approximately 24 h. After alkalization, the membrane was rinsed with ultra-pure water (~18 MΩ cm) and then immersed in ultra-pure water for another 24 h. Finally, the full hydrated membrane sample was incorporated into the four electrode configuration of the conductivity clamp and placed into ultra-pure water. The conducted measuring procedure has been reported previously [35][36][37].…”

Section: Ion Exchange Capacity (Iec)mentioning

confidence: 99%

Chitosan-Based Anion Exchange Membranes for Direct Ethanol Fuel Cells

Feketeföldi

Cermenek²,

Spirk

et al. 2016

J Membra Sci Technol

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A series of novel cross-linked highly quaternized chitosan and quaternized poly (vinyl alcohol) membranes were successfully synthesized to be applied in alkaline direct ethanol fuel cells. Cross-linking was accomplished using two different cross-linking agents and an additional thermal process to improve both chemical and thermal properties. Equivalent blends of chitosan and poly (vinyl alcohol) membranes with various degrees of cross-linking were prepared by using different amounts of glutaraldehyde and ethylene glycol diglycidyl ether as cross-linkers. To investigate their applicability in direct ethanol fuel cells, the membranes were characterized in terms of their structural properties, chemical, thermal and alkaline stability, ion transport and ionic properties using following methods: Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis, water uptake by mass change, ethanol permeability in the diffusion cell, back titration method (ion exchange capacity) and electrochemical impedance spectroscopy (anion conductivity). Despite the high degree of quaternization of the applied materials and regardless of the thin film thickness of the blend membranes, the novel cross-linked products displayed outstanding mechanical stability. The lower crosslinked membranes exhibited the best transport and ionic properties with a high anion conductivity of 0.016 S cm-1 and a high ion exchange capacity of 1.75 meq g-1 , whereas membranes with a higher degree of cross-linking performed superior in terms of reduced ethanol permeability of 3.30•10-7 cm 2 s-1 at 60°C. The blend membranes-chemically and thermally cross-linked-provide excellent thermal stability with an onset degradation temperature above 280°C and superb alkaline stability in 1.0 M KOH at 60°C for 650 h. Therefore, these composite membranes exhibit high potential for application as alkaline electrolytes in fuel cells.

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“…30 Contrary to the consensus, there is a report that the platinum catalyst detoxies hydrogen peroxide and inhibits the decomposition of Naon. 31 It is also noted that Naon is easily destroyed by exposure to radiation such as g rays, b rays, [32][33][34][35][36] XAFS measurement, 37 XPS measurement 38 and EELS measurement. 39 X-ray absorption ne structure spectroscopy (XAFS: further divided into XANES and EXAFS depending on the energy region) enables us to carry out element-selective observations of chemical states and local structures.…”

Section: Introductionmentioning

confidence: 99%