bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indirect and Direct Observation of Ionomer Colloidal Systems with Applications to Fuel-Cell Catalyst Layers
Authors: Hatzell Kelsey B. , Kusoglu Ahmet , Dudenas Peter , Kariuki Nancy , Myers Deborah J , Weber Adam Z 
Published: February 2020

Manufacturing methods for fuel cell catalyst layers are critically important for achieving high material utilization and performance. Typically, electrode systems are cast from an ‘ink’ or ‘colloidal’ state, where the solid material is suspended in a solution containing a solvent and a polymer. For polymer-electrolyte fuel cells, a perfluorinated sulfonic-acid (PFSA) ionomer, typically Nafion, is used in the ink and catalyst layer, where its roles are to act as a binding agent and conduit for proton conduction to the reaction site.1 Recently, it has been suggested that the ionomer film that surrounds the platinum reaction site may contribute to increased resistances that limit performance at low Pt loadings.1,2 Thus, it is of great interest to understand the factors controlling the film formation in catalyst layers to optimize material properties and cell performance. The nature of the dispersion and casting process could have significant influence on the morphology and properties of the dispersion-cast membranes.3-5 To isolate these effects, the morphology of PFSA dispersed in various solvents (glycerol, water/2-propanol, and NMP) was reported previously using small angle neutron scattering (SANS), where catalyst layers from the different solvents exhibit different performance.6 The understanding of local‘ink’ structures as a function of active material (polymer and solid) volume fraction (Φ) and across solvent space and length scales can aid in understanding bulk properties and the impact of ink formulation in cast systems. In this talk, a direct observation of the colloidal suspension of the ionomer in different solvents will be described using confocal laser scanning microscopy (CLSM). CLSM has long been utilized as a tool for characterizing the structure of biphasic colloidal gels. We combine dynamic light scattering, ultra-small angle x-ray scattering, and confocal microscopy to understand PFSA size and structure in dilute (1,3, and 5 wt%) ionomer solutions. The structural formation of nafion membranes are observed in-situ with small angle x-ray scattering. Finally, we contrive a model ‘ink’ composed of attractive and repulsive silica spheres and PFSA suspended in different solvents (water, NMP, and isopropyl-alcohol) and use CLSM to gain a greater understanding about solid|PFSA interactions in model inks.
1. A. Z. Weber and A. Kusoglu, Journal of Materials Chemistry A, 2, 17207 (2014).
2. A. Kongkanand and M. F. Mathias, The Journal of Physical Chemistry Letters, 1127 (2016).
3. T. T. Ngo, T. L. Yu and H.-L. Lin, Journal of Power Sources, 225, 293 (2013).
4. C.-H. Ma, T. L. Yu, H.-L. Lin, Y.-T. Huang, Y.-L. Chen, U. S. Jeng, Y.-H. Lai and Y.-S. Sun, Polymer, 50, 1764 (2009).
5. Y. S. Kim, C. F. Welch, R. P. Hjelm, N. H. Mack, A. Labouriau and E. B. Orler, Macromolecules, 48, 2161 (2015).
6. C. Welch, A. Labouriau, R. Hjelm, B. Orler, C. Johnston and Y. S. Kim, Acs Macro Letters, 1, 1403 (2012).
Hydrogen Fuel Cells for Unmanned Undersea Vehicle Propulsion
Authors: Swider-Lyons Karen , Deitz Daniel 
Published: February 2020

Hydrogen fuel cells materials and systems have attracted billions of dollars of government and commercial research such that they are now reliable and cost effective enough to be commercialized as the power source for automobile propulsion and for materials handling. Also known as polymer electrolyte membrane fuel cells (PEMFCs), hydrogen fuel cells are attractive because they convert high-energy hydrogen fuel and oxygen (typically from air) efficiently to electricity and water through electrochemical processes, and produce relatively little heat and noise. They also respond rapidly to changes in load. The result is that they can have higher specific energy and energy density than battery systems for certain applications. One such application for commercial automotive hydrogen fuel cells is for large unmanned undersea vehicles (UUVs). This paper will describe an Office of Naval Research effort by the U. S. Naval Research Laboratory, Naval Surface Warfare Center Carderock Division, University of Hawaii, and General Motors (GM) to integrate an automotive fuel cell from GM into an unmanned undersea vehicle. The advantages and challenges with taking commercial fuel cell technology and adapting it to undersea use will be discussed.
(Invited) Development of a Hydrogen Energy System as a Grid Frequency Management Tool
Authors: Ewan Mitch , Rocheleau Richard , Swider-Lyons Karen , Devlin Peter , Virji Maheboob B.V. , Randolf Guenter 
Published: February 2020

