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Thapa BS, Pandit S, Mishra RK, Joshi S, Idris AM, Tusher TR. Emergence of per- and poly-fluoroalkyl substances (PFAS) and advances in the remediation strategies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170142. [PMID: 38242458 DOI: 10.1016/j.scitotenv.2024.170142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/20/2023] [Accepted: 01/11/2024] [Indexed: 01/21/2024]
Abstract
A group of fluorinated organic molecules known as per- and poly-fluoroalkyl substances (PFAS) have been commonly produced and circulated in the environment. PFAS, owing to multiple strong CF bonds, exhibit exceptional stability and possess a high level of resistance against biological or chemical degradation. Recently, PFAS have been identified to cause numerous hazardous effects on the biotic ecosystem. As a result, extensive efforts have been made in recent years to develop effective methods to remove PFAS. Adsorption, filtration, heat treatment, chemical oxidation/reduction, and soil washing are a few of the physicochemical techniques that have shown their ability to remove PFAS from contaminated matrixes. However these methods also carry significant drawbacks, including the fact that they are expensive, energy-intensive, unsuitable for in-situ treatment, and requirement to be carried under dormant conditions. The metabolic products released upon PFAS degradation are largely unknown, despite the fact that thermal disintegration methods are widely used. In contrast to physical and chemical methods, biological degradation of PFAS has been regarded as efficient method. However, PFAS are difficult to instantly and completely metabolize through biological methods due to the limitations of biocatalytic mechanisms. Nevertheless, cost, easy-to-operate and environmentally safe are some of the advantages over its counterpart. The present review comprehensively discusses the occurrence of PFAS, the state-of-the science of remediation technologies and approaches applied, and the remediation challenges. The article also focuses on the future research directions toward the development of effective methods for PFAS-contaminated site in-situ treatment.
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Affiliation(s)
- Bhim Sen Thapa
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Soumya Pandit
- Department of Life Sciences, School of Basic Sciences and Research, Sharda University, Greater Noida 201310, UP, India
| | - Rahul Kumar Mishra
- Department of Life Sciences, School of Basic Sciences and Research, Sharda University, Greater Noida 201310, UP, India
| | - Sanket Joshi
- Amity Institute of Microbial Technology, Amity University Rajasthan, Kant Kalwar, NH 11C, Jaipur, Rajasthan 303002, India
| | - Abubakr M Idris
- Department of Chemistry, College of Science, King Khalid University, Abha 62529, Saudi Arabia; Research Center for Advanced Materials Science (RCAMS), King Khalid University, Abha 62529, Saudi Arabia
| | - Tanmoy Roy Tusher
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA; Department of Environmental Science and Resource Management, Mawlana Bhashani Science and Technology University, Tangail 1902, Bangladesh.
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2
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Kirkwood-Donelson KI, Dodds JN, Schnetzer A, Hall N, Baker ES. Uncovering per- and polyfluoroalkyl substances (PFAS) with nontargeted ion mobility spectrometry-mass spectrometry analyses. SCIENCE ADVANCES 2023; 9:eadj7048. [PMID: 37878714 PMCID: PMC10599621 DOI: 10.1126/sciadv.adj7048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/22/2023] [Indexed: 10/27/2023]
Abstract
Because of environmental and health concerns, legacy per- and polyfluoroalkyl substances (PFAS) have been voluntarily phased out, and thousands of emerging PFAS introduced as replacements. Traditional analytical methods target a limited number of mainly legacy PFAS; therefore, many species are not routinely assessed in the environment. Nontargeted approaches using high-resolution mass spectrometry methods have therefore been used to detect and characterize unknown PFAS. However, their ability to elucidate chemical structures relies on generation of informative fragments, and many low concentration species are not fragmented in typical data-dependent acquisition approaches. Here, a data-independent method leveraging ion mobility spectrometry (IMS) and size-dependent fragmentation was developed and applied to characterize aquatic passive samplers deployed near a North Carolina fluorochemical manufacturer. From the study, 11 PFAS structures for various per- and polyfluorinated ether sulfonic acids and multiheaded perfluorinated ether acids were elucidated in addition to 36 known PFAS. Eight of these species were previously unreported in environmental media, and three suspected species were validated.
