bluuebunny/crossref_metadata_2025 huggingface dataset:
Accelerated Degradation of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers: Performance Degradation and Steady State Liquid Water Distributions with in Operando Synchrotron X-ray Radiography
Authors: Liu Hang , George Michael Gerald , Ge Nan , Banerjee Rupak , Chevalier Stéphane , Lee Jongmin , Shrestha Pranay , Muirhead Daniel , Hinebaugh James , Zeis Roswitha , Messerschmidt Matthias , Scholta Joachim , Bazylak Aimy
Published: September 2016

As-received pristine gas diffusion layers (GDLs) were degraded through an accelerated artificial aging process by immersion into a 35% solution of H2O2 at 90°C for 12 hours. Polarization curves were obtained while synchrotron X-ray radiography was performed to investigate the effect of ageing on liquid water transport behavior. Peak output power density of the fuel cell composed of the aged GDL reached only 76% of that of the fuel cell composed of the pristine GDL. This performance degradation was attributed to an increase in mass transport resistance associated with liquid water accumulation at the aged GDL and flow field channel interface. The aged GDLs showed more liquid water accumulation at the microporous layer (MPL)/carbon substrate interface and carbon substrate regions than pristine GDLs at low current density operation. A fully developed water profile was established at lower current density for the aged GDLs compared to pristine GDLs.
Investigation of Ion Conductivity and ORR on Metal/Water Interfaces in Proton Exchange Membrane Fuel Cells
Authors: Hu Leiming , Zhang Muxing , Komini Babu Siddharth , Litster Shawn
Published: September 2016

The present work investigates the role of water on the ion conductivity and oxygen reduction reaction (ORR) performance of metal/water interfaces. Ionomer-free electrodes such as nanostructured thin film (NSTF) electrode have the potential to reduce the loading of platinum (Pt) for polymer electrolyte fuel cells (PEFCs). However, the proton transport mechanism is not well understood. To examine the dependence of ion conductivity and ORR performance on relative humidity (RH), two ionomer/binder-free metal surfaces, Pt and gold (Au), were measured at different RH conditions. The cyclic voltammetry (CV) shows that currents for the double layer, hydrogen and oxide species formation and reduction increase with increased inlet gas RH. This indicates that water films on the Au and Pt black surfaces play an essential role in ion conduction. The increased active area also yields increased ORR current density during fuel cell operation. The results indicate a significant thickness of the ionomer-free cathode is active despite the lack of ionomer.
Reaction and Mass Transport Simulation of Polymer Electrolyte Fuel Cell for the Analysis of the Key Factors Affecting the Output Performance in the Catalyst Layer
Authors: Kotoi Ryotaro , Inoue Gen , Kawase Motoaki
Published: September 2016

In order to reduce total cost of fuel cell vehicle (FCV), catalyst for polymer electrolyte fuel cell (PEFC) has been developed in recent years. However, the method for developing catalyst is trial and error, and the correlation between catalyst and the output performance is not clear. Our purpose is to reduce the cost of catalyst by analyzing key factors affecting the output performance in catalyst layers (CLs). In our previous studies, reaction and mass transport simulation method in the direction of through-plane was established. In addition to these, electrochemical reactions and radial mass transport phenomena in the catalyst in primary particle size were simulated in this study. The results suggest that Pt characters such as diameter and bearing position mainly improve the output performance in high voltage region (0.7 V - 0.9 V). Furthermore, the rate-determining step in the catalyst of primary particle size was oxygen diffusion in ionomer.
(Plenary) Challenges in Going from Laboratory to Megawatt Scale PEM Electrolysis
Authors: Danilovic Nemanja , Ayers Katherine E , Capuano Christopher , Renner Julie N , Wiles Luke , Pertoso Morgan
Published: September 2016

Renewable hydrogen is becoming an increasingly important component of the transition away from fossil fuel use and towards reduction in carbon dioxide production. Hydrogen is the intermediary between primary energy sources and end products in many chemical processes such as ammonia generation, refining, and biogas processing, and is currently mainly produced by reforming of natural gas. Hydrogen from electrolysis can both make a strong environmental impact on these industries and also improve utilization of intermittent renewable energy sources such as wind and solar by leveraging otherwise stranded resources. Proton exchange membrane (PEM) electrolysis is especially well suited to energy capture because of the dynamic range and ability to quickly ramp up and down from near zero output to full capacity. This paper will discuss the challenges in continued scale up, translating laboratory scale findings to commercial PEM systems as well as some of recent advancements and impact on cost.
(Invited) Self-Humidifying Membrane Electrode Assembly Prepared by Adding Moisture Preserve Materials in Anode Catalyst Layer
Authors: LIao Shijun , Hou Sanying
Published: September 2016

