bluuebunny/crossref_metadata_2025 huggingface dataset:
Membraneless Electrolyzers for Low-Cost Hydrogen Production
Authors: Pang Xueqi , Das Saurish , Davis Jonathan T , Esposito Daniel V.
Published: May 2020

Electrolyzers are expected to be core technologies in a renewable energy future because of their ability to use electricity from solar photovoltaics or wind to convert water to hydrogen (H2) by water electrolysis. H2 is an energy-dense fuel, which can be stored for long periods of time. The most prevalent electrolyzers in the market are alkaline electrolyzers and polymer electrolyte membrane (PEM) electrolyzers, which contain membranes/diaphragms that facilitate ion transport between the anode and cathode while physically separating product species evolved from the electrodes. However, these systems are costly and can be prone to degradation. To compete with H2 produced from steam methane reforming, it is essential to reduce system capital costs. As an alternative to these conventional electrolyzers, membraneless electrolyzer architectures have the potential to produce low-cost H2 due to their simplified design that omits a membrane altogether. However, the dynamics of multiphase flow between two electrodes can have a strong impact on product purity due to product cross-over and must be quantified to improve these technologies. In this study, a high-speed camera is used as an in-situ analytical tool to investigate the bubble dynamics within parallel plate membraneless electrolyzers. By detecting bubbles downstream of the electrodes, bubble plume width can be determined before bubbles are separated into different effluent channels. The bubble plume width determined by the high-speed video (HSV) analysis is in good agreement with the gas product cross-over measured by gas chromatograph (GC). This study demonstrates the ability to use HSV analysis to predict cross-over and optimize the operating conditions, as well as guiding the selection of the electrode gap of parallel plate membraneless electrolyzers.
Electron Microscopy Study of Platinum Group Metal-Free Catalysts Synthesized By High-Throughput Approaches
Authors: Cullen David A. , Zachman Michael J. , Ferrandon Magali , Park Jaehyung , Myers Deborah J.
Published: May 2020

Platinum group metal-free (PGM-free) catalysts are being explored for the oxygen reduction reaction in proton exchange membrane fuel cells. Since both their mass activity and durability are lagging their more developed Pt-based counterparts, accelerated catalyst discovery is this area is sorely needed. High-throughput approaches to catalyst synthesis and testing are an ideal approach to exploring this broad design space which includes precursor type, transition metal loading, and pyrolysis temperature. A range of such materials were synthesized and tested in Argonne National Laboratory’s High Throughput Research Laboratory and characterized by a variety of advanced analytical techniques, including scanning transmission electron microscopy (STEM). Low-voltage, aberration-corrected STEM was coupled with spectroscopic techniques to quantify atomic scale differences in the morphology of each catalyst. These highly localized measurements were coupled with X-ray techniques, including X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, to achieve a more complete view of the structural properties which impact mass activity and durability and the synthesis conditions which achieve such structures. These results, along with the application of new STEM imaging modalities and combinatorial techniques to accelerate throughput, will be presented. This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office under the Electrocatalysis Consortium (ElectroCat). Microscopy performed as part of a user project at ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility.
A Highly Active Iron-Based ORR Catalyst Via Chemical Vapor Deposition
Authors: Jiao Li , Li Jingkun , Sougrati Moulay-Tahar , Yang Fan , Zhong Sichen , Xu Hui , Mukerjee Sanjeev , Myers Deborah J. , Jaouen Frederic , Jia Qingying
Published: May 2020

Remarkable advancement of platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) makes them a promising alternative to Pt-based catalysts in polymer electrolyte membrane fuel cells (PEMFCs). Commercialization of the Fe-N-C catalysts as the current leading PGM-free ORR catalysts has been hindered by its insufficient activity and durability. Herein, a Fe-N-C catalyst was synthesized via chemical vapor deposition of the gas phase anhydrous FeCl3 onto a metal organic framework (MOF)-derived N-doped carbon (N-C) substrate at 750 ℃. It exhibits excellent ORR activity, with a current density of 33 mA·cm-2 at 0.90 ViR-free (IR-corrected) and 44 mA·cm-2 at 0.89 ViR-free in a H2-O2 PEMFC at 1.0 bar oxygen partial pressure and at a cell temperature of 80°C. The exceptional activity is attributed to the high density of Fe-N4 sites. Combined characterizations show that the Fe-N4 sites are exclusively located on the surface of the catalyst and accessible by gas phase oxygen and that the Fe content is 1.8 wt%.

Acknowledgements

This work was supported by the US Department of Energy under award number DE-EE0008416 and DE-EE0008075. The authors acknowledge the support from the DOE Energy Efficiency and Renewable Energy Fuel Cell Technologies Office (DOE-EERE-FCTO) ElectroCat consortium. This research used beamline 6-BM, 7-BM and 8-ID (ISS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Argonne is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357 by UChicago Argonne, LLC.
One-Pot Synthesis of Nitrogen-Doped Carbon Supported Mn-Co Nanoparticles for Hydrazine Oxidation
Authors: Balčiūnaitė Aldona , Budrytė Eivilė , Vaičiūnienė Jūratė , Niaura Gediminas , Kruusenberg Ivar , Kaare Kätlin , Volperts Aleksandrs , Dobele Galina , Zurins Aivars , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus
Published: May 2020

