Application of TGA techniques to analyze the compositional and structural degradation of PEMFC MEAs

Lee, Hye-Jin; Cho, Min Kyung; Jo, Yoo Yeon; Lee, Kug‐Seung; Kim, Hyung‐Juhn; Cho, EunAe; Kim, Soo-Kil; Henkensmeier, Dirk; Lim, Tae‐Hoon; Jang, Jong Hyun

doi:10.1016/j.polymdegradstab.2012.03.016

Cited by 38 publications

(16 citation statements)

References 39 publications

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“…As shown in Figure , the TG, DTG, and DSC plots of half-MEA, standard electrode, and standard catalyst show the typical thermal degradation behaviors characteristic of materials with multiple phases/components. The DSC (Figure b,d,f) and more clearly the DTG (Figures a,c,e) peaks at 310, 420, 540, 620, and 660 °C may be assigned to the weight losses corresponding to the ionomer in a catalyst layer, PEM/catalyst support carbon, Teflon of GDL, and microporous and mesoporous layers of GDL, respectively. − While no significant difference in the degradation temperatures of the GDL components (Teflon, microporous, and mesoporous layers) is observed, the degradation temperatures of the catalyst layer components (ionomer and carbon support) exhibit a significant increment for the post-AST samples, as one can see more clearly in Figure b (Std. cat.).…”

Section: Resultsmentioning

confidence: 93%

“…The DSC (Figures 5b, 5d, 5f) and more clearly the DTG peaks (Figures 5a, 5c, 5e) at 310, 420, 540, 620, 660 o C may be assigned to the weight losses corresponding respectively to ionomer in catalyst layer, PEM/catalyst support carbon, Teflon of GDL, microporous and mesoporous layer of GDL, respectively. [31][32][33][34] While no significant difference in the degradation temperatures of the GDL components (Teflon, microporous and mesoporous layers) is observed, the degradation temperatures of the catalyst layer components (ionomer and carbon support) exhibit significant increment for the post-AST samples, as can be observed more clearly in Fig. 5b (Std.…”

Section: Thermal Analysismentioning

confidence: 99%

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Quantification on Degradation Mechanisms of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers during an Accelerated Stress Test

Sharma

Andersen

2018

ACS Catal.

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The long-term durability of the catalyst layers of a lowworking temperature fuel cell such as a polymer electrolyte membrane fuel cell (PEMFC) is of significant scientific interest because of their operation criteria and high initial cost. Identification of degradation mechanisms quantitatively during an accelerated stress test (AST) is essential for assessing and improving the durability of such catalyst layers. In this study, we present a quantitative analysis of the degradation mechanisms such as (i) electronic connectivity loss due to carbon support corrosion, (ii) proton connectivity loss due to ionomer/catalyst interface loss, (iii) catalyst loss due to dissolution or detachment, and (iv) physical surface area loss due to particle growth that is responsible for the electrochemical surface area (ECSA) loss in Pt-based catalyst layers for PEMFCs during an AST performed through potential cycling (linear sweep cyclic voltammetry) between 0.4 and 1.6 V for 7000 cycles in Ar-saturated 1 M H 2 SO 4 . Using a half-membrane electrode assembly (half-MEA), where a gas diffusion electrode with genuine three-phase boundaries is used as a working electrode through a solid electrolyte, we have observed the ECSA loss due to ionomer/catalyst interface loss and identified a catalyst heterogeneous degradation pattern during an AST. Results suggest a significant ECSA loss due to catalyst isolation (∼64% of ECSA loss) from loss of electron and proton connectivities by catalyst support corrosion (∼45%) and ionomer/catalyst interface loss (∼19%), followed by particle growth (∼30%) and dissolution/detachment (6%). Such knowledge and methodology can effectively contribute to catalyst material screening and electrode structure development to advance the PEMFC technology.

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Section: Resultsmentioning

confidence: 93%

Section: Thermal Analysismentioning

confidence: 99%

Quantification on Degradation Mechanisms of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers during an Accelerated Stress Test

Sharma

Andersen

2018

ACS Catal.

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“…Currently, TGA has been commonly utilized as an effective tool for studying the thermolysis of chemicals 6 31 32 . Specifically, the thermal stability of PFSA membranes (e.g., Nafion) has been previously studied by this method 6 33 34 .…”

Section: Discussionmentioning

confidence: 99%

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Feng

Wei

et al. 2015

Sci Rep

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The thermal decomposition of Nafion N117 membrane, a typical perfluorosulfonic acid membrane that is widely used in various chemical technologies, was investigated in this study. Structural identification of thermolysis products in water and methanol was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). The fluoride release was studied using an ion-chromatography system, and the membrane thermal stability was characterized by thermogravimetric analysis. Notably, several types of perfluorinated compounds (PFCs) including perfluorocarboxylic acids were detected and identified. Based on these data, a thermolysis mechanism was proposed involving cleavage of both the polymer backbone and its side chains by attack of radical species. This is the first systematic report on the thermolysis products of Nafion by simulating its high-temperature operation and disposal process via incineration. The results of this study indicate that Nafion is a potential environmental source of PFCs, which have attracted growing interest and concern in recent years. Additionally, this study provides an analytical justification of the LC/ESI-MS/MS method for characterizing the degradation products of polymer electrolyte membranes. These identifications can substantially facilitate an understanding of their decomposition mechanisms and offer insight into the proper utilization and effective management on these membranes.

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“…TGA analysis is widely used in both academic research and industry for routine characterization because the sampling and analysis is straightforward and less expensive than other techniques. 1 In our view, uniformity of distribution of platinum nanoparticles on the surface and in the pores of carbon microparticles as well as the presence of agglomerates (consisting of a large number of nanoparticles) loosely connected with the support may have a significant effect on the kinetics of thermal carbon oxidation. An additional interest in the study of kinetics of high-temperature oxidation of platinum−carbon electrocatalysts is the fact that the degradation of cathodic catalyst in a low-temperature fuel cell is ascribed to carbon support oxidation by intermediates formed during electroreduction of oxygen on the surface of nanoparticles (radicals OOH*, H 2 O 2 , etc.).…”

Section: Introductionmentioning

confidence: 90%

Reasons for the Differences in the Kinetics of Thermal Oxidation of the Support in Pt/C Electrocatalysts

et al. 2014

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High-temperature oxidation processes of carbon microparticles Vulcan XC72 coated with platinum nanoparticles (Pt/C) were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The presence of different specific temperature ranges in the oxidation of carbon support was shown to be due to both the peculiarities of granulometric composition of carbon black microparticles, different size, and uneven spatial distribution of platinum nanoparticles in the pores and on the surface of the carbon support. The correlation between the length of a section in the thermograms and the fraction of carbon microparticles poorly coated with platinum can be used to analyze the uniformity of Pt nanoparticle spatial distribution in the metal–carbon catalysts and therefore to select electrocatalysts with optimal microstructure. This analysis is expected to be effectively utilized in order to assess the uniformity of platinum distribution on carbon microparticles and also to provide additional information about granulometric composition of carbon supports.

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Application of TGA techniques to analyze the compositional and structural degradation of PEMFC MEAs

Cited by 38 publications

References 39 publications

Quantification on Degradation Mechanisms of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers during an Accelerated Stress Test

Quantification on Degradation Mechanisms of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers during an Accelerated Stress Test

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Reasons for the Differences in the Kinetics of Thermal Oxidation of the Support in Pt/C Electrocatalysts

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