By adding moisture preserve materials in the anode catalyst layer, we prepared a series of low humidity membrane electrode assembly (MEAs), and all the MEAs exhibited excellent performances at low humidity for both anode fuel and cathode air. The types of the materials on the low humidity performances of the MEAs were investigated, and we also explored the mechanism for the excellent low-humidity performances of the MEAs with moisture preserve material added at anode catalyst layer.
Air Breathing PEM Fuel Cells in Aviation
Authors: Flade Steffen , Stephan Thomas , Thalau Oliver , Burberg Torben , Schirmer Johannes , Kallo Josef
Published: September 2016

Aviation industry and governing bodies have set out to significantly reduce the environmental footprint of aviation. This has led research groups to explore disruptive paths of innovation for aircraft and a trend to the electrification of onboard systems in more electric and all electric aircraft. Providing the required electric power using a fuel cell and battery hybrid architecture not only promises the reduction of carbon emissions and noise but also allows for system level optimizations using synergy effects from a multi-functional system-integration that aircraft design could benefit from. System voltage, power output and behavior depends on a number of parameters, like ambient pressure, temperature, requested amount of oxygen remaining in the cathode exhaust of the fuel cells, etc.. While small aircraft, like the HY4, are currently being or have been built using this technology, understanding this behavior is crucial to a successful application of fuel cells in aviation.
On-Board Hydrogen Powered Proton Exchange Membrane Fuel Cells
Authors: Akay Tunc Eren , Abdullayeva Nazrin , Sankir Mehmet , Demirci Sankir Nurdan
Published: September 2016

A novel approach will be presented here for the fast, safe and stable hydrogen generation for fuel cells. This was achieved by circulating the acid and the chemical hydride solutions which were separated by the disulfonated poly(arylene ether sulfone) copolymer membrane. Since the rate of proton transfer is a function of ion exchange capacity (IEC) and scales with the degree of disulfonation of membranes, tailoring the IEC of membranes is crucial during the hydrogen generation. Additionally, it was found that the type of acid and acid concentration influenced the hydrogen generation rates. The highest hydrogen generation rate was measured as 406 mL min-1 when sulfuric acid with the possible commercial available concentration of 18 M was used. At last but not least, proton exchange membrane fuel cell has been powered with the hydrogen generator developed in this study and has demonstrated continuous hydrogen generation more than 400 h.
Numerical Simulation of PEMFC Performance Considering Striped Wettability Distribution of GDL
Authors: Takaya Koji , Araki Takuto
Published: September 2016

A three-dimensional numerical model, which includes gas channels, gas diffusion layers (GDLs) with different wettability, catalyst layers in both the cathode and anode side, and a polymer electrolyte membrane, has been developed to investigate the water transport and power generating characteristics of a Proton exchange membrane fuel cell (PEMFC). In addition, the effectiveness of the hybrid GDL to reduce the liquid water saturation under flooding conditions was investigated by using our comprehensive model and was compared with the experimental results. The numerical liquid water distributions at the two different wettability regions in GDL were examined. The distribution of liquid water was more towards the hydrophilic regions due to the drawing of water from the hydrophobic regions. Furthermore, the performance of the PEMFC was improved by the combination of the hybrid GDL and the gas channels with micro-grooves. The efficiency of the PEMFC is discussed quantitatively in this paper.
Effect of Water Cluster Structure on Proton Transport in Proton-Exchange Membranes Using Reactive Molecular Dynamics Simulations
Authors: Mabuchi Takuya , Tokumasu Takashi
Published: September 2016

The effects of water cluster structures on proton transport properties have been studied using reactive molecular dynamics simulations. The proton diffusivity and proton distributions have been evaluated in the two hydrophilic cluster structures (i.e., the cylinder model and the lamellar model) that are the most typical proposed morphological models in polymer electrolyte membranes. The proton transport with the Grotthuss mechanism has been incorporated using the modified two-state empirical valence bond (aTS-EVB) model. The diffusion coefficients in each dimension are correlated with the cluster size as well as the type of cluster models. It is found that the proton diffusion coefficients strongly depend on the cluster model and its size. The proton distributions are also investigated to elucidate the proton pathway in each cluster model. Our simulation results provide insight into quantitative information about the water cluster structure dependence of the proton transport properties at an atomic level.
A Molecular Dynamics Study of Transport Properties in Degraded Nafion Membranes
Authors: Kono Susumu , Mabuchi Takuya , Tokumasu Takashi
Published: September 2016

In order to estimate the proton transport property of the degraded Nafion membrane, molecular dynamics simulations have been carried out. The degraded Nafion molecules are made by breaking side chains randomly. Degradation level is controlled by changing the number of broken side chains. In the simulation systems, there were four ten-unit degraded Nafion molecules and equimolar fragments generated by degradation in various conditions, such as different water contents and degradation levels. Density, diffusion coefficient, and number of water cluster have been evaluated. Our findings are, in the degraded Nafion membranes, water molecules and hydronium ions are more dispersed which suppresses Grotthus mechanism, and the system becomes much fluidity owing to the existence of various fragments which facilitates Vehicle mechanism.
Models to Couple Mechanics and Electrochemical Transport in Solid Electrolytes
Authors: Goyal Priyamvada , Monroe Charles W
Published: September 2016