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Affiliation(s)
| | - James N. Dodds
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Astrid Schnetzer
- Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC,, USA
| | - Nathan Hall
- Department of Marine, Earth, and Atmospheric Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USA
| | - Erin S. Baker
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Shimizu MS, Garcia RS, Avery GB, Kieber RJ, Skrabal SA, Mead RN. Distribution of legacy and emerging per- and polyfluoroalkyl substances in riverine and coastal sediments of Southeastern North Carolina, USA. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:2119-2128. [PMID: 36200300 DOI: 10.1039/d2em00246a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The sediment distribution of per- and polyfluoroalkyl substances (PFAS) along a river to ocean transect was investigated. Samples were collected between September 2017 and October 2019 with targeted quantification of six legacy and replacement PFAS by LC-MS/MS. Total PFAS concentrations ranged from below the LOQ to 7.47 ng per g dry weight with PFOA, PFOS, HFPO-DA and PFMOAA the most frequently detected. Significant correlations (p < 0.05) were found between PFOS and HFPO-DA sedimentary concentration and percent organic carbon (% OC); however, PFOA and PFMOAA were not correlated with sediment % OC. This study highlights the occurrence of the replacement PFAS in sediments for the first time. Sediment extracts were screened for 18 additional PFAS compounds by high resolution mass spectrometry. A series of perfluorinated ether carboxylic acid and perfluorinated ether sulfonic acid with either one or two acidic functional groups were detected at various locations in the upper portion of the Cape Fear River. A series of chromatographically resolved isomers (C7F13O5S1; M-1) were detected and may be Nafion™ degradation products.
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Affiliation(s)
- Megumi S Shimizu
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
| | - Rosa S Garcia
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
| | - G Brooks Avery
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
| | - Robert J Kieber
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
| | - Stephen A Skrabal
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
| | - Ralph N Mead
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
- Earth and Ocean Sciences, University of North Carolina Wilmington, Wilmington, NC 28403, USA
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4
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Maiti TK, Singh J, Dixit P, Majhi J, Bhushan S, Bandyopadhyay A, Chattopadhyay S. Advances in perfluorosulfonic acid-based proton exchange membranes for fuel cell applications: A review. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2022.100372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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Kamat GA, Zamora Zeledón JA, Gunasooriya GTKK, Dull SM, Perryman JT, Nørskov JK, Stevens MB, Jaramillo TF. Acid anion electrolyte effects on platinum for oxygen and hydrogen electrocatalysis. Commun Chem 2022; 5:20. [PMID: 36697647 PMCID: PMC9814610 DOI: 10.1038/s42004-022-00635-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 01/20/2022] [Indexed: 01/28/2023] Open
Abstract
Platinum is an important material with applications in oxygen and hydrogen electrocatalysis. To better understand how its activity can be modulated through electrolyte effects in the double layer microenvironment, herein we investigate the effects of different acid anions on platinum for the oxygen reduction/evolution reaction (ORR/OER) and hydrogen evolution/oxidation reaction (HER/HOR) in pH 1 electrolytes. Experimentally, we see the ORR activity trend of HClO4 > HNO3 > H2SO4, and the OER activity trend of HClO4 [Formula: see text] HNO3 ∼ H2SO4. HER/HOR performance is similar across all three electrolytes. Notably, we demonstrate that ORR performance can be improved 4-fold in nitric acid compared to in sulfuric acid. Assessing the potential-dependent role of relative anion competitive adsorption with density functional theory, we calculate unfavorable adsorption on Pt(111) for all the anions at HER/HOR conditions while under ORR/OER conditions [Formula: see text] binds the weakest followed by [Formula: see text] and [Formula: see text]. Our combined experimental-theoretical work highlights the importance of understanding the role of anions across a large potential range and reveals nitrate-like electrolyte microenvironments as interesting possible sulfonate alternatives to mitigate the catalyst poisoning effects of polymer membranes/ionomers in electrochemical systems. These findings help inform rational design approaches to further enhance catalyst activity via microenvironment engineering.
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Affiliation(s)
- Gaurav Ashish Kamat
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - José A Zamora Zeledón
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | | | - Samuel M Dull
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Joseph T Perryman
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Jens K Nørskov
- Catalysis Theory Center, Department of Physics, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Michaela Burke Stevens
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA.
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
| | - Thomas F Jaramillo
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, CA, 94305, USA.
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA.
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Yamaguchi M. DFT Study on Side Chain Detachment of Perfluorosulfonic Acid Ionomers by Radical-Assisted Nucleophilic Attack of Water. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.109832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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7
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Robert M, El Kaddouri A, Perrin JC, Raya J, Lottin O. Time-resolved monitoring of composite Nafion™ XL membrane degradation induced by Fenton's reaction. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Zysler M, Klingbell T, Amos CD, Ferreira PJ, Zitoun D. Carbon supported Pt–Ni octahedral electrocatalysts as a model to monitor nickel corrosion and particle detachment. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00463h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pt–Ni oxygen reduction reaction catalyst are reacted with chelating agents to model their stability in a fuel cell. All chelating agents do show Ni dealloying and we discovered that amino-rich chelates do also detach the NPs from the carbon support.
