bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionomer Impact on Oxygen Evolution Reaction Activity and Kinetics for Ir-Based Catalysts
Authors: Li Zhao , Wang Xiaoping , Kariuki Nancy N. , Park Jaehyung , Myers Deborah J. 
Published: December 2024

Renewable hydrogen generation using the low-temperature proton-exchange membrane water electrolyzer (PEMWE) represents a crucial technology for achieving global zero-carbon emissions. Iridium oxide (IrOx) stands out as a primary platinum group metal catalyst for the anode in electrochemical water splitting due to a balance in activity and stability in acidic environments.1 However, the anode catalyst performance is still predominately hampered by the sluggish kinetics of the oxygen evolution reaction (OER) compared to the hydrogen evolution reaction (HER) at the Pt cathode.2 Therefore,understanding the factors influencing the OER kinetics of Ir-based catalysts is essential for developing strategies to achieve high OER activity in the PEMWE anode electrocatalysts. This presentation will delve into our investigation of how the perfluorosulfonic acid (PFSA) binder affects the anode catalyst OER behaviors, specifically the corresponding kinetics and activity of two commercial Ir-based OER catalysts, IrOx from Alfa Aesar and TiO2-decorated IrOx (IrTiOx) from Umicore, as a function of the PFSA ionomer-to-catalyst (I/C) ratio. We combined the cavity microelectrode (CME) technique, which offers a direct approach to study OER kinetics without the ionomer,3 with the rotating disc electrode (RDE) technique, which allows to assess the impact of PFSA on OER kinetics and activity at varied I/C ratios in an acidic electrolyte. The study provided valuable insights into ionomer dependent OER mechanisms, elucidating the intricate interactions among the ionomer, catalyst, and reaction intermediates.
Acknowledgements
This research is supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the H2NEW Consortium. Argonne National Laboratory is managed by the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357.
Reference

S. M. Alia, M.-A. Ha, G. C. Anderson, C. Ngo, S. Pylypenko and R. E. Larsen, Journal of The Electrochemical Society, 2019, 166, F1243.

E. Oakton, D. Lebedev, M. Povia, D. F. Abbott, E. Fabbri, A. Fedorov, M. Nachtegaal, C. Copéret and T. J. Schmidt, Acs Catalysis, 2017, 7, 2346-2352.

J. Behnken, M. Yu, X. Deng, H. Tüysüz, C. Harms, A. Dyck and G. Wittstock, ChemElectroChem, 2019, 6, 3460-3467.
Mechanical Durability of Water Electrolysis Membranes in a Liquid Environment Under Differential Pressure Mode
Authors: Ueda Eijun , Okada Hideyuki , Kato Ryogo 
Published: December 2024

A perfluorinated sulfonic acid polymer (PFSA) membrane is extensively used in proton exchange membrane（PEM）water electrolyzers for the production of green hydrogen. It is crucial to ensure the membrane’s chemical stability and mechanical durability for long-term performance. PEM is typically assembled with a porous transport layer (PTL), which supports the membrane electrode assembly (MEA), collects current, facilitates water diffusion to catalysts, and must withstand high compressive deformation in a harsh liquid environment over extended periods.
It is known that high pressure applied to polymer materials commonly leads to compressive creep. It has been reported that due to such compressive creep deformation, the catalyst layer applied on the PFSA membrane undergoes significant deformation, resulting in the formation of cracks that degrade the performance1-2). Therefore, it is necessary to investigate the creep response of PFSA membranes on PTLs with various diameters and roughness under different pressure modes in order to understand their mechanical durability for long-term performance.
In this study, a thermal mechanical analyzer (TMA) was utilized in a hydrated environment with water at 80℃ and 6.2 MPa for over 100 hours. Initially, the PEM was placed on the PTL at 23℃ and immersed in the water chamber. The sample was then heated from 23℃ to 80℃, and once the experimental temperature stabilized at 80℃, a load corresponding to 6.2 MPa was continuously applied to the membrane during measurement. As a result, the membrane thickness rapidly decreased from its initial thickness due to the high pressure, and the membrane deformation gradually slowed down. After over 100 hours of measurement, observations using an optical microscope showed that the membrane in contact with the PTL gradually flowed and penetrated into the pore of the PTL. The relationship between the creep behavior and the penetration of the membrane into the PTL pore, considering various PTLs and membranes, will be presented during the poster session.
Reference