A transport model for solid electrolytes, such as ionomer membranes used in fuel cells, is developed systematically from a model for liquid electrolytes. The paper discusses thermodynamic considerations necessary to make this adapted system internally consistent, and delineates the challenges that come with it. The ability of solids to sustain an external force makes the study of transport in them crucially different from that in liquids, especially in the context of constrained swelling of fuel cell membranes. The possibility of sustaining a pressure distribution in such solid electrolyte systems demands sophisticated handling of mechanics and its local coupling with transport. The structure of a closed generalised model with important new features is presented, numerically applied to the simple case of uniform pressure, and validated against analytical results.
Computational Modelling of Cationic Contamination in PEFCs: a Multiphase Mixture Approach
Authors: Banas Charles Joseph , Pasaogullari Ugur
Published: September 2016

Cationic contamination of polymer electrolyte fuel cells (PEFCs) is dependent on a liquid water transport mechanism as the cations transport with the liquid water to reach the polymer membrane. A steady state, one dimensional, multiphase model is developed to examine the role of a hydrophobic microporous layer in the transport of liquid water across a two layer gas diffusion media (GDM). At low current density operation (0.2A/cm2), an evaporation front occurs within GDM as water enters the hydrophobic zone, preventing cations from reaching the cathode catalyst layer.
Correlation between the Swelling Characteristic and Humidity Cycle Durability of a Polymer Electrolyte Membrane
Authors: Hashimasa Yoshiyuki , Daitoku Hiroshi , Numata Tomoaki , Matsuda Yoshiyuki
Published: September 2016

Thermal mechanical characteristics of sulfonated polyether sulfone (SPES) and NR211 polymer electrolyte membranes were evaluated by dynamic mechanical analysis and thermal mechanical analysis with and without catalytic layers in several humidity conditions. Swelling test and humidity cycle test were also conducted using single-cells to examine any correlation between the humidity cycle life and thermal mechanical characteristics of the polymer electrolyte membranes. The humidity cycle durability of SPES was much lower than NR211 though the SPES showed higher storage modulus in wide range of humidity. Swelling test showed that SPES had stronger tendency of swelling deformation especially in surface direction compared to NR211. These results suggest that suppressing its physical swelling under humid conditions is considered to be more effective in improving the humidity cycle durability rather than increasing the storage elastic modulus.
Determining Membrane Degradation in Polymer Electrolyte Fuel Cells by Effluent Water Analysis
Authors: Bodner Merit , Rami Mija , Marius Bernhard , Schenk Alexander , Hacker Viktor
Published: September 2016

Membrane degradation is a key issue limiting the lifetime of polymer electrolyte fuel cells. Thus, it is essential for the commercialization of fuel cells to prevent the decomposition of the polymer electrolyte. Therefore, a fundamental knowledge of the underlying mechanisms is required. Membrane degradation is often quantified by the emission of fluoride ions, yet polymer fragments can be released with the effluent water as well and cannot be detected by common means, such as the fluoride ion selective electrode. Therefore, effluent water treatment was conducted to allow a quantitative detection.
Cerium Migration in Polymer Electrolyte Membranes
Authors: Baker Andrew M. , Mukundan Rangachary , Spernjak Dusan , Advani Suresh G. , Prasad Ajay K. , Borup Rod L.
Published: September 2016

Cerium migration was induced in polymer electrolyte membranes (PEMs) and subsequently characterized using X-ray fluorescence. The effects of proton flux and relative humidity on cerium migration were evaluated using H2 pump operation in a standard conductivity cell. After 6 Coulombs of charge transfer, cerium in the region between the cell electrodes was reduced by > 75% and was increased in the region under the counter electrode by a factor of 8. In addition to charge transfer, a secondary PEM hydration effect is discussed. Proton/water flux resulted in rapid migration compared to the effects of concentration gradients. Reversible migration is also demonstrated in an uncatalyzed PEM, however, the presence of catalyst layers results in cerium stabilization in the electrodes.
Synthesis and Evaluation of Core-Shell Electrocatalysts for Oxygen Reduction Reaction
Authors: Zhu Shangqian , Yue Jeffrey , Qin Xueping , Shao Minhua
Published: September 2016

Cu-mediated-Pt-displacement method that involves the displacement of an underpotentially deposited (UPD) Cu monolayer by Pt has been extensively studied to prepare core-shell catalysts. It has been found that Pt clusters instead of a uniform Pt monolayer were formed in the gram batch synthesis. With a suitable surfactant, such as citric acid, the Pt shell could be much more uniform. In this study, the role of citric acid in controlling the Cu-Pt displacement reaction kinetics was studied by electrochemical techniques. It was found that the strong adsorption of citric acid on Pd, Pt, Cu/Pd, and Pt/Pd surfaces could slow down the Cu-Pt displacement reaction and lead to a more uniform Pt layer. The synthesized Pd@Pt core-shell catalyst had a 4.8 times higher mass activity (0.95 A mg−
1 at 0.9 V) and better stability than commercial Pt/C in the liquid cell test.
Electrochemical Degradation of Nafion Ionomer to Functionalize Graphene as a Support for Core-Shell Palladium-Ruthenium Alloy @ Platinum Electrocatalysts
Authors: Kuo Chih-Chia , Chang Yu-Chen , Chou Chao-Lin , Chou Shih-Cheng , Wu Pu-Wei
Published: September 2016