The nitrogen-doped carbon (N-doped C), that has a graphene-like structure, has been chosen as a support for the deposition of Mn-Co nanoparticles (Mn-CoNPs) using a rapid microwave heating method with the aim to use them as the anode material for direct hydrazine fuel cells (DHFCs). For comparison, the pure CoNPs/N-doped C and MnNPs/N-doped C catalysts have been synthesized under similar conditions. The structure, morphology and composition of the synthesized catalysts have been characterized using Transmission Electron Microscopy (TEM), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The electrocatalytic activity of the prepared Mn-CoNPs/N-doped C, CoNPs/N-doped C and MnNPs/N-doped C catalysts for hydrazine oxidation has been evaluated using cyclic voltammetry and chrono-techniques. Cyclic voltammograms on the prepared catalysts have been recorded in a 0.05 M N2H4 + 1 M NaOH solution at a potential scan rate of 10 mV s–1.

It has been determined that the Mn-CoNPs/N-doped C, CoNPs/N-doped C and MnNPs/N-doped C catalysts show an enhanced electrocatalytic activity towards the oxidation of hydrazine in an alkaline medium. Moreover, the oxidation process of hydrazine on the Mn-CoNPs/N-doped C, CoNPs/N-doped C and MnNPs/N-doped C catalysts is controlled by the diffusion processes. The data on the oxidation of hydrazine on the N-doped C supported Mn-CoNPs, CoNPs and MnNPs under various conditions are compared and discussed.
Investigation of Ionic Liquid/Membrane Matrix for the Mid Temperature PEM Fuel Cell
Authors: Hou Hui , Giffin Jürgen , Korte Carsten
Published: May 2020

Operating polymer electrolyte fuel cells (PEFC) >100 °C allows a significant simplification of the necessary peripheral devices. It allows operation without feed gas humidification—respectively no water recyclation—and a more efficient cooling system. For operation temperatures <80 °C, PEFCs with NAFION® membranes show excellent electrochemical performance. However, at higher temperatures sulfonated fluoropolymer membranes suffers from the drying effects at atmospheric operation which leads to a dramatic decrease of the proton conductivity. When using phosphoric acid (H3PO4) doped polybenzimidazole membranes (PBI), a PEFCs can be operated in the temperature range of 160–180 °C (HT-PEFC). Nevertheless, due to poisoning effects by H3PO4 and its anionic species on the redox catalyst platinum and a low solubility of oxygen in H3PO4, the ORR kinetics is rather sluggish and leads to an insufficient power density. Moreover, at temperatures <150 °C the proton conductivity is not sufficient.

Thus, there is need for new proton conducting membrane materials for operation temperatures of 100–120 °C, whose conductivity is not related to a high degree of water swelling. Proton conducting ionic liquids (PILs) exhibit a high proton conductivity, low volatility and high thermal stability, as well as a high electrochemical stability over a wide temperature range [1-3]. Thus, PILs are the promising candidates as non-aqueous proton conductors.

This experimental study is focused on high Brønsted-acidic sulfoalkylammonium type PILs as 2-sulfoethylmethylammonium triflate [MSEA][TfO], 2-sulfoethylmethylammonium hydrogen sulfate [MSEA][HSA], 3-sulfopropyldiethylammonium triflate [DESPA][TfO] and 3-sulfopropyldiethylammonium hydrogen sulfate [DESPA][HSA]. The physico-chemical properties of the neat PILs, i.e. ORR kinetic current density, oxygen solubility, oxygen diffusivity, electric conductivity and thermal stability, are measured at temperatures relevant for fuel cell operation. Commercial polyetheretherketone (PEEK) and PBI are chosen as host membrane materials to immobilize the PILs in a polymer matrix. The (total) electric conductivity and the thermal stability of the PIL-polymer systems are also evaluated.

The influences of the cations or anions on the PILs and the different immobilization methods of PILs in membrane are investigated. The results show that with different PIL/membrane combinations, significant differences in thermal stability, mechanical stability and electric conductivity are present.

Literature:

[1] Yasuda, T. and M. Watanabe, Protic ionic liquids: fuel cell applications. MRS Bull., 2013. 38(7): p.560-566.

[2] Noda, A., K. Hayamizu, and M. Watanabe, J. Phys. Chem. B, 2001 105(20): p. 4603-4610.

[3] Huang, X.-J., et al., J. Phys. Chem. B, 2009. 113(26): p. 8953-8959.
Introducing an Electrochemically Driven Proton Concentration Process for CO2 Capture
Authors: Rahimi Mohammad , Catalini Giulia , Hatton T. Alan
Published: May 2020

