Article
Polymer Science
Stefania Siracusano, Fausta Giacobello, Stefano Tonella, Claudio Oldani, Antonino S. Arico
Summary: A Ce-radical scavenger-based PFSA Aquivion(R) membrane was developed and evaluated for PEM electrolyser applications. The manufacturing method of the membrane significantly influenced the interfacial properties and stability.
Article
Engineering, Chemical
Santiago P. Fernandez Bordin, Heber E. Andrada, Alejo C. Carreras, Gustavo Castellano, Ralf Schweins, Gabriel J. Cuello, Claudia Mondelli, Victor M. Galvan Josa
Summary: Fuel cells play a strategic role in the global energy system, with a particular focus on eco-cars to reduce CO2 emissions. This study examines the characteristics of commercial polymeric proton exchange membranes using techniques such as small angle neutron scattering for optimization.
JOURNAL OF MEMBRANE SCIENCE
(2021)
Article
Chemistry, Physical
Yeong Ho Lee, Jin Young Park, Jejun Choi, In Seop Lim, Songhun Cha, Yoo Il Lee, Min Soo Kim
Summary: This study investigates the durability and degradation issues of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) used in high-humidity environments and small stack sizes. A method for improving the uniformity of current density distribution and reducing degradation in PEMFCs is proposed by periodically controlling the flow direction. The proposed method delays degradation and improves the uniformity of current density distribution and voltage differences between cells in the stack, showing potential for enhancing the durability and performance of PEMFCs in specific applications.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Electrochemistry
ChulOong Kim, Ivy Wu, Mei-Chen Kuo, Dominic J. Carmosino, Ethan W. Bloom, Soenke Seifert, David A. Cullen, Phuc Ha, Matthew J. Lindell, Ruichun Jiang, Craig S. Gittleman, Michael A. Yandrasits, Andrew M. Herring
Summary: Commercial proton exchange membrane heavy-duty fuel cell vehicles require a more durable composite membrane that can potentially conduct protons. We developed a composite membrane incorporating silicotungstic heteropoly acid (HPA) and other materials, which showed less swelling, more hydrophobic properties, and higher crystallinity than conventional membranes. This composite membrane demonstrated a proton conductivity of 0.130 +/- 0.03 S cm(-1) at 80 degrees C and 95% RH, and survived more than 800 hours under accelerated stress test conditions.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Energy & Fuels
Dedar Emad Hussin, Yagmur Budak, Yilser Devrim
Summary: In this study, PBI/BN composite membranes were prepared for high-temperature PEM fuel cells, with a study on the loading of BN and various characterizations and performance tests conducted. The PBI/BN-2.5 membrane showed the highest conductivity at 180 degrees Celsius, indicating potential for high-temperature PEMFC applications.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Review
Chemistry, Multidisciplinary
Nedjeljko Seselj, Silvia M. M. Alfaro, Eftychia Bompolaki, Lars N. N. Cleemann, Tomas Torres, Kobra Azizi
Summary: The constant increase in global emission standards has led to the importance of fuel cell (FC) technology. Research in the past two decades has focused on developing more active catalysts for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC) and improving their durability. Two main approaches have been suggested: alloying platinum (Pt) with low-cost transition metals to reduce Pt usage, and developing novel catalyst supports to enhance metal particle anchoring and inhibit corrosion phenomena. This comprehensive review details the recent development of platinum group metal (PGM) and platinum group metal free (PGM-free) catalysts, as well as alternative carbon (C) supports for HT-PEMFCs.