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Affiliation(s)
- Melina Zysler
- Department of Chemistry and
- Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA)
- Bar-Ilan University
- Ramat Gan 5290002
- Israel
| | - Tal Klingbell
- Department of Chemistry and
- Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA)
- Bar-Ilan University
- Ramat Gan 5290002
- Israel
| | - Charles D. Amos
- Department of Advanced Electron Microscopy, Imaging, and Spectroscopy
- International Iberian Nanotechnology Laboratory (INL)
- Portugal
| | - Paulo J. Ferreira
- Department of Advanced Electron Microscopy, Imaging, and Spectroscopy
- International Iberian Nanotechnology Laboratory (INL)
- Portugal
- Materials Science and Engineering Program
- The University of Texas at Austin
| | - David Zitoun
- Department of Chemistry and
- Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA)
- Bar-Ilan University
- Ramat Gan 5290002
- Israel
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Frühwirt P, Kregar A, Törring JT, Katrašnik T, Gescheidt G. Holistic approach to chemical degradation of Nafion membranes in fuel cells: modelling and predictions. Phys Chem Chem Phys 2020; 22:5647-5666. [PMID: 32101187 DOI: 10.1039/c9cp04986j] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The state of health of polyfluorinated sulfonic-acid ionomer membranes (e.g. Nafion®) in low-temperature proton exchange membrane fuel cells (LT-PEMFCs) is negatively influenced by degradation phenomena occurring during their operation. As a consequence, the performance and durability of the membrane are decreased. In this article, we focus on simulating and predicting chemical membrane degradation phenomena using a holistic zero-dimensional kinetic framework. The knowledge of chemical degradation mechanisms is widely spread. We have collected and evaluated an extensive set of chemical mechanisms to achieve a holistic approach. This yields a set of 23 coupled chemical equations, which provide the whole cause and effect chain of chemical degradation in LT-PEMFCs (based on the Fenton reaction between Fe2+ and H2O2via the attack of hydroxyl radicals on the membrane, loss of ionomer moieties and emission of fluoride). Our kinetic framework allows the reproduction of experimentally accessible data such as fluoride emission rates and concentrations of ionomer moieties (from both in situ and ex situ tests). We present an approach, which allows estimations of the membrane lifetime based on fluoride emission rates. In addition, we outline the demetallation of Fe-N-C catalysts as a source of additional harmful iron species, which accelerate chemical membrane degradation. To demonstrate the expandability and versatility of the kinetic framework, a set of five chemical equations describing the radical scavenging properties of cerium agents is coupled to the main framework and its influence on membrane degradation is analysed. An automated solving routine for the system of coupled chemical equations on the basis of the chemical kinetic simulation tool COPASI has been developed and is freely accessible online ().
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Affiliation(s)
- Philipp Frühwirt
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
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10
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Katzenberg A, Chowdhury A, Fang M, Weber AZ, Okamoto Y, Kusoglu A, Modestino MA. Highly Permeable Perfluorinated Sulfonic Acid Ionomers for Improved Electrochemical Devices: Insights into Structure–Property Relationships. J Am Chem Soc 2020; 142:3742-3752. [DOI: 10.1021/jacs.9b09170] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Adlai Katzenberg
- Tandon School of Engineering, New York University, Brooklyn, NY 11201, United States
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Anamika Chowdhury
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, United States
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Minfeng Fang
- Tandon School of Engineering, New York University, Brooklyn, NY 11201, United States
| | - Adam Z. Weber
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Yoshiyuki Okamoto
- Tandon School of Engineering, New York University, Brooklyn, NY 11201, United States
| | - Ahmet Kusoglu
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Miguel A. Modestino
- Tandon School of Engineering, New York University, Brooklyn, NY 11201, United States
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11
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McCord J, Strynar M. Identification of Per- and Polyfluoroalkyl Substances in the Cape Fear River by High Resolution Mass Spectrometry and Nontargeted Screening. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4717-4727. [PMID: 30993978 PMCID: PMC7478245 DOI: 10.1021/acs.est.8b06017] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Ongoing chemical development in response to regulation of historical perfluorinated compounds, (i.e., perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)) has resulted in a proliferation of novel per- and polyfluorinated species. Screening and monitoring for these emerging chemicals benefit from a nontargeted approach due to a lack of necessary standards and a paucity of information about the replacement chemistries. In this paper, we apply nontargeted screening to the Cape Fear River of North Carolina, a fluorochemically impacted watershed. The continued presence of perfluorinated ether acids was confirmed, with a total of 37 unique chemical formulas comprising 58 isomers detected. Structural determination was carried out by LC-MS/MS to determine isomeric structures where possible. Novel structures determined included perfluorinated ether acid species containing two acidic sites, polyfluorinated ether acids containing a single hydrogenation, and previously unreported perfluorinated ether acids. Compounds identified by an initial nontargeted screen were monitored over repeated sampling to track long-term reductions in PFAS content during emission source control. Hierarchical clustering of the time course data was used to associate groups of chemicals based on their trends over time. Six clusters were identified and showed some similarity in chemical class; they are believed to represent the byproducts of different fluorochemical production lines.