A simple but effective electrochemical route to functionalize graphene is demonstrated. Cyclic voltammetric sweeps are performed in H2SO4 aqueous solution on electrodes containing carbon cloth, graphene, and Nafion ionomer. With supply of ambient oxygen, the formation of hydroxyl radicals from the oxygen reduction reaction during CV cycles initiates the decomposition of Nafion ionomer that engenders oxygenated functional groups on the graphene surface. Raman analysis suggests a minor change for the graphene structure. Exploring various amounts of Nafion ionomer, we determine the optimized conditions for graphene functionalization. Contact angle is used to evaluate the effect of Nafion ionomer decomposition. X-ray photoelectron spectroscopy is employed to study relevant functional groups. Afterwards, nanoparticles of Pd9Ru are synthesized and impregnated on those functionalized graphene (FGN) via a wet chemical reflux process. X-ray diffraction patterns of the as-synthesized samples suggest successful formation of alloy. Images from transmission electron microscope confirm the average size of 3-4 nm. As expected, the Pd9Ru alloy are much more dispersive in FGN rather than in the one without functionalization.
Enhanced Stability of Novel Hierarchical Carbon Supports in PEMFC Application
Authors: Sepp Silver , Nerut Jaak , Vaarmets Kersti , Kanarbik Rait , Tallo Indrek , Kurig Heisi , Lust Enn
Published: September 2016

The stability of a polymer electrolyte membrane fuel cell (PEMFC) catalyst depends strongly on the selection of an appropriate support material. The instability of carbon supports in fuel cell working conditions is the major obstacle hindering the large scale commercialization of PEMFCs. Hierarchical microporous-mesoporous carbon supports with high specific surface area and well-defined properties were prepared from molybdenum carbide using the high temperature chlorination method. The synthesized Pt-C catalysts were used to prepare electrodes for the PEMFC single cell measurements. The polarization curves and chronopotentiometric measurements were conducted to evaluate the activity and stability of the catalyst materials synthesized. It was found that the carbon synthesized from molybdenum carbide at 750 °C is suitable for PEMFC application having better PEMFC activity and stability (cell potential degradation 240 µV h−1) than commercial carbon support Vulcan XC72 (670 µV h−1) based single cell.
IL-FE-SEM and ICP-MS Study for Degradation of Pt/C Catalyst
Authors: Kinumoto Taro , Ikeyama Misako , Matsuoka Miki , Tsumura Tomoki , Toyoda Masahiro
Published: September 2016

The degradation of Pt/C in HClO4 solution was investigated using identical location field emission scanning electron microscopy (IL-FE-SEM) and inductively coupled plasma-mass spectrometry (ICP-MS) during potential pulse acceleration degradation tests (ADT). Typical morphological changes such as particle shrinkage and growth, disappearance, migration, coalescence, and precipitation on the carbon support were observed for Pt particles. The precipitation was a minor part of the deterioration process and was observed after the 5,000th pulse. The largest number of particles either disappeared or shrunk. Hence, these processes were considered to be the largest contributors to deterioration under the ADT. In addition, the migration distance of the Pt particles was generally less than 4 nm.
ORR Properties for Model Pt-Shell Layers Prepared on Nitrogen-Beam Irradiated Pt25Ni75(111) Substrate
Authors: Asano Masato , Kawamura Ryutaro , Todoroki Naoto , Wadayama Toshimasa
Published: September 2016

We evaluated the oxygen reduction reaction (ORR) properties of ultra-thin Pt shell layers prepared on nitrogen ion beam (N2
+ beam), and neutralized nitrogen ion beam (N2
0 beam) irradiated Pt25Ni75(111) substrates. Although the non-N2 irradiated 0.9-nm-thick Pt layers on Pt25Ni75(111) (Pt0.9nm/Pt25Ni75(111)) showed a kinetic-controlled current density (j
k) of 7.7 mA/cm2, the j
k values for the Pt0.9nm/N2
+–Pt25Ni75(111) and Pt0.9nm/N2
0–Pt25Ni75(111) pristine surfaces are 6.6 and 6.3 mA/cm2, respectively. In contrast, the N2
0 beam irradiated sample displayed better durability by retaining ca. 90% of the initial j
k value, while the j
k values for the N2
+ irradiated and non-irradiated samples decreased to ca. 70% and 60%, respectively, of the initial value. The result suggests that N2
0 beam irradiation on the Pt25Ni75(111) substrate is effective for the electrochemical stabilization of the ultra-thin Pt-shell layers.
SnO2-Supported Electrocatalysts on Conductive Fillers for PEFCs
Authors: Nakazato Yoshiki , Iwami Masahiro , Okumura Makito , Noda Zhiyun , Hayashi Akari , Sasaki Kazunari
Published: September 2016