In Hawaii, very high penetration levels of intermittent renewable energy sources such as wind and solar are causing challenges in regulation of grid frequency, and as the percentage of these intermittent resources increases can result in their curtailment. It has been postulated that, similar to a battery, the optimized use of an electrolyzer as a variable load may help regulate grid frequency and increase the penetration of renewable energy resources on the grid. The use of an electrolyzer in this way could provide an “ancillary service” to the grid that can be assigned a monetary value. This monetary value can be used to offset the cost of hydrogen production. The hydrogen in turn can be used in high value applications such as a transportation fuel. The Hawai‘i Natural Energy Institute (HNEI) is conducting research to assess the technical potential and economic value of using an electrolyzer-based hydrogen production and storage system as a demand response tool for grid management. A 65 kg/day hydrogen energy system (H2ES) consisting of a PEM electrolyzer, 35 bar buffer tank, 450 bar compressor, and associated chiller systems, has been purchased and installed at the Hawaii Natural Energy Laboratory Hawaii Authority (NELHA) to demonstrate long-term durability of the electrolyzer under cyclic operation required for frequency regulation on an island grid system. A secondary objective is to supply hydrogen for three fuel-cell buses to be operated at Hawai‘i Volcanoes National Park (HAVO) and by the County of Hawai‘i Mass Transit Authority. The hydrogen will be transported from the production site by tube trailers to the HAVO dispensing site. A second dispensing site is located at the NELHA production site.
A comprehensive test plan has been developed to characterize the performance and the durability of the electrolyzer under dynamic load conditions and initial testing was conducted at Powertech Labs in Vancouver Canada. A main objective of the test plan is to determine the operating envelope and dynamic limits of the electrolyzer and the overall H2ES. A long-term study shall evaluate the H2ES performance under a load profile developed from a fast acting Battery Energy Storage System (BESS) that is currently in use as a grid management tool on the Big Island grid. These tests shall demonstrate whether the electrolyzer has the capability to effectively mitigate the impacts of intermittent solar and wind power on the grid, while continuously generating 90-80% of its designed hydrogen productioncapacity.
The presentation will describe the H2ES configuration, plans for operation in the field, and results of initial tests to determine the dynamic response of the eletrolyzer and overall system
Cobalt Alloyed Catalyst Combined with Carbide and Carbon As Efficient Oxygen Evolution Reaction Catalysts for Alkaline Water Electrolysis
Authors: Kim MinJoong , Song DongHoon , Oh SeKwon , Cho EunAe 
Published: February 2020