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Affiliation(s)
- James McCord
- National Exposure Research Laboratory, U.S. Environmental Protection Agency , Oak Ridge Institute for Science and Education , Research Triangle Park , Durham , North Carolina 27711 , United States
| | - Mark Strynar
- National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , Durham , North Carolina 27711 , United States
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12
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Nishikawa H, Yano H, Inukai J, Tryk DA, Iiyama A, Uchida H. Effects of Sulfate on the Oxygen Reduction Reaction Activity on Stabilized Pt Skin/PtCo Alloy Catalysts from 30 to 80 °C. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:13558-13564. [PMID: 30378419 DOI: 10.1021/acs.langmuir.8b02945] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The effects of the concentration of H2SO4 ([H2SO4]), which is the major decomposition product of polymer electrolyte membranes during the operation of fuel cells, on the performance of stabilized Pt skin/PtCo alloy nanocatalysts supported on high-surface-area carbon (PtxAL-PtCo/C) were investigated. Kinetically controlled activities for the oxygen reduction reaction (ORR) and the H2O2 yields ( P(H2O2)) on the PtxAL-PtCo/C were examined based on hydrodynamic voltammograms in O2-saturated 0.1 M HClO4 + X M H2SO4 ( X = 0 to 5 × 10-2) by use of the channel flow double electrode method at temperatures between 30 and 80 °C. At X ≤ 10-6 (1 μM) and all temperatures examined, the apparent ORR rate constants kapp@0.85 V (per unit electrochemically active surface area) on PtxAL-PtCo/C at 0.85 V vs the reversible hydrogen electrode (RHE) were nearly identical with those in sulfate-free 0.1 M HClO4 and were at least twice as high as those on a commercial Pt/C catalyst (c-Pt/C). The values of kapp@0.85 V on both PtxAL-PtCo/C and c-Pt/C decreased linearly with log[H2SO4] in the concentration range 10-6 < X ≤ 5 × 10-2. The detrimental effect by H2SO4 was less pronounced on PtxAL-PtCo/C than on c-Pt/C at high temperatures; the kapp@0.85 V value at X = 5 × 10-2 on the former at 80 °C was maintained as high as 87%, whereas that of the latter was 66% (34% loss). The values of peroxide production percentage P(H2O2) on PtxAL-PtCo/C at 80 °C were nearly constant (ca. 0.22% at 0.76 V vs RHE) up to X = 5 × 10-2. These superior characteristics are ascribed to weakened adsorption of sulfate on the Pt skin surface, supported by DFT calculations, which provides the great advantage of robustness in the presence of impurities, maintaining active sites for the ORR during the PEFC operation.
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Affiliation(s)
| | - Hiroshi Yano
- Fuel Cell Nanomaterials Center , University of Yamanashi , 6-43 Miyamae-cho , Kofu 400-0021 , Japan
| | - Junji Inukai
- Fuel Cell Nanomaterials Center , University of Yamanashi , 6-43 Miyamae-cho , Kofu 400-0021 , Japan
| | - Donald A Tryk
- Fuel Cell Nanomaterials Center , University of Yamanashi , 6-43 Miyamae-cho , Kofu 400-0021 , Japan
| | - Akihiro Iiyama
- Fuel Cell Nanomaterials Center , University of Yamanashi , 6-43 Miyamae-cho , Kofu 400-0021 , Japan
| | - Hiroyuki Uchida
- Fuel Cell Nanomaterials Center , University of Yamanashi , 6-43 Miyamae-cho , Kofu 400-0021 , Japan
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Tsuneda T, Singh RK, Iiyama A, Miyatake K. Theoretical Investigation of the H 2O 2-Induced Degradation Mechanism of Hydrated Nafion Membrane via Ether-Linkage Dissociation. ACS OMEGA 2017; 2:4053-4064. [PMID: 31457706 PMCID: PMC6641634 DOI: 10.1021/acsomega.7b00594] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/18/2017] [Indexed: 06/10/2023]
Abstract
A H2O2-induced degradation mechanism is presented for the hydrated Nafion membrane proceeding through the dissociation of the ether linkages of the side chains. Although the durability of proton-exchange membrane fuel cells clearly depends on the degradation rate of the membrane, typically Nafion, the degradation mechanism still has not been resolved. It has often been assumed that the principal mode of degradation involves OH• radicals; in contrast, we show here that a H2O2-induced degradation mechanism is more likely. On the basis of state-of-the-art theoretical calculations and detailed comparison with experimental results, we present such a mechanism for the hydrated Nafion membrane, proceeding through the dissociation of the ether linkage of the side chains, with a relatively low activation energy. In this mechanism, (H2O)λHO3S-CF2-CF2-O-O-H (λ is the hydration number) is obtained as a key degradation fragment. Possible subsequent decomposition-reaction mechanisms are also elucidated for this fragment. The calculated vibrational spectra for the intermediates and products proposed in these mechanisms were found to be consistent with the experimental IR spectra. Further consideration of this H2O2-mediated degradation mechanism could greatly facilitate the search for ways to combat membrane degradation.