An electrochemically driven proton concentration process was developed for the capture of carbon dioxide (CO2) that was based on modulation of the proton concentration in an electrochemical cell by a proton intercalating MnO2 electrode. The pH sensitivity of CO2 hydration was leveraged such that CO2 was absorbed as bicarbonate and carbonate ions at high pH values and desorbed as gas at low pH values. A comprehensive thermodynamic model developed to determine the speciation, electrochemical performance, and energetics required to desorb CO2 captured from a flue gas was validated by chemical and electrochemical measurements, with very good agreement between simulated and experimental results. The electrochemical work requirement for the proposed proton concentration process to desorb CO2 captured from a flue gas stream was estimated to be 33.2 kJe/molCO2, suggesting that this process is competitive with other electrochemical-based approaches (with energetics ranging from 31.3 to 49 kJe/molCO2). The MnO2 electrode was successfully synthesized using a coprecipitation method followed by casting on either carbon cloth or carbon felt substrate. The fabricated electrodes were characterized using X-ray photoelectron spectroscopy to assess their chemical state, and the formation of MnO2 was confirmed. The capacitance behavior of the electrodes, which is proportional to their electrochemical performance, was evaluated using cyclic voltammetry (CV). The fabricated electrodes were also tested in a symmetrical electrochemical cell with a constant potential applied across the cell. The generated current was effectively translated into proton intercalation/deintercalation reactions through reversible cycles, resulting in modulated proton concentrations in the anode and cathode chambers. The demonstrated model and experimental data suggest that this proton concentration process could be an attractive electrochemical-based route for CO2 capture.
Imaging-Based Analysis for Porous Nickel Materials for Alkaline Water Electrolysis
Authors: Arlt Tobias , Evangelisti Camilla , Markötter Henning , Liebert Michael , Paulisch Melanie , Kardjilov Nikolay , Röntzsch Lars , Rauscher Thomas , Mohseninia Arezou , Boye Jan-Peter , Bergbreiter Christian , Kaczerowski Jürgen , Damm-Ruttensperger Marc , Herrera Raoult , Bächler Heike , Bernäcker Christian Immanuel , Jörissen Ludwig , Manke Ingo , Banhart John
Published: May 2020

Electrolyzer cells are a way of converting and storing excess energy and releasing it again if needed. Beside Li-ion-based batteries, this technique would enable to overcome the intermittent day-dependent availability of electricity (like solar or wind power). The power density and the amount of raw materials needed for the assembly of such cells can be improved through optimized manufacturing processes, especially the sintering process of the electrodes. The sintering process is crucial for the overall performance of an electrolyzer cell. The electrical conductivity as well as the media distribution inside the pores during cell operation needs to be tuned. Hereby, nickel particles are sintered on a nickel substrate. Different substances such as binder and surfactant, are added to the Ni(OH)2 before the sintering process is started. Ni(OH)2 will be reduced to Ni, resulting in an additional Ni coating on the Ni substrate. Material densification, decrease of the porosity and active surface are the most relevant factors during this process. To meet all the requirements a well-balanced sintering process in mandatory. A sufficient electrical conductivity requires well detached particles, while an optimal media transport requires more and large pores. Both can be met by using nickel particles with a defined size distribution of the particle diameters, and a balanced sintering process which significantly affects the conductivity and pores sizes. Moreover, remaining oxidized Ni, which is not an electrochemically active material, decreases the active surface of the sintered material.

This study focuses on the two-phase flow system through newly developed porous nickel materials. Therefore, imaging techniques are combined with electronic measurements and simulations. To characterize these materials results were taken from focused Ion beam (FIB), synchrotron tomography and neutron radiography. Typical structures are coated meshes, foams or expanded metals. The structure of nickel particles was analyzed in 3D using machine learning algorithms for image segmentation. In-operando measurements were performed at the neutron source BER II at Helmholtz-Zentrum Berlin, Germany. Different electric loads and materials were tested in order to obtain additional information to the electronical measurements in terms of media distributions, see figure 1.

The authors gratefully thank the German Federal Ministry for Economic Affairs and Energy (BMWi, Project AEL3D, grant number 03ET6063B) for financial support.

Figure 1
Novel Dendritic Structure for Both Durable and High Performance of PEMFC Using Electrospray Deposition
Authors: Choi Jiwoo , Yeon Je Hyeon , Choi Mansoo
Published: May 2020

The degradation of the proton exchange membrane (PEM) induced by various physical and chemical causes is one of the critical obstacles for the commercialization of proton exchange membrane fuel cells (PEMFCs). Among them, the free radical attack is the main reason for conductivity decrease, membrane thinning and pinholes. Thus, it is crucial to develop a durable electrolyte membrane that can resist free radical attacks while retaining high performance. In this work, we introduce a novel multifunctional dendritic structure composed of a perfluorinated sulfonic acid (PFSA) ionomer and CeO2 nanoparticles using a simple electrospray deposition (ESD) method. The dendritic structure on the cathode side of the membrane enhanced the power performance of membrane electrode assembly (MEA) about 15% owing to the effective utilization of the active sites and enhanced mass transport by voids between the electrode and gas diffusion layer. Moreover, the CeO2 nanoparticle incorporated structures effectively protected PEM from the free radical attacks. The chemical durability of MEA was investigated using Fenton’s test and OCV hold test and the electro-sprayed membrane showed a lower OCV drop rate (0.5mV/h), compared to that of the reference (1.2mV/h).
Meso-Structured Polymer Electrolyte Fuel Cell Electrode
Authors: Komini Babu Siddharth , Wang Xiaojing , Pant Lalit M. , Mukundan Rangachary , Weber Adam Z. , Borup Rod L. , Spendelow Jacob S
Published: May 2020

Increasing the utilization of Pt and Pt alloy catalysts in polymer electrolyte fuel cell cathodes is critical to improving the high power density operation, particularly at low Pt loadings. State of the art electrodes are fabricated in an ink deposition process that leads to uncontrolled electrode architecture with random aggregates of functional domains (catalyst, ionomer, and pore volume) (1). The randomness in the domains induces high tortuosity transport pathways for ions and fluids, which cause severe transport resistance during high current density operation. Thin ionomer films cause additional transport resistance and poisoning of the Pt catalyst, which becomes more significant at low Pt loadings. Reducing the amount of ionomer in the catalyst domain without affecting the ionic transport resistance is key to improving the utilization of the Pt and reducing the transport resistance at low Pt loading.