Increasing demand for clean energy have triggered researches on alternative energy sources and devices to reduce use of fossil fuel. Hydrogen has been considered as one of the most promising energy source for future due to its high energy density and no air pollutant emission. Splitting water into hydrogen and oxygen is an environmentally friendly method for producing hydrogen gas. This technology can store excess electric energy in the form of chemical bonds of hydrogen, which can resolve an issue about surplus electric power of present renewable energy systems caused by irregular energy source such as airflow and sunlight.
Water electrolysis reaction is divided into two half reactions; hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). High overpotential of both HER and OER is the most significant problems to hamper reaction rate and overall efficiency of water electrolysis, especially OER has much higher overpotential than HER. Therefore, recently major efforts have been devoted to exploring active catalysts for the OER in water electrolysis cell.
Among many kinds of candidate materials for OER catalyst, cobalt (Co) and various Co based materials, including nanostructured Co3O4, CoSe2, Co based perovskites, CoP, CoB and Co/N-doped carbon, have drawn much attention for use in the alkaline water electrolysis system. These Co based catalysts have high OER activity in alkaline media comparable with precious metal based catalysts, such as IrO2 and RuO2. However, previous studies has focused mainly on the exploring desirable composites for low OER overpotential without careful mechanistic study. OER mechanism on Co based catalysts and descriptors for designing more efficient catalysts have been unclear yet.
Herein, we tried to modify the electronic structure of Co through the strain effect. The strain effect modifies the adsorption energy of gaseous or ionic species for OER on Co surface that can be an effective way to design an active electrocatalyst. For making a strain in the Co lattice, we alloyed Co with other transition metals, such as iron (Fe), manganese (Mn), nickel (Ni), and combined with carbide and carbon through a facile solution based process. Graphitic carbon-nitride (g-C3N4) was used as a carbon source. Synthesized alloyed catalyst exhibited higher activity and durability for OER compared with Co and ruthenium dioxide (RuO2) catalysts in alkaline media (0.1 and 1 M KOH). And, the catalysts with tensile strain have much enhanced OER activity than compressive strained one.
(Invited) The Implications of Cation Clustering in Anion Exchange Membranes on Conductivity and Mechanical Properties
Authors: Herring Andrew M , Coughlin E. Bryan , Liberatorre Mathew W. , Pandey Tara P , Sarode Himanshu N , Liu Ye , Di Noto Vito , Vezzù Keti 
Published: February 2020

The potential of anion exchange membrane (AEM) fuel cells to provide inexpensive compact power from a wider variety of fuels than is possible with a proton exchange membrane (PEM) fuel cell, has continued to drive the research interest in this area. Alkaline catalysis in fuel cells has been demonstrated with non-precious metal catalysts, and with a variety of fuels beyond H2 and methanol. Alkaline fuel cells (AFCs), based on aqueous solutions of KOH, have serious drawbacks associated with system complexity and carbonate formation. Anion exchange membrane (AEMs) fuel cells have a number of advantages over both PEM fuel cells and traditional AFCs; however, although anionic conductivity in AEMs can be comparable to PEMs the chemical stability of membrane attached cations in hydroxide is still not always sufficient for practical applications. Recently, it has been recognized that a number of advanced cations, may give AEMs the needed chemical stability. In some circumstances simple trimethyl benzyl ammonium cations are stable up to 60oC allowing us to being to study hydroxide and water transport in these systems. We use in-plane conductivity and multi-nuclear PFGSE to measure self-diffusion coefficients of the water and where possible, the ion, i.e. F-, carbonate and bicarbonate. Together with temperature and RH dependent SAXS we couple this information with the morphological changes in the materails.
By their nature these organic cations form dipoles, which have a tendency to interact, see Figure below for a trimethylbenzyl cation with bromide for illustrative purposes. For maximum ion transport the cation should be distributed along the polymer chain, however, cation clustering is a common phenomena. It occurs in phase separated diblock polymers when an attempt is made to raise the IEC, no net increase is observed in ionic conductivity above a certain IEC. In many other less structured polymers it occurs in the fully humidified state when the distributed disordered cations order in agglomerates at a disorder/order Tδ. This Tδ is often observed in the operating temperature range expected for a device, in both DMA, DSC, and broadband electric spectroscopy. Interestingly, even though the SAXS clearly shows an agglomeration on the nano-scale, little difference is seen in the bulk conductivity with temperature. However, steric hindernce effects are expected to discourage aggregation, and may allow the cation to tune all properties of the AEM. As these phenomena are so prevalent in AEM materials the implications and science behind them are being investigated by us and will be discussed in this presentation. The implications of more complex cations proposed for stability in AEMs will be described.