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Abstract
In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers' complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films are presented. Throughout, the impact of PFSA chemistry and side-chain is also discussed to present a broader perspective.
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Affiliation(s)
- Ahmet Kusoglu
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, MS70-108B, Berkeley, California 94720, United States
| | - Adam Z Weber
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, MS70-108B, Berkeley, California 94720, United States
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15
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Wong KH, Kjeang E. Mitigation of chemical membrane degradation in fuel cells: understanding the effect of cell voltage and iron ion redox cycle. CHEMSUSCHEM 2015; 8:1072-1082. [PMID: 25708935 DOI: 10.1002/cssc.201402957] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 06/04/2023]
Abstract
Chemical membrane degradation through the Fenton's reaction is one of the main lifetime-limiting factors for polymer-electrolyte fuel cells. In this work, a comprehensive, transient membrane degradation model is developed to capture and elucidate the complex in situ degradation mechanism. A redox cycle of iron ions is discovered within the membrane electrolyte assembly, which sustains the Fe(II) concentration and results in the most severe chemical degradation at open circuit voltage. The cycle strength is critically reduced at lower cell voltages, which leads to an exponential decrease in Fe(II) concentration and associated membrane degradation rate. When the cell voltage is held below 0.7 V, a tenfold reduction in cumulative fluoride release is achieved, which suggests that intermediate cell voltage operation would efficiently mitigate chemical membrane degradation and extend the fuel cell lifetime.
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Affiliation(s)
- Ka Hung Wong
- School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T0A3 (Canada), Fax: (+1) 778-782-7514
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16
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Ghelichi M, Melchy PÉA, Eikerling MH. Radically Coarse-Grained Approach to the Modeling of Chemical Degradation in Fuel Cell Ionomers. J Phys Chem B 2014; 118:11375-86. [DOI: 10.1021/jp506333p] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Mahdi Ghelichi
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
| | - Pierre-Éric Alix Melchy
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
| | - Michael H. Eikerling
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
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17
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Fechete R, Demco DE, Zhu X, Tillmann W, Möller M. Water states and dynamics in perfluorinated ionomer membranes by 1H one- and two-dimensional NMR spectroscopy, relaxometry, and diffusometry. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Ghassemzadeh L, Peckham TJ, Weissbach T, Luo X, Holdcroft S. Selective formation of hydrogen and hydroxyl radicals by electron beam irradiation and their reactivity with perfluorosulfonated acid ionomer. J Am Chem Soc 2013; 135:15923-32. [PMID: 24074044 DOI: 10.1021/ja408032p] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selective formation and reactivity of hydrogen (H(•)) and hydroxyl (HO(•)) radicals with perfluorinated sulfonated ionomer membrane, Nafion 211, is described. Selective formation of radicals was achieved by electron beam irradiation of aqueous solutions of H2O2 or H2SO4 to form HO(•) and H(•), respectively, and confirmed by ESR spectroscopy using a spin trap. The structure of Nafion 211 after reaction with H(•) or HO(•) was determined using calibrated (19)F magic angle spinning NMR spectroscopy. Soluble residues of degradation were analyzed by liquid and solid-state NMR. NMR and ATR-FTIR spectroscopy, together with determination of ion exchange capacity, water uptake, proton conductivity, and fluoride ion release, strongly indicate that attack by H(•) occurs at the tertiary carbon C-F bond on both the main and side chain; whereas attack by HO(•) occurs solely on the side chain, specifically, the α-O-C bond.