Rational design of the electrode structure with controlled low tortuous ionic transport pathways could improve performance. The introduction of the ionomer pathways could also enable reduction of the ionomer volume in the catalyst domain, reducing the transport resistance. Middelmen et al. proposed electrode structures consisting of aligned components in a low tortuosity configuration to improve performance (2). In this work, we present an alternative electrode structure based on a vertically aligned array of Nafion pillars in the cathode catalyst layer, as shown in Figure 1a. Figure 1b shows the SEM image of the Nafion pillars. Pt supported on carbon catalyst was deposited on the Nafion pillars to fabricate a meso-structured electrode. Nafion pillars provide high conductive and low tortuous pathways for protons, reducing the effective transport distance, and enabling reduction of the ionomer binder in the catalyst domain.

Acknowledgments

This research is supported by DOE Fuel Cell Technologies Office, through the Fuel Cell Performance and Durability (FC-PAD) Consortium; Fuel Cells program manager: Dimitrios Papageorgopoulos.

References

1. S. Litster and G. McLean, Journal of Power Sources, 130, 61 (2004).

2. E. Middelman, Improved PEM fuel cell electrodes by controlled self-assembly, in, p. 9 (2002).

Figure 1
Synthesis and Characterisation of CsH2PO4(CDP)/NaH2PO4(SDP)/ZrO2 Composites Electrolyte for Fuel Cell
Authors: Veer Dharm , Kumar Pawan
Published: May 2020

Solid acid composite CsH2PO4(CDP)/NaH2PO4(SDP)/ZrO2 were synthesized and characterised with different weight ratio of CDP, SDP and ZrO2. The characterisations of the Solid acid composite were observed the structural, thermal stability and conductivity in terms of X-ray diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and conductivity measurements. The amount of CDP, SDP and ZrO2 pressure used for pallet production and operating temperature. The composites powders were to form of pellets of 1 mm thickness for conductivity measurement. SDP in the composites has a large effect of the conductivity measurement. The supertonic transition was identified at temperature 2350c to 2700c of CDP/SDP/ZrO2 composites under atmospheric pressure. Thermal stability of the solid acid composites such as temperature of dehydration, melting and decomposition were investigated in the temperature range 2300c to 2800c under environments atmospheric humidification.
Methods of Hydroxide-Ion Form Anion Exchange Membrane Characterization
Authors: Meek Kelly M , Antunes Christopher M , Pivovar Bryan S.
Published: May 2020

Alkaline fuel cells (AFCs) are of high interest because they utilize lower cost catalyst and separator materials relative to polymer electrolyte membrane fuel cells. AFCs require anion exchange membranes (AEMs) that have high alkaline durability and high hydroxide ion conductivity. Herein, numerous AEMs from top research groups in the field are evaluated and compared as hydroxide conducting solid state electrolytes. While the hydroxide-anion form of AEMs is the most relevant anion form for alkaline fuel cell and electrolysis applications, it remains difficult to evaluate hydroxide form membranes as they quickly convert to carbonate- and bicarbonate-anion forms upon exposure to air. NREL has developed protocols to allow for high throughput, parallel characterization of AEM materials in hydroxide-anion form. This work assesses six optimized membranes with varied backbone chemical structures: perfluoro (PF), poly(aryl ether sulfone) (PAES), polyethylene (PE), polyfluorene (PFN), polystyrene (PS), polyphenylene (PPN). Methods are established for evaluating true hydroxide-ion properties of these AEMs at varying temperature and relative humidity, including conductivity, durability, and water uptake. Standardized comparisons of the top performing hydroxide conducting AEMs of different backbone types provides valuable insight into optimal chemistries for achieving high conductivity and durability.
Characterization of Ionomer Membranes with Confocal Raman Microscopy
Authors: Böhm Thomas , Moroni Riko , Mu'min Muhammad Solihul , Breitwieser Matthias , Vierrath Severin , Thiele Simon
Published: May 2020

Ionomer membranes are crucial components of electrochemical energy systems such as fuel cells, electrolyzers, or redox-flow batteries. They need to meet demanding requirements for high-performance and long-term stable devices, and a targeted optimization of the membranes requires exact knowledge of parameters such as membrane thickness, ion exchange capacity, or water uptake. We employ confocal Raman microscopy as a tool for in-depth characterization of membranes that are used in proton exchange membrane fuel cells and water electrolyzers. Raman spectroscopy as a vibrational spectroscopy technique is well suited to characterize ionomer membranes, and the combination of Raman spectroscopy with a confocal microscope additionally adds spatial resolution to this chemical analysis. Confocal Raman microscopy is a valuable tool to complement classical characterization of ionomer membranes that provides a plethora of chemical information about the investigated specimen on a single-digit micron scale.