Electrocatalyst layer in polymer electrolyte fuel cells (PEFCs) has complicated 3D nanostructure, and control and optimization of the structure are essential for higher cell performance. Carbon black supported cathode catalyst is widely used, whilst carbon support can be degraded through electrochemical oxidation on the cathode side. The use of Nb-doped SnO2 supports for Pt electrocatalysts prevents support corrosion, while the use of carbon nanotube (CNT) based conductive fillers assists electronic transport in the electrocatalyst layers. High I-V performance of membrane electrode assemblies (MEAs) using stable SnO2 supports deposited on conductive CNT fillers is successfully demonstrated under the strongly acidic PEFC operational condition.
Estimation of the Rate Constants for the 2x2-Electron ORR by Combining the Voltammograms of O2 and H2O2 Reduction Reactions
Authors: Muthukrishnan Azhagumuthu , Nabae Yuta
Published: September 2016

A modified-Damjanovic model was developed in order to estimate the real rate constants from the overestimated ones of the conventional Damjanovic model on the Fe-N/C catalyst. The metal-free N/C catalyst did not show good catalytic activity towards H2O2 reduction reaction, indicating the need of Fe for the follow up H2O2 reduction reaction in the 2×2-electron ORR. The H2O2 reduction rate constants on Fe-N/C catalyst were used to extract the real rate constants.
Metal Phosphide-Based Novel Anodes for Intermediate Temperature Fuel Cells
Authors: Kikuchi Ryuji , Ataku Takahiro , Takagaki Atsushi , Oyama Shigeo Ted
Published: September 2016

In this study, metal phosphides such as Ni2P, CoP, FeP, WP, and MoP were investigated as novel anode catalysts for intermediate temperature fuel cells. Composite electrolytes composed of CsH2PO4 and SiP2O7, the metal phosphates, and a commercial Pt/C electrode were used as the electrolyte, anode, and cathode, respectively, and power generation characteristics were evaluated at 220ºC as H2-O2 fuel cells. The anode performance was compared based on the electrochemical surface area of each anode determined by cyclic voltammetry. Among the phosphide anodes, the MoP catalyst exhibited excellent current-voltage characteristics, and demonstrated a potential as an anode catalyst superior to the Pt/C catalyst.
Facile Synthesis of High Performance Platinum-Cerium Oxide Nanocatalysts for Methanol Oxidation
Authors: Valk Peeter , Nerut Jaak , Kanarbik Rait , Lust Enn
Published: September 2016

In this study, platinum-cerium oxide nanoparticles synthesised from CeNO3 and H2PtCl6 solutions in ethylene glycol using microwave heating method, exhibited high activity towards methanol electrooxidation. The materials were electrochemically characterised using cyclic voltammetry and rotating disk electrode methods, and physically characterised using X-Ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-Ray spectroscopy (SEM-EDX). The methodology of the synthesis of the materials was straightforward and resource efficient. SEM-EDX data indicated that the synthesised nanocatalysts have a very uniform dispersion on the catalyst support material, and a narrow particle size distribution. The synthesised nanocatalysts had a low overpotential towards methanol electrooxidation and high currents for methanol and carbon monoxide oxidation.
Synthesis of Metal-Free Electrocatalyst Obtained from Different Biomass Sources with High Performance for Oxygen Reduction Reaction in Fuel Cells
Authors: Alonso-Lemus Ivonne Liliana , Escobar-Morales Beatriz , Rodríguez-Varela Fransico Javier , González-Quijano Diego , Lardizabal Daniel , Pacheco-Saucedo Kehila , de la Torre Saenz Luis
Published: September 2016

In this work, the synthesis and characterization of novel metal-free electrocatalysts obtained from biomass source is reported. Sargassum and waste leather has been subjected to simple thermochemical treatments, obtaining high performance electrocatalysts for the Oxygen Reduction Reaction (ORR) in KOH. A higher catalytic activity has been determined for the electrocatalyst from leather (PAL), compared to electrocatalyst obtained from sargassum (PAS). Furthermore, PAL delivers a higher current density compared with commercial 20% Pt/C (j = 9.0 and 4.5 mA cm-2, respectively), while its on-set potential shifts only 145 mV to more negative values. The metal-free catalysts are a promising eco-friendly and scalable alternative as cathode materials for alkaline fuel cells and other electrochemical energy devices.
(Invited) Engineering Modeling of PEM Water Electrolysis: A Survey
Authors: Bensmann Boris , Hanke-Rauschenbach Richard
Published: September 2016