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Affiliation(s)
- Lida Ghassemzadeh
- Department of Chemistry, Simon Fraser University , 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6
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19
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Danilczuk M, Schlick S, Coms FD. Detection of Radicals by Spin Trapping ESR in a Fuel Cell Operating with a Sulfonated Poly(ether ether ketone) (SPEEK) Membrane. Macromolecules 2013. [DOI: 10.1021/ma401188u] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Marek Danilczuk
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols, Detroit, Michigan
48221, United States
| | - Shulamith Schlick
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols, Detroit, Michigan
48221, United States
| | - Frank D. Coms
- General Motors Electrochemical Energy Research Lab,
10 Carriage Street, Honeoye Falls, New York 14472, United States
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20
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Radice S, Oldani C, Merlo L, Rocchia M. Aquivion® PerfluoroSulfonic Acid ionomer membranes: A micro-Raman spectroscopic study of ageing. Polym Degrad Stab 2013. [DOI: 10.1016/j.polymdegradstab.2013.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Ghassemzadeh L, Holdcroft S. Quantifying the Structural Changes of Perfluorosulfonated Acid Ionomer upon Reaction with Hydroxyl Radicals. J Am Chem Soc 2013; 135:8181-4. [DOI: 10.1021/ja4037466] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lida Ghassemzadeh
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British
Columbia, Canada V5A1S6
| | - Steven Holdcroft
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British
Columbia, Canada V5A1S6
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22
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Collette FM, Thominette F, Mendil-Jakani H, Gebel G. Structure and transport properties of solution-cast Nafion® membranes subjected to hygrothermal aging. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2013.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Prabhakaran V, Arges CG, Ramani V. In situ fluorescence spectroscopy correlates ionomer degradation to reactive oxygen species generation in an operating fuel cell. Phys Chem Chem Phys 2013; 15:18965-72. [DOI: 10.1039/c3cp53919a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Wang Z, Tang H, Zhang H, Lei M, Chen R, Xiao P, Pan M. Synthesis of Nafion/CeO2 hybrid for chemically durable proton exchange membrane of fuel cell. J Memb Sci 2012. [DOI: 10.1016/j.memsci.2012.07.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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25
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A review of molecular-level mechanism of membrane degradation in the polymer electrolyte fuel cell. MEMBRANES 2012; 2:395-414. [PMID: 24958288 PMCID: PMC4021911 DOI: 10.3390/membranes2030395] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/18/2012] [Accepted: 06/27/2012] [Indexed: 11/21/2022]
Abstract
Chemical degradation of perfluorosulfonic acid (PFSA) membrane is one of the most serious problems for stable and long-term operations of the polymer electrolyte fuel cell (PEFC). The chemical degradation is caused by the chemical reaction between the PFSA membrane and chemical species such as free radicals. Although chemical degradation of the PFSA membrane has been studied by various experimental techniques, the mechanism of chemical degradation relies much on speculations from ex-situ observations. Recent activities applying theoretical methods such as density functional theory, in situ experimental observation, and mechanistic study by using simplified model compound systems have led to gradual clarification of the atomistic details of the chemical degradation mechanism. In this review paper, we summarize recent reports on the chemical degradation mechanism of the PFSA membrane from an atomistic point of view.
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26
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Wood TJ, Badyal JPS. Pulsed plasmachemical deposition of highly proton conducting composite sulfonic acid-carboxylic acid films. ACS APPLIED MATERIALS & INTERFACES 2012; 4:1675-1682. [PMID: 22409149 DOI: 10.1021/am2018207] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Graft polymerization of sulfonic acid monomers onto structurally well-defined pulsed plasma poly(maleic anhydride) layers yields a composite carboxylic acid-sulfonic acid network. These bifunctional films are shown to exhibit high proton conductivity (125 mS cm(-1)) as well as good stability in water.