We present our latest results on application-relevant ionomer degradation and water management in membranes determined by confocal Raman microscopy. We found that a Nafion NR-211 membrane that was aged in an accelerated stress test in a fuel cell suffered from severe thinning and an anisotropic increase in its equivalent weight between the electrodes.1 Both are signs of chemical-mechanical degradation and were quantified with high spatial resolution using confocal Raman microscopy (Fig. 1A). Further, we used confocal Raman microscopy to characterize ionomer composite membranes. Composite membranes are a promising approach to optimize membrane properties by e.g. integrating mechanically stabilizing porous networks. We quantified the equivalent weight along the depth profile of a Nafion XL membrane, and also analyzed the influence of the reinforcement layer on water distribution within the hydrated membrane (Fig. 1B).2

Figure 1: Results of ionomer membrane characterization by Raman microscopy. A) Quantification of degradation of Nafion NR-211 in a fuel cell (open circuit voltage (OCV) hold as stress test). B) Through-plane Raman image of water distribution in a Nafion XL membrane.

1. T. Böhm, R. Moroni, M. Breitwieser, S. Thiele and S. Vierrath, J. Electrochem. Soc.,
166(7), F3044-F3051 (2019).

2. M. S. Mu’min, T. Böhm, R. Moroni, R. Zengerle, S. Thiele, S. Vierrath and M. Breitwieser, J. Memb. Sci.,
585, 126–135 (2019).

Figure 1
Photo-Enhanced Ionic Conductivity in Solid-State Oxygen Electrochemical Systems
Authors: Defferriere Thomas , Klotz Dino , Gonzalez-Rosillo Juan Carlos , Rupp Jennifer L.M. , Tuller Harry L.
Published: May 2020

Oxide based Ionic and mixed Ionic – Electronic conductors play strategic roles in applications ranging from energy conversion and storage to thin-film nanoionic devices such as fuel cells, batteries, permeation membranes and nano-electronic memory and sensing devices. Most cost effective production methods for fabricating both bulk and thin films samples often result in the formation of polycrystalline microstructures. Grain boundaries possess significantly different properties to the bulk and often block ion migration, a ubiquitous problem to overcome for a variety of electrochemical energy storage and conversion devices particularly important for low temperature applications. Space-charge potential barriers, featuring depletion zones and band bending, forming at the interface between adjacent grains have been used to explain their blocking nature in polycrystalline semiconductors. In solar cells and in photoelectrochemistry, above bandgap light is well known to contribute to reduced band bending at interfaces by providing additional charge carriers to screen potential barriers. Here, we show that the same principle can be applied as well to ionic conductors and that we can decrease the grain boundary impedance contribution in such systems. We illustrate photoenhanced ionic conduction in 3% Gd-doped ceria upon illumination of a thin film by UV light, whose photon energy is slightly above ceria’s bandgap. We further demonstrate that this effect is not caused by heat or electronic conductivity. Our considerations are based on electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS) measurements, performed on polycrystalline and epitaxial samples, and backed by theoretical considerations of grain boundary potential height and space charge regions.

Figure 1
Sterically Protected N-Heterocyclic Polymers: Unlocking the Potential of Alkaline Anion Exchange Membrane-Based Electrochemical Devices
Authors: Peckham Timothy James , Gholamkhass Bobak , Britton Benjamin , Zhang Ben , Holdcroft Steven , Fortin Patrick
Published: May 2020

There has been considerable interest in alkaline anion exchange membranes (AAEMs) for use in electrochemical applications such as water electrolyzers, reverse electrodialysis and fuel cells.1 However, development of AAEMs has long been hindered by the instability of commonly-used cationic groups (e.g., ammonium, phosphonium) under conditions of high pH and elevated temperature.

At Ionomr Innovations Inc, we have been developing AemionTM, derived from sterically protected, N-heterocyclic-based AEMs, which exhibits remarkably high stability under a variety of different conditions (e.g., pH, temperature). This includes results from both the ex-situ studies commonly found in literature as well as in-situ tests using electrochemical devices (e.g., AAEMFC, alkali water electrolysis) for which no equivalent durability has been found with other commercially available membranes. This presentation will cover some of work in both the ex-situ and in-situ characterization of these materials and progress in scaling them up to production levels.

1. J. R. Varcoe, R. C. T. Slade Fuel Cells 2005, 5, 187-200.
Elucidating Structure-Property Relationships in Highly Permeable Perfluorinated Sulfonic Acid Ionomers
Authors: Katzenberg Adlai , Chowdhury Anamika , Fang Minfeng , Weber Adam Z. , Okamoto Yoshiyuki , Kusoglu Ahmet , Modestino Miguel Antonio
Published: May 2020

Commercially available perfluorinated sulfonic acid ionomers (PFSAs), utilized as polymer electrolytes in membrane electrode assemblies (MEAs), have driven rapid improvements in fuel cell performance. These materials have a polytetrafluoroethylene (PTFE) backbone and semicrystalline matrix which imparts mechanical integrity and low gas permeability, making them attractive membrane materials. However, their low gas permeability introduces significant mass-transport limitations in catalyst layers, especially severe in oxygen reduction at the cathode. In this study, we present the synthesis of an amorphous PFSA incorporating perfluoro(2-methylene 4-methyl-1,3-dioxolane) (PFMMD) in the backbone. This impacted the material nanostructure at multiple length scales, simultaneously increasing gas permeability (>3x oxygen permeability of Nafion) via reduced crystallinity and increased fractional free volume while reducing proton conductivity via changes in matrix mechanical properties which inhibited phase separation of ionomer domains. When integrated in a fuel cell MEA, this trade-off yielded significant improvements; specifically, current density per cm2 platinum increased up to 22% upon substituting the PFMMD based ionomer for Nafion in the cathode binder. In this presentation, I will discuss the facile synthesis of PFMMD based ionomers with tunable PFSA content. Furthermore, I will discuss structure-property relationships resolved from transport measurements and morphological characterization. Finally, I will discuss the implementation of these materials in fuel cells and the potential for meaningful performance improvements. These results demonstrate the value of rational ionomer design toward better performing electrochemical devices.
Dimensionally Stable Anodes Using Titanium Substrates with Nanostructured Surface
Authors: Park Su-Ryeon , Lee Ji-Hwan , Kim Tae-Hoon , Cho Sung-Keun , Chang In-Soung , Park Jin-Soo
Published: May 2020