The present contribution tries to give a brief survey on state of the art modeling of water electrolyzers based on proton exchange membranes (PEM). First attempts to describe their operating behavior by means of mechanistic models have been carried out in the early 1990ies by Millet (e.g. [Millet, Electrochimica Acta 36 (1991), p. 263] and Goldberg et al. [Goldberg et al., Journal of Applied Electrochemistry 22 (1992), p. 1147]). Since then a few dozens of further papers dealing with this subject have been published, most of them in the last decade. Those papers have been carefully analyzed and are discussed with regard to the considered phenomena in each of the functional layers of the electrolyzer.
Gas Crossover Suppression by Controlling Wettability of Cathode Current Collector
Authors: Ito Kohei , Sakaguchi Takuya , Tsuchiya Yuta , Inada Akiko , Nakajima Hironori , Saito Ryo
Published: September 2016

Hydrogen gas crossover, which reduces current efficiency, is critical issue in high pressure PEMWE (Polymer Electrolyte Membrane Water Electrolysis). This study proposes controlled wettability current collector, which enhances the detachment of hydrogen gas bubble from the current collector and decreases the crossover. A high pressure operation of a PEMWE cell with visualization clarified that the wettability impacts on the bubble dynamics and changes the current efficiency. Among the current collectors prepared, hydrophilic one indicated higher current efficiency and suggested smaller crossover.
Preparation of Iridium-SnO2/VGCF Electrocatalysts for Water Electrolysis
Authors: Anai Hiroki , Matsuda Junko , Noda Zyiyun , Tachikawa Yuya , Hayashi Akari , Ito Kohei , Sasaki Kazunari
Published: September 2016

Novel iridium-based electrocatalysts supported on SnO2/Vapor-Grown Carbon Fiber (VGCF) have been developed and characterized by FESEM, STEM, and XPS. The membrane electrode assembly (MEA) made with the IrO2/Sn0.98Nb0.02O2/VGCF electrocatalyst exhibited a decrease in overvoltage especially under the low current density compared to the MEA made with conventional IrO2/Ti electrocatalyst. Iridium-based SnO2/VGCF can be a good candidate for anode catalysts of water electrolysis cells.
Steps Towards Reactive Hydrogen Pumping
Authors: Fane Brian , Goenaga Gabriel A. , Zawodzinski Thomas A.
Published: September 2016

In this contribution, we provide some preliminary studies of mediator electrochemistry for oxidative breakdown of organic feedstock. The electrochemistry of phosphomolybdic acid is probed by cyclic voltammetry, RDE voltammetry and polarization experiments. Phosphomolybdic acid reacts readily on carbon surfaces under conditions similar to those in which it shows oxidative activity for biomass.
Separation and Characterization of Overpotentials in Electrochemical Hydrogen Pump with a Reference Electrode
Authors: Hao Yan Ming , Nakajima Hironori , Inada Akiko , Sasaki Kazunari , Ito Kohei
Published: September 2016

Overpotentials included in electrochemical hydrogen pump is separated with using a reference electrode. Separation result shows that non-ohmic overpotential in cathode is larger than that in anode. This result is also confirmed by electrochemical impedance spectra measurement, which shows impedance spectra of cathode is larger than that of anode. Volmer-Heyrovsky-Tafel mechanism is used to explain the separation result. Simulation result with using this mechanism suggests that reactions in anode and cathode are dominated by different mechanisms, and reaction rate of cathode is 2 orders of magnitude slower than that of anode.
Gas Crossover Mitigation in PEM Water Electrolysis: Hydrogen Cross-over Benchmark Study of 3M's Ir-NSTF Based Electrolysis Catalyst-Coated Membranes
Authors: Bessarabov Dmitri , Kruger Andries , Luopa Sean M. , Park Jiyoung , Molnar Attila A. , Lewinski Krzysztof A.
Published: September 2016

In this work we present some preliminary data, such as permeability (gas crossover) of oxygen and hydrogen as a function of current density and other operational variables, aimed at establishing baselines for unmitigated hydrogen crossover of 3M’s electrolyzer MEAs based on 3M’s NSTF low-PGM loading catalyst and several types of perfluoro sulfonic acid based PEM membranes, both of which are widely commercially available (such as Nafion™ membranes), and membranes made by 3M. Experimental challenges associated with ex situ and in situ gas crossover measurements will be also discussed.
Methods for Determining the Working Electrode Interfacial Area for Electroanalytical Measurements of Metal Ions in Molten LiCl-KCl
Authors: Rappleye Devin , Horvath David , Wang Zhonghang , Zhang Chao , Simpson Michael Forrest
Published: September 2016

In this paper, we present an empirical evaluation of methods for determining the interfacial area between a working electrode and molten salt—specifically demonstrated using the eutectic LiCl-KCl system. Approaches studied include dipping a cold electrode into the molten salt, using a vertical translator to adjust the height of the electrode, partially coating the electrodes with an insulating material, and integrating a pre-peak which may represent formation of a monolayer of metal on the electrode. Salt mixtures investigated include LiCl-KCl-UCl3, LiCl-KCl-UCl3-MgCl2, LiCl-KCl-LaCl3-GdCl3, and LiCl-KCl-LaCl3-MgCl2. With accurate determination of the electrode-salt interfacial area, concentration correlations can be developed with error below 2%.
Dy Permeation through an Alloy Diaphragm Using Electrochemical Implantation and Displantation
Authors: Konishi Hirokazu , Oishi Tetsuo , Nohira Toshiyuki , Ono Hideki , Takeuchi Eiichi
Published: September 2016