T, Schuler. et al., J.
Electrochem. Soc.
166 (10) F555-F565 (2019)

J, Liu. et al., ACS Cent. Sci.
DOI: 10.1021/acscentsci.4c00037
Development of High Proton Conductive Membrane Using the Nano Cellulose Fibers for Polymer Electrolyte Fuel Cells
Authors: Katoh Takashi , Matsuo Yoshimasa , Masuhara Akito 
Published: December 2024

Recently, woody biomass has been used in multiple ways as a carbon-neutral and renewable resource. Among them, cellulose nanofibers (CNFs) are attracting attention as a new nanomaterial derived from cellulose, which is one of the major components of trees. We established a unique CNF production method by introducing phosphate groups to the hydroxyl groups in the wood pulp. The obtained phosphorylated CNFs were completely nanofibrillated (approximately 3 nm in width) with high yield, and their aqueous dispersion was highly transparent, viscous, and stable at pH 3−11. An aqueous dispersion of phosphorylated CNFs can be dehydrated and dried to form transparent CNFs sheet with densely-packed CNFs. This sheet has high transparency, strength, and thermal dimensional stability, and at the same time, it has paper-like flexibility. To promote the practical use of this technology, we have currently been operating a demonstration plant for the production of CNFs aqueous dispersion and CNFs sheet.
By using CNF, which have excellent water retention and film-forming properties, we developed a nanocellulose PEM that is weakly acidic, has low environmental impact, and has high proton conductivity. The PEM using cellulose nanofibers showed a high proton conductivity of >7×10-2Scm-1 under 95% RH at 80 ℃. By combining a PVPA filler in a CNF suspension, it has become possible to easily create a self-supporting membrane using CNF as a binder. This composite membrane showed an especially high proton conductivity of 9×10-2 Scm-1 under 95% RH at 80 ℃. These results suggest that CNF presents a high potential substitute for perfluorosulfonic acid polymers and serves as a pivotal component of environmentally sustainable PEMs.
Effect of Post-Heat Treatment of Catalysts Under Various Gas Conditions on the Microstructure of Catalysts Ink and Electrode for PEMFC
Authors: KIM Sungmin , Kang Yun Sik , Lim Iksung , Lee Eunjik , Woo Seunghee , Park Seok-Hee , Park Gu-Gon , Yim Sung-Dae 
Published: December 2024

Polymer electrolyte membrane fuel cells (PEMFCs) directly convert the chemical energy of fuel into electrical energy, producing electricity through a high-efficiency, ecofriendly energy conversion device. While PEMFCs are commercialized now, enhancing their competitiveness compared to other energy sources is critical and requires an understanding of the microstructure of the membrane-electrode assembly. Typically, fuel cell electrodes are manufactured by coating an electrolyte membrane with catalyst inks composed of electrode catalyst, ionomer, and solvent or additives. To maximize the performance of fuel cells, the proper distribution of catalysts and ionomers within the electrode is essential, and the microstructure within the electrode is determined by the interactions between the carbon support and platinum surface, as well as the dispersion of catalysts and ionomers in the solvent. Thus, the internal microstructure of the catalyst ink, determined by the interactions among its constituents, ultimately defines the final electrode microstructure, affecting the performance and durability of the fuel cell.
This study aims to analyze the effects of post-heat treatment of catalyst in various gas atmospheres, including NH3 gas, on the surface characteristics and to examine the changes in interactions between the catalysts and ionomers within the catalyst ink following surface modification. Additionally, this research seeks to elucidate the correlation between the properties of the catalyst ink and the characteristics of the electrode produced by drying the ink. To this end, the physical properties of the thermally modified catalysts were analyzed, and the resulting catalyst ink was also manufactured and examined. The physical and rheological properties of the catalyst ink were assessed using a dispersing analyzer and rheometer to understand the interactions between the catalysts and ionomers. Furthermore, the coatability of the catalyst ink and the structural characteristics of the electrode were investigated.