Over hundread years, so many oxidation technologies have been developed in environmental engineering fields. Mostly, chemical and biological oxidation processes have been enough to treat organic and/or inorganic pollutants to meet the legal emission targets. However, recent wastewater including non-degradable organic compounds demands the development of advanced oxidation technology since non-degradable organic compounds are hardly decomposed by chemical and/or biological treatment technology. Particularly, discharge of toxic or highly concentrated industrial wastewater has been significantly increased due to rapid industrial development to be a serious water pollution. To overcome this problem, various water treatment technologies such as chemical oxidation, precipitation, adsorption, capacitive deionization, electrochemical oxidation and so on have been recently developed and introduced to industry. Among them, electrochemical oxidation of the compounds at anode is environmentally friendly, easily operated and maintained compared to conventional treatment processes. Nonetheless, cost reduction and enhancement of performance/durability of anodic electrodes are highly necessary for commercialization. In this study, TiO2/IrO2/RuO2 electrodes that IrO2 and RuO2 coated on anodized Ti substrate were prepared and investigated in terms of various electrochemical properties.

Acknowledgement

This research was financially supported by the Ministry of Small and Medium-sized Enterprises(SMEs) and Startups(MSS), Korea, under the “Regional Star-Enterprise Development Program(R&D, P0010142) supervised by the Korea Institute for Advancement of Technology(KIAT).
Effect of Solvent of Ionomer Dispersion on Porous Electrodes with Three Phase Boundary
Authors: Park Jong-Hyeok , Park Jin-Soo
Published: May 2020

Electrichemically driven energy conversion devices requires anodic and cathodic reactions to complete their electrochemical cells. Recent energy conversion devices such as water electrolyzers or fuel cells is comprised of anodic and cathodic reactions in which gases, ions and electrons participate. In particular, the movement of proton or hydroxyl ions generated and consumed at two electrodes, i.e., anode and cathode, are essential to determine the reaction rates due to low mobility compared to electrons. Ions moved through ion conducting membranes should be transported inside electrodes to participate in anodic or cathodic reactions. Ion pathway is normally in liquid electrolyte. Regardless, the introduction of any aqueous phase in energy conversion devices causes many problems during fabrication, operation, maintenance, and so on. In addition, if gas penetration or gas evolution is one of phenomena taking place at electrodes, the electrodes should be porous. Thus, much efforts have been devoted to develop quasi-solid electrolytes such as gel polymer, ion conducting polymers, impregnation of ions in porous matrix and so on. Among the candidates, ion conducting polymers are quite often chosen as ion conducting media for energy conversion devices. The technique to introduce ion conducting polymers within electrodes for oxidation and reduction reactions is to solidify catalyst inks consisting of electrocatalyst, dispersion of ion exchangeable polymers, controlling solvents and additives by evaporation of all solvents in catalyst inks. Ion conducting polymers could be dispersed in various solvents. It causes different shapes of ion conducting polymers in solvents, for instance, cylindrical rods, a less-defined large particles, coils and so on. Such different types of ion conducting polymers form distinguished structure catalyst layers. In this study, the effect of solvents dispersing ion conducting polymers on the performance and durability of catalyst layers was investigated. Electrochemical characterization such as I-V polarization, cyclic voltammetry, impedance and so on and microscopic characterization such as SEM and TEM were carried out to evaluate the performance and durability of catalyst layers.

Acknowledgments

This research was supported by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT, & Future Planning(NRF-2019M3E6A1063677).
Palladium-Based Nanostructures Supported on Graphene Oxide for Formic Acid Electro-Oxidation
Authors: Medina Rojano Victor Alberto , Landa Castro Midori , Montes de Oca Yemha María Guadalupe , Aldana-González Jorge , Estrada-Arce Elsa Miriam , Romero-Romo Mario Alberto , Palomar-Pardavé Manuel
Published: May 2020

Increments of significant Green House Gases emissions, GHG, due to persistent policies on continuing fossil fuel burning has led, in return, to more research on conversion, storage and distribution of sustainable energy sources. Direct Liquid Fuel Cells (DLFCs) coupled with Pd-based nanoparticles (PdNPs), as renewable energy sources, are capable of attaining relatively high energy conversion efficiencies, safety of operation and dependability; together, they can be applied to portable devices and transport means. For example, Direct Formic Acid Fuel Cells (DFACs) are used for these applications. This work deals with the synthesis of Pd-based electrocatalysts through a combustion method. Electrocatalysts were characterized by XRD and SEM. Further, the ensuing electrochemical characterization was carried out by means of the electrocatalysts activation, CO adsorption/oxidation and formic acid electro-oxidation.