We have been developing a new process for the separation and recovery of rare earth metals using molten salt electrolysis and an alloy diaphragm. In this study, the Dy permeation experiment was conducted with two kinds of electrolytic cell. The amount of permeated Dy and Nd increased corresponding to the amount of electricity. The Dy/Nd ratio was not so high. The current due to alloy formation and anodic oxidation of Dy were measured individually using two potentio/galvanostats. DyCl3 was added into LiCl-KCl eutectic melts and Dy was permeated through a DyNi2 diaphragm film by potentiostatic electrolysis. The current density was max 280 Am-2 and the current efficiency was max 98 %.
Characteristics of Capacitors Based on Ionic Liquids: From Dielectric Polymers to Redox-Active Adsorbed Species
Authors: Lust Enn , Siinor Liis , Kurig Heisi , Romann Tavo , Ivaništšev Vladislav , Siimenson Carolin , Thomberg Thomas , Kruusma Jaanus , Lust Karmen , Pikma Piret , Anderson Erik , Grozovski Vitali , Palm Rasmus , Läll Laura , Ruzanov Anton , Tooming Tauno , Oll Ove , Jänes Alar
Published: September 2016

Influence of chemical composition of ionic liquids and their mixtures on the electrical double layer characteristics of the cupercapacitors (EDLC) has been studied by cyclic voltammetry, electrochemical impedance spectroscopy, constant current charge-discharge and constant power discharge methods. It has been shown that addition of 1-ethyl-3-methylimidazolium iodide (EMImI), EMImBr or EMImCl to EMImBF4 increases differential capacitance. D-glucose and TiC have been used for preparation of the carbon powders. Additional thermal pyrolysis and/or carbon dioxide activation steps were applied for activation of the electrode materials. The EDLCs based on EMImBF4 + 5 wt% EMImI demonstrated nearly 50% higher stored charge than those with pure EMImBF4. Noticeable increase in specific capacitance up to 245 F g-1 at 1.0 V, specific energy (36.7 Wh kg-1) and specific power (30 kW kg-1), and minor increase in characteristic relaxation time constant (from 1.45 s to 1.48 s) has been established for EDLCs containing EMImI.
The Effect of Lengthening Cation Ether Tails on Ionic Liquid Properties
Authors: Lall-Ramnarine Sharon , Rodriguez Chanele , Fernandez Rahonel , Zmich Nicole , Fernandez Eddie , Dhiman Surajdevparkash , Wishart James F.
Published: September 2016

In order to explore the effect of multiple ether functionalities on ionic liquid properties, a series of ten pyrrolidinium ionic liquids and ten imidazolium ionic liquids bearing ether and alkyl side chains of varying lengths (4 to 10 atoms in length) were prepared. Their physical properties, such as viscosity, conductivity and thermal profile were measured and compared. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidinium ILs increases there is hardly any increase in the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. These results provide significant insight on the choice of starting materials for researchers designing ILs for specific applications.
An Ionic Liquid Consisting of Crown Ether – Coordinated Hydronium Cation and Amide Anion
Authors: Takeoka Shun , Kitada Atsushi , Fukami Kazuhiro , Murase Kuniaki
Published: September 2016

We first report an ionic liquid (IL) that consists of hydronium (H3O+) ion encapsulated by 18–crown–6–ether (18C6) and an amide anion. The composition of the crown ether–coordinated hydronium amide IL was estimated to be as [H3O+•18C6][Tf2N–]. The presence of H3O+ was revealed from the characteristic bands of the hydronium ion present in the infrared spectra. The melting point of [H3O+•18C6][Tf2N–] was 68–70 °C. At 70 °C, the viscosity of [H3O+•18C6][Tf2N–] was 39.5 mPa s, the conductivity was 1.9 mS cm–1, and the density was about 1.32 g cm–3. These bath properties of [H3O+•18C6][Tf2N–] were similar to those of common ILs at room temperature.
Electrochemical and Thermodynamic Properties of Lanthanum in a Chloride Melt – Liquid Metal System
Authors: Dedyukhin Alexander S. , Shchetinskiy Andrey V. , Kharina Ekaterina A. , Shchepin Ivan E. , Volkovich Vladimir A. , Yamshchikov Leonid F. , Osipenko Alexandr G.
Published: September 2016