Figure 1
Engineering Anode Catalyst Supports for Enhancing Anode Reversal Tolerance in Proton Exchange Membrane Fuel Cells
Authors: Li Zheng , Zhao Tianshou , Zeng Lin 
Published: December 2024

The "hydrogen society" concept has emerged as a response to the increasing demand for carbon-free energy and the aim of achieving "carbon neutrality". Proton exchange membrane fuel cells (PEMFCs) are considered the most promising hydrogen energy utilization units for commercialization, despite facing challenges related to durability and cost. One of the key obstacles is anode reversal, which inevitably occurs during the operation of PEMFC and significantly reduces performance, eventually leading to failure. Therefore, it is essential to investigate the mechanisms that affect anti-reversal performance and find effective strategies to improve reversal tolerance without compromising performance.
Two approaches have been put forward. First, we aim to enhance the reversal tolerance of proton exchange membrane fuel cells (PEMFCs) by using polyaniline (PANI) coated carbon as a catalyst support. The PANI coating acts as a protective layer that isolates the carbon from the corrosive environment, resulting in improved anti-reversal performance. Moreover, the PANI coating helps to distribute the catalyst nanoparticles and ionomer uniformly, leading to enhanced polarization. We have tested various carbon supports to confirm the applicability of this coating strategy and optimized the thickness of the PANI coating to avoid any adverse effects on performance. Additionally, we have developed a high-specific-surface-area conductive oxide Ti4O7 as an anode catalyst support to overcome the negative effects of carbon corrosion. By shortening the electron transfer pathway and increasing metal coverage, we have achieved comparable polarization performance to conventional carbon-supported counterparts. Our Ir@IrOx/Pt/Ti4O7-fabricated RTA has demonstrated approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than the conventional carbon-supported counterpart. These systematic studies aim to promote the development of highly durable and reversal-tolerant anodes, providing a promising outlook for practical, high-performance, low-degradation, and cost-effective RTA fabrication.
Stem-Inspired Self-Contained Support for High-Power Proton-Exchange Membrane Fuel Cells
Authors: Zhang Ao , Wang Ran , Bazaid Mohammed , Tsai Yu-Han Joseph , Hsiao Ting-Jung , Goddard William A , Jang Seung Soon , Huang Yu 
Published: December 2024

Proton-exchange membrane fuel cells (PEMFCs), which utilize hydrogen and air to produce emission-free power, offer a promising avenue toward a cleaner energy future. However, for PEMFCs to become a practical and widely adopted solution, it's imperative to reduce the usage of platinum (Pt) while simultaneously enhancing cell performance significantly. The conventional cathode catalyst layer (CCL) within the membrane electrode assembly (MEA) of PEMFCs consists of the ionomer and carbon-supported Pt-based catalyst. While the ionomer provides the crucial, and currently the only means that facilitates micron-level proton conductivity which is necessary for the oxygen reduction reaction (ORR) throughout the cathode catalyst layer, it also introduces extra local (non-Fickian) resistance to oxygen transport when it covers the Pt surface. This resistance accounts for more than 40% of the total mass transport resistance of oxygen and protons in the cathode, hindering high performance. Furthermore, this local oxygen transport resistance escalates inversely with the decrease in Pt loading within the cathode, exacerbating the barrier of mass transport at ultralow Pt loadings and significantly limiting MEA power output. Additionally, the sulfonic acid group in the ionomer's side chain tends to strongly adsorb onto the Pt surface, thereby poisoning Pt activity and compromising MEA performance. Addressing these challenges is crucial to PEMFCs for widespread adoption as a clean energy solution.
Here, we developed a novel self-contained support structure (SCSS) that can synchronously conduct both electrons and protons for the ORR without ionomers. Thus, we effectively eliminate the detrimental effects of ionomer poisoning and oxygen transport resistance caused by ionomer presence in the CCL. We observed an impressive two-times higher specific activity of the PtNi in SCSS compared with the PtNi in CCL with the ionomer. Remarkably, the non-Fickian oxygen transport resistance measured from MEA fabricated with SCSS is only 5% of the conventional MEA, leading to a notable 36% increase in the peak power and demonstrating the promising future of the SCSS design, especially for MEAs with ultralow Pt loading.
(Invited) Durability Analysis of Meas with Reversal Tolerant Anodes Under Repeated Cell Reversal Conditions
Authors: Ahn Chi-Yeong , Kim Yunho , Park Jung-Hyung , Kim Young-Shik , Shim Hyungwon 
Published: December 2024