Figure 1
NMR As a Tool for the Study and Rational Design of Aems
Authors: Elgammal Ramez Ahmed , Roy Asa Logan , Zawodzinski Thomas Anthony 
Published: February 2020

The use of anion exchange membranes (AEMs) as separators in alkaline polymer electrolyte fuel cells (AFCs) has received considerable interest over the past decade. AFCs offer several advantages over more traditional PEM fuel cells, in particular operating at high pH enables the use of non-precious metal catalysts, drastically reducing the cost of the cells. However, widespread adoption of AEMs has been hampered due to poor stability, in part due to base-induced decomposition of the polymer backbone and cation group as well as conversion to carbonate form, all of which contribute to reduction of ion exchange capacity (IEC), conductivity, and mechanical strength. Furthermore, there is an insufficient understanding on how the polymer nanostructure and microstructure affects stability, transport, and cell performance.
Nuclear magnetic resonance (NMR) spectroscopy is well suited to investigate these issues. We will demonstrate how 1D and 2D NMR spectroscopy may be utilized to characterize the degradation of AEMs using both model cations and ex situ membranes. Measurements of relaxation, e.g. T1, for a series of AEMs will be correlated with ionic conductivity. We also have used pulsed-field gradient NMR experiments to measure water self-diffusion to assist in deconvoluting how tortuosity, connectivity, and the mobility of water in hydrophobic and hydrophilic domains are governed by the nature of the cation and polymer backbone. The ultimate goal of this work is to develop a structure-activity relationship to assist in the design of novel materials with desirable properties.
Electrochemical Behaviors of Directly Deposited Pt on Specific CNT As an Electrocatalyst for ORR
Authors: Yoshitake Masaru , Tanaka Yumi 
Published: February 2020

Pt has been considered the best element for ORR in acidic condition in the point of activity, stability and power density. Pt catalysts for ORR have been often prepared using Pt compounds as starting material in aqueous solutions. The melting temperature, Tamman temperature and Huettig temperature of Pt are much higher than those of Pt compounds such as chlorides and oxides unlike Ni, Cu (1). It might be effective to deposit Pt metal directly on support to get better dispersed catalyst particles compared with the conventional methods. A liquid phase process and gas phase processes were found to be able to afford higher activity than conventional methods for various supporting materials. It was found that specific CV curves and extremely high mass activity in the case of CNT with low D/G as a catalyst support. as shown in Fig.1. The measurement condition was executed under the condition deciced based on the discussion with Y. Takasu and W. Sugimoto (2). It is very interesting that high ORR mass activity and the strong shift of HUPD to lower potential can be observed at the same time(3,4) in the electronic structure of Pt surface. We have started to discuss this behavior related with the surfacee electronic structure of Pt, the bonding between Pt and C, stability of the catalyst.

References

1. J.A. Moulijn, B. Silberova, M. Makkee and F. Kapteijn, "Catalyst Deactivation and Process Design", 10th Internatinal Symposium on Catalyst Deactivation, February 5-8, 200 in Berlin/Germany.

2. Y. Takasu, W. Sugimoto, M. Yoshitake, "Examination of the Evaluation Method with the Common Catalysts for PEFC Cathode-3(Summary)", State-of-the-art Fuel Cells and Hydrogen Technology in Japan, - Collected from the 20th FCDIC Fuel Cell Symposium and the 1st FCV Forum, Fuel Cell Development Information Center, (2014).
3. M. Yoshitake et al, "Electrode material and method for producing same", WO2012053561 A1.

4. M. Yoshitake, "Development of PEFC at Asahi Glass Co., Ltd.", IUMRS-ICEM2010, Symposium H. Materials and Devices for FUel Cells, August 26,2010, Korea.

Figure 1
Electrospinning Strategies for PFSA/PVDF Nanofiber Composite Membrane Fabrication
Authors: Pintauro Peter N. , Park Jun-Woo , Rahmani Shahrzad , Powers Devon , Wycisk Ryszard , Nguyen Trung Van , Arefazarand Ahmad 
Published: February 2020