ADVANCED MATERIALS
(2023)
Review
Biochemistry & Molecular Biology
Mohammad Ebrahimi, Wojciech Kujawski, Kateryna Fatyeyeva, Joanna Kujawa
Summary: This review discusses the utilization of ionic liquids (ILs) in middle and high temperature polymer electrolyte membrane fuel cells, covering their structure, properties, synthesis, and the issue of leaching. Key studies are evaluated to provide updated information on the progress in this field.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Chemistry, Multidisciplinary
Daniel Ilk, Viktoria Frick, Christopher Haenel, Thomas Schiestel, Michael Schoemaker, Holger Kraus, Harry E. Hoster
Summary: Membrane humidifiers are commonly used to improve the performance and lifespan of polymer electrolyte membrane fuel cells. This study tested five industrial humidifier membranes against five pollutant gases to evaluate their water transfer capabilities before and after exposure. The results showed that certain materials, such as polyimides and fluopolymers, were degraded by ozone, leading to decreased mechanical stability, while polysulfone membranes exhibited a decline in water transfer over time. The decline in water transfer could be attributed to physical degradation of the polymer rather than the presence of harmful gases. PFSA membranes were found to be particularly sensitive to ammonia.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2023)
Article
Automation & Control Systems
Jiyuan Kuang, Jianfeng Lv, Wenbo Hao, Xinpo Lin, Dongdong Zhao, Imad Matraji, Patrick Muhl, Jianxing Liu
Summary: This paper focuses on addressing the air supply problem for fuel cells. A fixed-time observer is proposed to reconstruct the oxygen excess ratio, and a cascaded double-loop controller is introduced to regulate the oxygen excess ratio to the optimal value within a prescribed short time. Hardware in-loop experiments validate the advantages of the proposed method over conventional finite-time control techniques.
Article
Chemistry, Multidisciplinary
Tanya Agarwal, Santosh Adhikari, Siddharth Komini Babu, Ajay K. Prasad, Suresh G. Advani, Rodney L. Borup
Summary: Researchers have found that ellagic acid, a bio-sourced organic antioxidant, enhances the chemical durability of perfluorosulfonic acid (PFSA) membranes. When incorporated with cerium, ellagic acid increases the durability of PFSA membranes by at least 80%, which is 2.5 times higher than when ellagic acid is incorporated alone.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Audrey K. Taylor, Colby Smith, K. C. Neyerlin
Summary: Membrane electrode assemblies (MEAs) are prone to pin-hole formation during hot-press lamination, resulting in crossover of hydrogen (H2) fuel and failure of fuel cells. In this study, a calendering technique was used to flatten stray fibers and reduce pin-hole formation in MEAs. Accelerated stress tests showed that the calendered MEAs exhibited a 77% improvement in lifetime compared to as-fabricated MEAs.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Michael Obermaier, Krzysztof Jozwiak, Markus Rauber, Andreas Bauer, Christina Scheu
Summary: The knowledge gained from fuel cell degradation analysis is critical for achieving durability targets and commercializing polymer electrolyte membrane fuel cells, depending on the dominant degradation mode. This study systematically investigates four potential methods for detecting pinholes in the polymer membrane. Detection limits, material system impacts, and other relevant factors are discussed to optimize defect detection and make recommendations for practical application.
JOURNAL OF POWER SOURCES
(2021)
Article
Nanoscience & Nanotechnology
Hyunsik Oh, Byungrak Son, Sangaraju Shanmugam
Summary: When operating under low humidity, the proton conductivity of the polymer electrolyte membrane fuel cell (PEMFC) decreases, affecting its performance. Introducing appropriate additives, such as the multi-metal oxide CZTO, to the membrane and catalyst layer can prevent membrane degradation and significantly improve the performance of proton exchange membrane fuel cells. The Nafion-CZTO membrane showed enhanced power densities and improved durability compared to commercial Nafion membranes due to the high proton conductivity and radical scavenging properties of CZTO.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Hyoung Jun Lim, Geonwoo Kim, Gun Jin Yun
Summary: In this study, the chemo-mechanically coupled behavior of Nafion212 is investigated using multiphysics modeling and experimental validation. The degradation of perfluorosulfonic acid (PFSA) membrane, which plays a critical role in fuel cell performance and durability, is quantitatively estimated by measuring fluoride release. The nonlinear behavior of the PFSA membrane in tensile testing is modeled using J(2) plasticity-based material modeling, and the material parameters are characterized based on fluoride release levels. A pinhole growth model is adopted to investigate the life prediction of the membrane, and the validation is conducted by comparing it with the accelerated stress test (AST).
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Energy & Fuels
Qian Zhang, Mathias Schulze, Pawel Gazdzicki, K. Andreas Friedrich
Summary: This study analyzed the impact of three recovery procedures on the performance of polymer electrolyte membrane fuel cells. The research found that these procedures can effectively recover performance losses at high current densities, but show significant differences at lower current densities. The JRC protocol recovers kinetic losses by reducing the cathode potential and fuel cell temperature, while the DOE protocol has relatively poorer recovery effects.