As regulations on greenhouse gas emissions are being strengthened, polymer electrolyte fuel cells (PEFCs) are being applied as a power source in a variety of applications. Mobility such as cars, ships, trains, airplanes, etc. have dynamic operating conditions. Because these operating conditions affect the durability of fuel cells, many studies have been reported analyzing durability of the membrane electrode assemblies (MEAs) by applying repeated operating conditions. 'Cell Reversal’, where the fuel cell voltage drops below 0V, is one of these operating conditions. This phenomenon is observed when electric energy is continuously consumed under hydrogen starvation conditions at the anode or when the required electric energy suddenly increases.
In this talk, first, we attempted to find the optimal additive ratio by controlling the additive content of the electrode. Second, the durability of MEAs with three different types of electrocatalysts and additives was analyzed. Lastly, we will discuss strategies to further improve the durability of MEAs with additives in the anode.

Acknowledgements

This research was supported by a grant from Endowment project of “Development of Basic Technologies in Eco-friendly Ship Fuel Reliability and Safety Evaluation” funded by Korea Research Institute of Ships and Ocean Engineering (PES5100), and this research was also supported by a grant from “Development on operation and reliability verification technology of 1MW class eco-friendly ship fuel and power system under ocean environment (RS-2021-KS211507/PMS5950) funded by the Ministry of Oceans and Fisheries of Korea
Nanoscale in-Situ Effects of Humidity on Proton Exchange Membrane Fuel Cell Catalyst Layers Using Scanning Transmission X-Ray Microscopy
Authors: Parmar Harsharaj Birendrasingh , Seip Tess , Wang Jian , Hitchcock Adam , Bazylak Aimy 
Published: December 2024

Polymer electrolyte membrane (PEM) fuel cells produce clean energy using hydrogen and oxygen with water and heat as the only byproducts. However, their widespread adoption is still hindered by high cost and low efficiency. PEM fuel cells have a proton exchange membrane (ionomer) supported by platinum (Pt) catalyst layers to facilitate the hydrogen oxidation (anode) and the oxygen reduction (cathode) reactions. While sufficient membrane hydration is necessary to maintain proton conductivity, excess water in the catalyst layer can severely inhibit electrochemical reactions, limiting efficient fuel cell operation.
To design high performance catalyst layer nanostructures, the formation of liquid water and the ionomer swelling with humidity in PEM fuel cell catalyst layers need to be investigated. In-situ hard X-ray techniques have been used to study the incipience of water; however, the high energy hard X-rays prevent spectroscopy of the low-Z membrane elements like carbon, fluorine, oxygen, and sulfur. Soft X-ray scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy can uniquely perform high resolution (30 nm) imaging of the chemical constituents of catalyst layers with minimal radiation damage. In this work, we report a novel in-situ characterization of ionomer swelling with humidity in fuel cell catalyst layers using STXM and NEXAFS spectroscopy to reveal the nanoscale reactant and proton transport pathways in PEM fuel cell catalyst layers. Pristine catalyst coated membrane samples were cut using an ultramicrotome to obtain 300 nm thick sections and mounted in a custom cell to observe the in-situ effects of humidity. The thickness of liquid water in the membrane and catalyst layer as a function of relative humidity was obtained by performing in-situ imaging at the oxygen K-edge. We observed that at 55% relative humidity (RH), a through-plane water accumulation of 10-20 nm on the silica nanoparticles maintained the membrane proton conductivity and at 90% relative humidity, the hydration of the sulfonic acid sidechains of Nafion promoted nanoscale proton transport in the catalyst layers. Moreover, in-situ characterization of ionomer swelling with humidity was performed for the first time using NEXAFS at the fluorine K-edge. The ionomer volume fraction increased from 28% to 36% from dry (~6% RH) to humidified conditions (~90% RH) and resulted in higher nanoscale oxygen and water diffusion resistance. From these analyses, the effects of hydration on nanoscale mass transport and proton conductivity were quantified to inform the design of next-generation proton exchange membrane fuel cells.