Figure 1
Non-Pt Nanofibrous Catalysts for an ORR PEM Fuel Cell Cathode
Authors: Bompolaki Eftychia , Zhang Wenjing , Jensen Jens Oluf
Published: May 2020

Electrospun nanofibrous catalysts made of non-Platinum group metal (non-PGM), low cost precursors are studied for the ORR to be applied in a PEM fuel cell cathode. Optimizing the structure of proton exchange membrane (PEM) fuel cell cathodes is essential to reduce the high cathode loadings (1 to 6 mg of catalyst per cm2), used for non-PGM catalysts to compensate for the lower activity against standard Pt catalysts. Electrospinning is used to shape the catalytic precursors in a network of nanofibers to study the effect of the electrospun architecture with respect to fuel cell performance.
Poly(acrylic acid) Cross-Linked with Potassium As Gel Polymer Electrolyte in Small Zinc-Air Batteries
Authors: Díaz-Patiño Lucia , Ortiz-Ortega Euth , Trejo Gabriel , Guerra-Balcázar Minerva , Arriaga Luis G. , Álvarez-Contreras Lorena , Arjona Noé
Published: May 2020

Zn-air batteries are considered as a suitable alternative to typical batteries due to the zinc is a highly abundant and environmentally friendly material (exist more than 224 trillions of tons in the first mile of deep). However, zinc anode has several challenges to overcome such as shape changes, dendritic growth, passivation, and corrosion. Two strategies can be followed to decrease/eliminate these issues, one of them consists in the metallic electrode modification, and other in the electrolyte modification. In this work, poly(acrylic acid) cross-linked with potassium (PAAK) was used to develop gel polymer electrolytes (GPEs) in 6 M KOH with and without additives (CTAB), testing their effect on battery performances. PAAK at different weight percentages were evaluated, being 3 wt.% PAAK the most promising concentration displaying a battery performance similar to that displayed by an aqueous 6 M KOH solution (20 mW cm-2). Furthermore, SEM images after a discharge experiment for 4 h at 1.25 mA cm-2 followed by a charge process indicated that the zinc anode maintained its original shape (nanoflakes with thickness of tens of nanometers) in the Zn-air battery operated with the GPE. However, zinc anode suffered shape changes in the 6 M KOH aqueous electrolyte, forming hemispherical particles with sizes between 1 to 4 μm. Also, the battery tests with the GPE displayed a higher durability to that operated with 6 M KOH aqueous electrolyte.
Ternary Alloys AuPdPt Catalysts Supported on the Tungsten Carbide for Methanol Electrooxidation
Authors: Du Shengjuan , Lu Shun , Hummel Matthew , Nie Ming
Published: May 2020

Direct methanol fuel cell (DMFCs) is one of the best positioned toward widespread commercialization and the most viable alternative to lithium-ion batteries for portable applications. A major drawback of this technology is in large part related to the dependence on Pt-based electrocatalysts for methanol oxidation reaction (MOR) at the anode. To address this issue, low-Pt electrocatalysts are desired for keeping high performance of MOR. In this abstract, trimetallic AuPdPt nanocomposites supported on the tungsten carbide (WC) was prepared through two-step method, i) intermittent microwave heating method (IMH) and ii) direct chemical reduction method. Trimetallic AuPdPt nanoparticles are dispersed well on the nanostructured WC, confirmed by scanning electron microscopy (SEM), energy X-ray diffraction spectroscopy (EDX), and transmission electron microscopy (TEM). The electrocatalytical performance of the as-synthesized nanocomposite for MOR was tested using cyclic voltammetry and chronopotentiometry in alkaline media. The results revealed that the WC enhanced trimetallic AuPdPt nanocomposites has better performance of MOR and stability than that of commercial Pt/C catalyst. Alloying strategy and the introduction of WC support are good choices for preparation of MOR electrocatalysts with low loading of Pt.
MnOx Modified Fiber-Shaped Co As an Efficient Catalyst for Hydrazine Electro-Oxidation
Authors: Norkus Eugenijus , Valuckytė Gitana , Zabielaitė Aušrinė , Balčiūnaitė Aldona , Šimkūnaitė Dijana , Vaičiūnienė Jūratė , Naruskevicius Leonas , Tamašauskaitė-Tamašiūnaitė Loreta
Published: May 2020

In this study, MnOx modified fiber-shaped Co nanocomposites have been fabricated via electrochemical deposition with the aim to use them as electrocatalysts in direct hydrazine fuel cells (DHFCs). The electrocatalytic activity of the MnOx modified fiber-shaped Co nanocomposites towards the electro-oxidation of hydrazine in an alkaline medium has been investigated using cyclic voltammetry and chrono-techniques. Scanning Electron Microscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy have been used for the characterization of the surface morphology, structure and composition of the prepared catalysts.