Article
Chemistry, Applied
Divakar R. Aireddy, Amitava Roy, David A. Cullen, Kunlun Ding
Summary: Supported Na-Mn-W oxides on titanate nanowires were found to have similar catalytic performance as the commonly studied MnOx/Na2WO4/SiO2 catalyst, with a synergistic effect between MnOx and WOx sites. The titanate support not only acts as a reservoir for alkali metals, but also stabilizes isolated MnOx species, contributing to the high selectivity toward C2+ products and suppressed COx formation.
Article
Chemistry, Physical
Luigi Osmieri, Yanghua He, Hoon T. Chung, Geoffrey McCool, Barr Zulevi, David A. Cullen, Piotr Zelenay
Summary: Anion exchange membrane water electrolysis is an attractive technology for low-cost generation of green hydrogen by combining the use of noble metal-free catalysts with pure water feed. By addressing drawbacks of other electrolysis technologies, it has the potential to replace them.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Xiang Lyu, Tim Van Cleve, Erica Young, Jianlin Li, Haoran Yu, David A. Cullen, K. C. Neyerlin, Alexey Serov
Summary: Proton exchange membrane fuel cells (PEMFCs) powered by green hydrogen (H2) are a promising alternative to traditional hydrocarbon-fueled power generators. However, further improvements are needed in efficiency, durability, and low-cost production for widespread adoption. Most strategies to improve PEMFC electrodes utilize single material sets, but anisotropic electrode structures with locally tunable properties may offer enhanced performance due to improved transport.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Leiming Hu, Tim Van Cleve, Haoran Yu, Jae Hyung Park, Nancy Kariuki, A. Jeremy Kropf, Rangachary Mukundan, David A. Cullen, Deborah J. Myers, K. C. Neyerlin
Summary: The degradation of polymer electrolyte membrane fuel cells (PEMFCs) catalyst layers for heavy-duty vehicles was studied using a catalyst-specific accelerated stress test (AST). The PtCo/HSC catalyst showed better initial mass activity, larger initial mass transport loss, and faster degradation compared to a-Pt/HSC and Pt/HSC catalysts. Pt dissolution resulted in ECSA losses, either by catalyst particle growth or redeposition in the membrane.
JOURNAL OF POWER SOURCES
(2023)
Article
Electrochemistry
ChulOong Kim, Ivy Wu, Mei-Chen Kuo, Dominic J. Carmosino, Ethan W. Bloom, Soenke Seifert, David A. Cullen, Phuc Ha, Matthew J. Lindell, Ruichun Jiang, Craig S. Gittleman, Michael A. Yandrasits, Andrew M. Herring
Summary: Commercial proton exchange membrane heavy-duty fuel cell vehicles require a more durable composite membrane that can potentially conduct protons. We developed a composite membrane incorporating silicotungstic heteropoly acid (HPA) and other materials, which showed less swelling, more hydrophobic properties, and higher crystallinity than conventional membranes. This composite membrane demonstrated a proton conductivity of 0.130 +/- 0.03 S cm(-1) at 80 degrees C and 95% RH, and survived more than 800 hours under accelerated stress test conditions.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Electrochemistry
Krysta Waldrop, John J. Slack, Cenk Gumeci, Javier Parrondo, Nilesh Dale, Kimberly Shawn Reeves, David A. Cullen, Karren L. More, Peter N. Pintauro
Summary: MEA with nanofiber mat electrodes containing Pt/C catalyst and Nafion binder were fabricated and evaluated. The electrodes were prepared by electrospinning a solution of catalyst powder, salt-form Nafion, and a carrier polymer. MEAs with anode/cathode catalyst loadings of 0.1 mg(Pt) cm(-2) each and a Nafion 211 membrane demonstrated high power at both high and low RH conditions in H-2/air fuel cell tests. The presence of nm-size pores within the fibers trapped water via capillary condensation, maintaining high proton conductivity of the Nafion binder.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Jeonghoon Lim, Yu Chen, David A. Cullen, Seung Woo Lee, Thomas P. Senftle, Marta C. Hatzell
Summary: By controlling the copper surface coverage, palladium nanocubes as electrocatalysts can effectively reduce nitrate (NO3-) and increase the selectivity for the reduction of nitrite (NO2-) to N2 or NH4+. Partial copper-coated Pd nanocubes can reduce 95% of NO3- and have 89% selectivity for NO2- reduction over 20 cycles (80 h). Complete copper-covered Pd nanocubes can reduce about 99% of NO3- and selectively reduce NO2- to NH4+ with a 70% selectivity over 20 cycles (80 h).