Figure 1
(Invited) How Interfaces Control Lithium (De)insertion Pathway: Comparing Liquid and Solid Electrolytes
Authors: Lim Jongwoo 
Published: December 2024

In the realm of lithium-ion batteries, the process of lithium (de)insertion follows a two-fold pathway, encompassing (1) charge transfer occurring at the electrolyte-electrode interface and (2) solid-state lithium diffusion within electrode. Conventionally, these two transport mechanisms have been regarded as distinct and investigated separately due to their sequential occurrence during battery cycling. However, our recent research demonstrates that the kinetics of charge transfer can exert control over the spatial distribution of lithium on the surface, consequently influencing the entire lithium (de)insertion pathway.
In addition, in the field of all-solid-state batteries (ASSBs), the interface between solid-electrolytes and electrodes further modulates the surface charge transfer kinetics, active surface areas, and local stresses. Chemo-mechanical properties in ASSBs complicate interfacial charge transfer and further affect lithium diffusion within the electrodes. In this talk, I will present how our synchrotron-based operando X-ray diffraction and imaging could help understand such phenomena.
Characterisation by Advanced Experimental Methods of Components in PEM Fuel Cells and PEM Electrolyses
Authors: Martinelli Anna , Schulz Dylan 
Published: December 2024

Hydrogen based technologies, such as PEM fuel cells and PEM electrolyses, are attracting increasing attention and will be central for the transition to a renewable energy system. In order to be integrated part of the electricity grid and hence make an impact on society, however, the efficiency of these devices must increase as well as their durability should be assessed. Efficiency and durability are a complex result of the properties of several components, which include the gas diffusion layer, the catalyst and the proton exchange membrane, the performance of each relating closely to the conditions of operation.
In this oral, I will present our ongoing work in developing advanced experimental methods, heavily based on vibrational spectroscopy, that enable studying the degradation of proton exchange membranes (type of chemical or mechanical damage), the morphological evolution of catalytic particles during fuel cell operation (including morphologies other than spherical) as well as the correlation between PTFE content in the gas diffusion layer and electrochemical performance. The figure below, for instance, shows preliminary results on the local distribution of PTFE in a gas diffusion layer mapped by Raman spectroscopy.

Figure 1
A Lifetime Prediction Model for the Anode Catalyst Layer in PEM Electroyzers
Authors: Van-Brunt Alexander John 
Published: December 2024

Electrolyzer stacks (ELY stacks) are anticipated to form a key component in the hydrogen economy by providing a clean hydrogen source which may be deployed modularly. Currently, proton-exchange-membrane (PEM) electolyzers are a promising candidate to meet this demand on account of their high performance relative other electrolysis methods. Amongst other considerations, economic barriers preventing the uptake of PEM ELY stacks are the durability and cost of the precious catalyst materials, especially iridium-loaded catalysts. Additionally, due to the ever-growing uptake of intermittent power sources, dynamic operation of the ELY stack is an attractive economic option, yet may also accelerate degradation. Taken together, a key question in the design and deployment of ELY stacks is predicting the lifetime of the anode catalyst layer under dynamic power loads.
In this presentation we present a simple model for lifetime prediction of the anode catalyst layer of a PEM electrolyzer with iridium dissolution as the principal degradation mechanism. The model is parameterized from data in the literature and wind and solar profiles are used as validation. Implications in the design of accelerated stress tests are also discussed.