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Affiliation(s)
- T J Wood
- Department of Chemistry, Science Laboratories, Durham University, Durham DH1 3LE, England, United propylKingdom
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27
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Danilczuk M, Lancucki L, Schlick S, Hamrock SJ, Haugen GM. In-Depth Profiling of Degradation Processes in a Fuel Cell: 2D Spectral-Spatial FTIR Spectra of Nafion Membranes. ACS Macro Lett 2012; 1:280-285. [PMID: 35578523 DOI: 10.1021/mz200100s] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present in-depth profiling by micro FTIR of cross sections for Nafion 115 membranes in membrane-electrode assemblies (MEAs) degraded during 52 or 180 h at open circuit voltage (OCV) conditions, 90 °C and 30% relative humidity. Analysis of optical images showed highly degraded zones in both MEAs. Corresponding 2D FTIR spectral-spatial maps indicated that C-H and C═O groups are generated during degradation. The highest band intensities for both groups appeared at a depth of 82 μm from the cathode in the MEA degraded for 180 h; the same bands were present but less intense at a depth of 22 μm from the cathode. Degradation at these depths is most likely associated with the location of the Pt band formed from Pt dissolution and migration into the membrane. The two degradation bands, C═O and C-H, appeared at the same depths from the cathode, 82 and 22 μm, suggesting that they are generated by a common mechanism or intermediate. This result is rationalized by a very important first reaction: Abstraction of a fluorine atom from the polymer main chain and side chain by hydrogen atoms, H•. This step is expected to cause main chain and side chain scission and to generate RF-CF2• radicals that can react with H2O2, H2O, and H2 to produce both -COOH and RCF2H groups.
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Affiliation(s)
- Marek Danilczuk
- Department of Chemistry
and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221,
United States
| | - Lukasz Lancucki
- Department of Chemistry
and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221,
United States
| | - Shulamith Schlick
- Department of Chemistry
and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221,
United States
| | - Steven J. Hamrock
- 3M Fuel Cell Components Group, 3M Center, St. Paul, Minnesota 55144, United
States
| | - Gregory M. Haugen
- 3M Fuel Cell Components Group, 3M Center, St. Paul, Minnesota 55144, United
States
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28
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Spulber M, Schlick S. Fragmentation of Perfluorinated Membranes Used in Fuel Cells: Detecting Very Early Events by Selective Encapsulation of Short-Lived Fragments in β-Cyclodextrin. J Phys Chem B 2011; 115:12415-21. [PMID: 21923141 DOI: 10.1021/jp208177s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Mariana Spulber
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols, Detroit, Michigan 48221, United States
| | - Shulamith Schlick
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols, Detroit, Michigan 48221, United States
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29
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Ogata Y, Iwano M, Mogi T, Makita Y. Aggregation behavior of amphiphilic random copolymer of 2-(acrylamido)-2-methylpropanesulfonic acid and tris(trimethylsiloxy)silylpropylmethacrylate in aqueous solution. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/polb.22354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Faraj M, Elia E, Boccia M, Filpi A, Pucci A, Ciardelli F. New anion conducting membranes based on functionalized styrene-butadiene-styrene triblock copolymer for fuel cells applications. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/pola.24781] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Bose S, Kuila T, Nguyen TXH, Kim NH, Lau KT, Lee JH. Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges. Prog Polym Sci 2011. [DOI: 10.1016/j.progpolymsci.2011.01.003] [Citation(s) in RCA: 687] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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32
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Xu A, Zhao J, Yuan WZ, Li H, Zhang H, Wang L, Zhang Y. Tetrafluoroethylene Copolymers with Sulfonyl Fluoride Pendants: Syntheses in Supercritical Carbon Dioxide, Polymerization Behaviors, and Properties. MACROMOL CHEM PHYS 2011. [DOI: 10.1002/macp.201100126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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33
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Patil Y, Kulkarni S, Mauritz KA. In situ grown titania composition for optimal performance and durability of Nafion® fuel cell membranes. J Appl Polym Sci 2011. [DOI: 10.1002/app.31500] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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34
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Ghassemi H, Schiraldi DA, Zawodzinski TA, Hamrock S. Poly(arylene ether)s with Pendant Perfluoroalkyl Sulfonic Acid Groups as Proton-Exchange Membrane Materials. MACROMOL CHEM PHYS 2011. [DOI: 10.1002/macp.201000650] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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35
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Durability of PEM Fuel Cell Membranes. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/978-0-387-98068-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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36
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Vogel B, Dilger H, Roduner E. Rapid Radical Degradation Test of Polyaromatic Fuel Cell Membranes by Electron Paramagnetic Resonance. Macromolecules 2010. [DOI: 10.1021/ma1006073] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Barbara Vogel
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Herbert Dilger
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Emil Roduner
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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37