Article
Electrochemistry
Kaur Muuli, Xiang Lyu, Marek Mooste, Maike Kaarik, Barr Zulevi, Jaan Leis, Haoran Yu, David A. Cullen, Alexey Serov, Kaido Tammeveski
Summary: In this study, Fe-N-C catalysts were prepared at a kilogram scale using the commercial VariPoreTM method, and the effect of synthesis conditions on the catalyst performance at ZAB air electrode was investigated. The results showed that the PA-450-HT catalyst exhibited excellent electrocatalytic activity for the oxygen reduction reaction (ORR) and was the most suitable catalyst for primary ZAB, with a galvanostatic polarization discharge peak power density of 149 mW cm-2, outperforming commercial Pt-Ru/C catalysts. Additionally, the NCB-600-HT catalyst displayed outstanding ORR and OER reversibility, with a half-wave potential of 0.87 V vs. RHE and a Delta E value of 0.81 V, and exhibited excellent charge-discharge cycling durability similar to NCB-550-LT for the secondary ZAB. This study reported for the first time the mass production of outstanding bifunctional Fe-N-C catalysts for rechargeable ZAB.
ELECTROCHIMICA ACTA
(2023)
Article
Chemistry, Physical
D. P. Leonard, S. Komini Babu, J. S. Baxter, H. M. Meyer, D. A. Cullen, R. L. Borup
Summary: The high production cost of gas diffusion layer (GDL) in proton exchange membrane fuel cells is mainly due to the use of polyacrylonitrile (PAN) fibers. This study examines the performance of inexpensive natural fiber-based papers and fabric as GDLs, and the improvements achieved by incorporating a microporous layer, gas-phase hydrophobic treatment, and densification. The resulting GDLs demonstrate comparable performance to the commercial baseline GDL and highlight the potential of reducing GDL manufacturing costs.
JOURNAL OF POWER SOURCES
(2023)
Article
Chemistry, Physical
Deng-Bing Li, Sabin Neupane, Sandip S. Bista, Chuanxiao Xiao, Abasi Abudulimu, Manoj K. Jamarkattel, Adam B. Phillips, Michael J. Heben, Jonathan D. Poplawsky, David A. Cullen, Chun-Sheng Jiang, Randall J. Ellingson, Yanfa Yan
Summary: Our previous work has shown that the formation of a penternary cadmium chalcogenide Cd(O,S,Se,Te) region can reduce front interface recombination in Cd(Se,Te)-based thin-film solar cells. In this work, we demonstrate that managing oxygen during device fabrication is crucial for forming this region. Improper oxygen management leads to low device performance due to the formation of a photoinactive Cd(S,Se) region and reduced absorber quality. Additionally, we investigate carrier transport and collection properties to understand the mechanisms resulting in improved efficiencies approaching 20%.
ACS ENERGY LETTERS
(2023)
Article
Polymer Science
Sunilkumar Khandavalli, Yingying Chen, Nisha Sharma-Nene, Kashyap Sundara Rajan, Samrat Sur, Jonathan P. Rothstein, Kimberley S. S. Reeves, David A. A. Cullen, K. C. Neyerlin, Scott A. A. Mauger, Michael Ulsh
Summary: We investigated the effect of alcohol fraction in a binary water-alcohol solvent mixture on the rheological properties and fiber formation of poly(acrylic acid) in electrospinning. We found that the addition of alcohol induces association/aggregation of the polymer, which affects its viscosity and elasticity. The presence of alcohol also stabilizes the jets/filaments during electrospinning, resulting in improved fiber formation.
JOURNAL OF POLYMER SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
X. Lyu, T. Zhang, Z. Li, C. J. Jafta, A. Serov, I. -H. Hwang, C. Sun, D. A. Cullen, J. Li, J. Wu
Summary: This study investigates the effect of trace Cu loading on metal-free catalysts for CO/CO2 reduction reactions (CORR). It is found that increasing Cu loading switches the selectivity from C1 (CH4) to C2 products in CORR. At a Cu loading of 2.5 mu g/cm2, the Faradaic efficiency of CH4 in CORR decreased from 62% to 52% for C2 products. Further increasing the atomic Cu loading to 3.8 mu g/cm2 promotes the Faradaic efficiency of C2 products to 78%. CO2RR requires higher Cu loading than CORR to switch the selectivity from C1 to C2 products. This study clarifies the distinct impact of trace Cu on the activity/selectivity between CORR and CO2RR.