Historically, the general strategy for developing new ion-exchange membranes focused almost exclusively on the synthesis of new polymers with a high IEC, where the ion-exchange groups are strongly dissociable. Unfortunately, the use of polymer chemistry alone has not been successful in achieving the performance goals of next-generation proton conducting membranes for fuel cells and redox flow batteries. For example, simply increasing the ion-exchange capacity of a polymer to improve conductivity has lead to polymers that are brittle when dry and swell excessively in water, with a loss in mechanical strength and counterion/coion selectivity. To overcome the problems with highly charged single polymer membrane systems, researchers have: (i) investigated block copolymers which self- assemble into separate phases, where one block provides selective transport pathways and the second block imparts mechanical strength, (ii) combined the desirable properties of two different polymers in a single membrane through blending, (iii) impregnated a functional polymer into a microporous inert support, where the support provides the requisite mechanical properties that the functional polymer lacks, and (iv) crosslinked the ionomer.
The present paper will focus on blended ion exchange membranes, composed of perfluorosulfonic acid (PFSA) and polyvinylidene fluoride (PVDF), where nanofiber electrospinning is used to control/alter the nano/micro distribution of PFSA and PVDF. Three membrane fabrication strategies will be presented, using 1100 and 825 EW PFSA and Kynar PVDF: (1) dual fiber electrospinning, where the final membrane morphology is an ionomer matrix with an embedded network of uncharged PVDF reinforcing nanofibers, (2) electrospinning of submicron fibers composed of a PFSA/PVDF polymer blend, followed by fiber mat processing to create a dense and defect-free film, where the morphology is that of randomly oriented bundles of PFSA and PVDF nanofibrils, and (3) core-shell single fiber electrospinning, where the core is PVDF and the shell is a mixture of PFSA and PVDF, followed by compaction and densification to create a dense membrane, where the final membrane structure is similar to that of (1). The methods for fiber electrospinning and follow-on mat processing will be described. Physical property data will be presented for the different fabrication schemes and for different PFSA/PVDF membrane compositions. The use of selected membranes in hydrogen/air and DMFC fuel cells and H2/Br2 redox flow cells will be discussed.
Multi-Layer Thin Film Coatings on Bipolar Metal Plates for PEMFC
Authors: Gath Kerrie K. , Ricketts Mark , Yang Jun , Xu Chunchuan , Hirano Shinichi 
Published: February 2020

The proton exchange membrane fuel cell (PEMFC) offers the potential for an efficient, and reliable power source for vehicles. The bipolar plates are a key component in the stack providing mechanical support, supplying reactant gases to both anode and cathode, removing the reaction products, and providing electrical and thermal conductivity. [1] Bipolar plate materials are broadly divided into metallic and carbon-based materials. Carbon-based plate materials do well mechanically; still fabrication is difficult and costly. As a result, metallic bipolar plates are becoming increasingly popular.[2] Metal bipolar plates have all the necessary properties (including high thermal and electrical conductivity, low gas permeability, high manufacturability, and relatively low cost materials); however, chemical instability due to the highly corrosive environment of the PEMFC leads to the formation of a passive surface oxide layer.
Altering the surface by coating with a corrosion resistant material can be cost prohibitive when considering the amount of coating necessary to overcome the harsh conditions in a PEMFC, fabrication of the coating, and the number of plates in a stack. Less costly metals for coating, such as titanium, typically form an oxidative layer while non-corrosive metals can form pits where the underlying metal becomes exposed. Our multilayer technique combines both metal types for a corrosion resistant economical solution. [3] This design prevents oxide formation from percolating throughout the layered structure via thin films of non-corrosive layers alternated with thicker Ti layers. The specialized structure of multilayers of thin films (Au/Ti) allows the noncorrosive layer, the most costly, to be <1 nm while maintaining the viability and conductivity of the coating and the metal bipolar plate.
[1] H. Tsuchiya and O. Kobayashi, “Mass production cost of PEM fuel cell by learning curve,” International Journal of Hydrogen Energy, 29 (2004) 985–990
[2] K. RoBerg and V. Trapp, “Graphite-based bipolar plates,” in Handbook of Fuel Cells Fundamentals, Technology and Applications, W. Vielstich, A. Lamm, and H. A. Gasteiger, Eds., JohnWiley & Sons (2003) 308–314
[3] S Wang, J. Peng, W. Lui, and J. Zhang, Performance of the Gold-plated Titanium Bipolar Plates for the Light Weight PEM fuel cells,” Journal of Power Sources 162 (2006) 486–491 SHAPE \* MERGEFORMAT

Figure 1. Multilayer design model.

Figure 1