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Danilczuk M, Perkowski AJ, Schlick S. Ranking the Stability of Perfluorinated Membranes Used in Fuel Cells to Attack by Hydroxyl Radicals and the Effect of Ce(III): A Competitive Kinetics Approach Based on Spin Trapping ESR. Macromolecules 2010. [DOI: 10.1021/ma1001386] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marek Danilczuk
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221
| | - Andrew J. Perkowski
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221
| | - Shulamith Schlick
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221
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38
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Chow CF, Roy VAL, Ye Z, Lam MHW, Lee CS, Lau KC. Novel high proton conductive material from liquid crystalline 4-(octadecyloxy)phenylsulfonic acid. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm00523a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Danilczuk M, Schlick S, Coms FD. Cerium(III) as a Stabilizer of Perfluorinated Membranes Used in Fuel Cells: In Situ Detection of Early Events in the ESR Resonator. Macromolecules 2009. [DOI: 10.1021/ma9017108] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Marek Danilczuk
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221
| | - Shulamith Schlick
- Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221
| | - Frank D. Coms
- General Motors Electrochemical Energy Research Lab, 10 Carriage Street, Honeoye Falls, New York 14472
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40
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Patil Y, Mauritz KA. Durability enhancement of Nafion® fuel cell membranes via in situ sol-gel-derived titanium dioxide reinforcement. J Appl Polym Sci 2009. [DOI: 10.1002/app.30195] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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41
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42
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Danilczuk M, Coms FD, Schlick S. Visualizing chemical reactions and crossover processes in a fuel cell inserted in the ESR resonator: detection by spin trapping of oxygen radicals, nafion-derived fragments, and hydrogen and deuterium atoms. J Phys Chem B 2009; 113:8031-42. [PMID: 19453175 DOI: 10.1021/jp901597f] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We present experiments in an in situ fuel cell (FC) inserted in the resonator of the ESR spectrometer that offered the ability to observe separately processes at anode and cathode sides and to monitor the formation of HO and HOO radicals, H and D atoms, and radical fragments derived from the Nafion membrane. The presence of the radicals was determined by spin-trapping electron spin resonance (ESR) with 5,5-dimethylpyrroline N-oxide (DMPO) as a spin trap. The in situ FC was operated at 300 K with a membrane-electrode assembly (MEA) based on Nafion 117 and Pt as catalyst, at closed and open circuit voltage conditions, CCV and OCV, respectively. Experiments with H(2) or D(2) at the anode and O(2) at the cathode were performed. The DMPO/OH adduct was detected only at the cathode for CCV operation, suggesting generation of hydroxyl radicals from H(2)O(2) formed electrochemically via the two-electron reduction of oxygen. The DMPO/OOH adduct, detected in this study for the first time in a FC, appeared at the cathode and anode for OCV operation, and at the cathode after CCV FC operation of >or=2 h. These results were interpreted in terms of electrochemical generation of HOO at the cathode (HO + H(2)O(2) --> H(2)O + HOO) and its chemical generation at the anode from hydrogen atoms and crossover oxygen (H + O(2) --> HOO). DMPO/H and DMPO/D adducts were detected at the anode and cathode sides, for CCV and OCV operation; H and D are aggressive radicals capable of abstracting fluorine from the tertiary carbon in the polymer membrane chain and of leading to chain fragmentation. Carbon-centered radical (CCR) adducts were detected at the cathode after CCV FC operation; weak CCR signals were also detected at the anode. CCRs can originate only from the Nafion membranes, and their presence indicates membrane fragmentation. Taken together, this study has demonstrated that FC operation involves processes such as gas crossover, reactions at the catalyst surface, and possible attack of the membrane by reactive H or D that do not occur in ex situ experiments in the laboratory, thus implying different mechanistic pathways in the two types of experiments.
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Affiliation(s)
- Marek Danilczuk
- Department of Chemistry, University of Detroit Mercy, 4001 West McNichols Road, Detroit, Michigan 48221, USA
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43
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Kabasawa A, Saito J, Miyatake K, Uchida H, Watanabe M. Effects of the decomposition products of sulfonated polyimide and Nafion membranes on the degradation and recovery of electrode performance in PEFCs. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2008.11.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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44
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Schönberger F, Kerres J, Dilger H, Roduner E. EPR spectroscopic investigation of radical-induced degradation of partially fluorinated aromatic model compounds for fuel cell membranes. Phys Chem Chem Phys 2009; 11:5782-95. [DOI: 10.1039/b817070c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Volkov VV, Mchedlishvili BV, Roldugin VI, Ivanchev SS, Yaroslavtsev AB. Membranes and nanotechnologies. ACTA ACUST UNITED AC 2008. [DOI: 10.1134/s1995078008110025] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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46
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Ivanchev SS. Fluorinated proton-conduction nafion-type membranes, the past and the future. RUSS J APPL CHEM+ 2008. [DOI: 10.1134/s1070427208040010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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47
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H[sub 2]O[sub 2] Release during Oxygen Reduction Reaction on Pt Nanoparticles. ACTA ACUST UNITED AC 2008. [DOI: 10.1149/1.2978090] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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