MATERIALS TODAY CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
J. David Arregui-Mena, Philip D. Edmondson, David Cullen, Samara Levine, Cristian Contescu, Yutai Katoh, Nidia Gallego
Summary: In the 1960s, the feasibility of molten salt reactors for civil applications was demonstrated by the Molten Salt Reactor Experiment using CGB graphite as the fast neutron moderator. Additional impregnation steps were taken to reduce molten salt ingression, but little information has been published about the microstructure or sealant of this graphite grade. The study presents advanced microscopy results and investigates the sealing technology of legacy material from the Molten Salt Reactor Experiment, providing insights for potential reutilization in modern reactors.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Qing Gong, Hong Zhang, Haoran Yu, Sungho Jeon, Yang Ren, Zhenzhen Yang, Cheng-Jun Sun, Eric A. Stach, Alexandre C. Foucher, Yikang Yu, Matthew Smart, Gabriel M. Filippelli, David A. Cullen, Ping Liu, Jian Xie
Summary: Researchers have developed a simple method to deposit sub-3-nm L10-PtM nanoparticles onto carbon supports, resulting in improved Pt utilization and mass transport in polymer electrolyte membrane fuel cells. This approach achieved excellent oxygen reduction reaction activity, high power density, and durability, meeting the targets set by the Department of Energy.
Article
Nanoscience & Nanotechnology
Kui Li, Lei Ding, Zhiqiang Xie, Gaoqiang Yang, Shule Yu, Weitian Wang, David A. Cullen, Harry M. Meyer III, Guoxiang Hu, Panchapakesan Ganesh, Thomas R. Watkins, Feng-Yuan Zhang
Summary: Electrochemical conversion of nitrogen to green ammonia is hindered by the lack of efficient electrocatalysts. In this study, a cost-effective bimetallic Ru-Cu mixture catalyst in a nanosponge architecture was designed. The optimized Ru0.15Cu0.85 NS catalyst exhibited impressive N2RR performance and superior stability, surpassing monometallic Ru and Cu nanostructures. This work contributes to the design of efficient electrocatalysts for ambient electrochemical ammonia production.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Polymer Science
Tetsu Sato, Mariko Takahashi, Takeshi Saito, Masahito Toyonaga, Itsuo Tanuma, Rie Yamada, Satoru Hosoda
Summary: An automatic evaluation system for photooxidation has been developed and successfully applied to assess the photo-OIT of LDPE samples containing photooxidation stabilizers. The system allows independent setting of various measurement conditions and provides detailed information on the photooxidation process.
POLYMER DEGRADATION AND STABILITY
(2024)
Article
Polymer Science
Zongzheng Zuo, Shuxue Zhou
Summary: In this study, three fluoroalkyl trimethoxysilane (FATMS) additives with different chain lengths were incorporated into a two-component polyurethane clearcoat to improve its hydrophobic durability. The coatings modified with FATMS maintained their surface hydrophobicity under various conditions, but quickly lost it when exposed to both UV irradiation and/or high temperature with water. The results suggest that the FATMS route is more suitable for indoor applications at room temperature.
POLYMER DEGRADATION AND STABILITY
(2024)
Article
Polymer Science
Song Li, Feng Zhao, Xueya Wang, Zhihua Liu, Jingze Guo, Yutong Li, Shuangmei Tan, Zhenxiang Xin, Shuai Zhao, Lin Li
Summary: Green flame retardants have garnered attention for their environmental friendliness, but current options fall short in achieving high flame retardancy for flammable polymers and maintaining environmental protection. This study takes a two-pronged approach to address flame retardants and the flame-retardant process. An eco-friendly bio-based synergistic flame retardant (PAU), synthesized using phytic acid (PA) and urea (U), is used to create a flame retardant coating that can be directly applied to any surface shape using polydopamine as an adhesive. The resulting EPS-PAU exhibits excellent flame retardancy, smoke suppression, and light weight while only slightly increasing the density.
POLYMER DEGRADATION AND STABILITY
(2024)