It was found that the MnOx modified fiber-shaped Co nanocomposites have significantly higher catalytic activity towards the electro-oxidation of hydrazine as compared to that of the bare fiber-shaped Co. Moreover, modification of the fiber-shaped Co coating with MnOx leads to the rather pronounced shift in the hydrazine electro-oxidation potential to more negative potential region and is followed by a tremendous increase in the direct hydrazine oxidation rate as compared to that of the unmodified fiber-shaped Co coating. MnOx modified fiber-shaped Co nanocomposites seems to be an efficient anode catalyst for DHFCs.
Additional Carbon/Nafion Covering Layer on Electrode in Polymer Electrolyte Membrane Fuel Cell for Effective Operation at Low Relative Humidity Condition
Authors: Jang Segeun , Seol Changwook , Kang Yun Sik , Kim Sang Moon , Yoo Sung Jong
Published: May 2020

Demands for fuel cells that can operate in ambient conditions are increasing as their applications expand to portable devices and unmanned aircraft system. Particularly, maintaining high-hydration state of membrane electrode assembly (MEA) in the fuel cell in ambient condition is essential for prevention of performance degradation. At low relative humidity condition, the polymer electrolyte membrane exhibit poor ionic conductivity because the transfer of protons bonded with water molecules is severely limited. Therefore, developing the effective strategy to prevent dehydration in polymer electrolyte membrane fuel cell (PEMFC) is highly required. Herein, we successfully improve the MEA performance in low relative humidity condition by introducing a functional carbon-covering layer onto the catalyst layer on the cathode side. The carbon-covering layer plays an effective role to retain generated water and shows good compatibility with the MEA without interfering with the electrochemical reaction. Furthermore, we have investigated the optimized Nafion ionomer loading and the thickness of the carbon-covering layer for effective operation in both low and high relative humidity condition.

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Investigating the Performance of Tantalum Carbide Supported Iridium-Based Catalyst for Polymer Electrolyte Membrane Water Electrolysis
Authors: Mutambanengwe Rutendo Leah , Peppley Brant A
Published: May 2020

Hydrogen from polymer electrolyte membrane (PEM) water electrolysis has been identified as a key enabler for the transition to low/no-carbon energy from renewable energies. Polymer electrolyte membrane water electrolysis can be used to generate hydrogen from surplus energy generated using renewable energy technologies. Iridium is currently considered a state-of-the-art catalyst for the oxygen evolution reaction. However, it is a rare noble metal and as such a surge in demand would increase the cost of PEM water electrolyser units. One of the main strategies employed is the reduction of the noble metal loading through the use of supports. Tantalum carbide supported iridium based catalysts have been shown to be potential candidates for use as oxygen evolution reaction (OER) catalysts for water electrolysis. In this study, the performance of IrOx/TaC catalyst prepared using a surfactant mediated method is presented. IrOx/TaC catalysts were synthesized and fabricated into membrane electrode assemblies (MEAs). Nafion 115 was used as the membrane for the MEAs. Ir:TaC ratio was varied and its effect on the electrolyser performance was observed. The ionomer loading in the anode was also varied at the different Ir:TaC ratios and the performance observed. The elemental distribution of the IrOx/TaC was determined using scanning transmission electron microscopy (STEM)/energy dispersive spectroscopy (EDS). The conductivities of the catalysts and MEAs were also determined. Scanning electron microscopy (SEM) was used to analyse the morphology and elemental distribution of the electrode surfaces and the cross-section of the MEAs. The electrochemical performance of the MEAs was then tested in a single cell electrolyser equipped with an in-situ reference electrode. Current-voltage (I-V) curves were obtained potentiostatically at 80 °C. It was observed that while the fabricated MEAs had lower loading of iridium in the electrode, their performance was comparable with those found in literature.
Study on the Effect of Surface Area on the Oxygen Reduction Reaction Performance of Perovskite Catalyst for Lithium-Oxygen Batteries
Authors: Kim Ji Youn , Choi Yu Song , Ahn Tae-Young , Yu Hye-Ryeon , Cho Jang-Hyeon
Published: May 2020

Lithium oxygen batteries have been recognized as one of the next-generation power sources, capable of supplying power for a long time even in an independent extreme environment. In spite of the theoretical advantage, Li-O2 batteries face technical and economic challenges that must be addressed to promote them as commercially variable technologies for future energy system. Above all, battery performance largely depends on the activities of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) of the cathode during discharge and charge, respectively. The undesirable overpotential caused by sluggish reaction kinetics associated with the ORR and OER greatly limit the current performance of Li-O2 batteries, which must be improved by efficient catalyzing the reactions. Among the numerous catalysts, perovskite oxides have attention for candidate electro catalyst for Li-O2 batteries due to their high electronic/ionic conductivity, high electrochemical stability, and catalytic activity. Especially, La0.6Sr0.4Co0.2Fe0.8O3(LSCF) is considered as a typical catalyst for Li-O2 batteries, which can provide high oxygen surface exchange coefficient for fast kinetics at the gas/electrode interface. The surface area is significantly related on the ORR and OER performance, which influences on the active area for reactions. In this study, we have tried to utilize a simple high energy ball milling process to investigate the electrochemical properties of LSCF catalyst. Through the BET analysis, it was confirmed that the specific area significantly was increased after ball milling due to the reduced particle size, obtaining the optimized milling time with the higher ORR performance. The electrochemical activities have been measured with rotating disk electrode (RRDE) method. Well-ball milled LSCF catalyst has resulted in the enlargement of specific surface area and increased defective sites, which improve the catalytic activity.

To investigate the influence of LSCF oxides on the ORR process, the performance of composite electrode with LSCF catalyst in LITFSI in ether solvents has been compared with a carbon based cathode (carbon nano tube(CM130)). From the discharge results, the composite electrode showed the superior performance as well as higher specific capacitance (more than 1.6 times) than carbon based electrode dye to the altered transport and reaction kinetics due to LSCF. In this study, we have proposed the processes of obtaining a catalyst with optimal electrochemical properties through a relatively simple process and applied it to electrode for lithium oxygen batteries.