The behavior and properties of lanthanum in a “molten salt – liquid metal” system in relation to pyrochemical reprocessing of spent nuclear fuels was considered. Temperature dependencies of lanthanum formal standard electrode potential E*
La/La(III) and Gibbs free energy change of lanthanum trichloride formation in LiCl–KCl–CsCl eutectic based melts were obtained between 668–976 K. Also the behavior of lanthanum was studied in Ga–Al (1.6 wt. % Al) and Ga–Zn (3.64 wt. % Zn) eutectic based metallic alloys, and activity, solubility and activity coefficients of lanthanum determined.
Electrodeposition of Al-W Alloys in AlCl3-NaCl-KCl Molten Salt Containing WCl4
Authors: Sato Kazuki , Matsushima Hisayoshi , Ueda Mikito
Published: September 2016

To form Al-W alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl melt containing WCl4 at 423 K. The voltammogram showed two cathodic waves at 1.1 V and 0.5 V vs. Al/Al(III), which may correspond to the reduction from W(IV) to W(III) and from W(III) to tungsten metal, respectively. Electrodeposits of Al and W were obtained in the range from -0.05 to 0.4 V and the highest concentration of W in the electrodeposit was 95 at% at 0.4 V. With increasing W content in the alloy, the morphology of the electrodeposits became more powdery and the particle size smaller.
Electrochemical Synthesis of Nanomaterials in Molten Salts
Authors: Kuznetsov Sergey A.
Published: September 2016

The possibility to synthesize TaO using the CsCl-K3TaOF6 melt has been shown. TaO crystallizes at the cathode as nanoneedles together with other tantalum compounds. It was found that TaO can be obtained by electrolysis of molten salts only at temperatures below 810 oC.
A Spectroscopic and Electrochemical Study of Molybdenum(IV) and Tungsten(IV) Species in Alkali Chloride Melts
Authors: Ivanov Alexander B. , Volkovich Vladimir A. , Pukhov Mikhail A. , Podlasova Kristina O. , Poskryakov Dmitry A. , Vasin Boris D. , Griffiths Trevor R.
Published: September 2016

Speciation and electrochemical properties of molybdenum(IV) and tungsten(IV) species were investigated in NaCl–CsCl, NaCl–KCl–CsCl and LiCl–KCl–CsCl eutectic based melts between 500–900 oC. Metallic tungsten dissolves anodically, yielding W(IV) ions that are prone to oxidation upon prolonged contact with silica. Electrode potentials of tungsten in fused chlorides were measured. Electronic absorption spectra of the melts containing the products of anodic dissolution of tungsten were recorded. Mo(IV) ions can be formed by reacting molybdenum dioxide with hydrogen chloride or by anodic oxidation of Mo(III) ions. Electronic absorption spectra of Mo(IV) species were recorded and Mo(III)/Mo(IV) red-ox potentials were estimated.
Probing Ionic Liquid/Electrode Interfaces by Hyperspectral Imaging
Authors: Malik Muhammad Kasim , Chrestenson Jacob R , Parr Daniel , Gray David , Mitiku H , Kahila Thomas , Malinowski Aleksander , Sánchez José , Haverhals Luke M.
Published: September 2016

Understanding the interface between ionic liquids (ILs) and electroactive surfaces is of great importance for a wide range of applications including batteries, capacitors, and sensors. In this work, we discuss analyses and characterization of the structure and dynamics of the electric double layer (EDL) by surface-enhanced infrared absorption spectroscopy (SEIRA). In particular, we are interested in developing a high throughput imaging version of the SEIRA consisting of a quantum cascade laser coupled to a hyperspectral imaging camera detector. Rather than generating single spectra at a time for single experiments, hyperspectral imaging techniques can be utilized to both increase signal to noise for capturing rapid dynamics while multiplexing experiments simultaneously. We are particularly interested in IL systems which exhibit hysteresis at interfaces. That is, systems for which interfacial structure is dependent on past events. Here, we discuss several cases studies and some preliminary findings.
Electrodeposition of Si Film from Water-Soluble KF-KCl Molten Salt and Feasibility of SiCl4 as a Si Source
Authors: Yasuda Kouji , Saeki Kazumi , Maeda Kazuma , Nohira Toshiyuki , Hagiwara Rika , Homma Takayuki
Published: September 2016

Toward an establishment of a new production method of solar cell substrates, electrodeposition of Si was investigated in molten KF–KCl (eutectic composition, 45:55 mol%) after the introduction of SiCl4. Gaseous SiCl4 was directly introduced into the molten salt at 1023 K by a vapor transport method using Ar carrier gas. The dissolution ratio of SiCl4 exceeded 80% even with the use of a simple tube for the bubbling. Galvanostatic electrolysis was conducted at 923 K on a Ag substrate at 155 mA cm−2 for 20 min in molten KF–KCl after the dissolution of 2.30 mol% SiCl4. Although compact Si layer was formed, the smoothness was lower compared to that obtained from the melt after the addition of K2SiF6. The anionic molar fraction is probably one of the factors affecting the morphology of deposit.
Thin-Layer Electrodeposition of Thorium and Uranium from Molten LiCl-KCl
Authors: Stika Milan , Chaiken Max , Jarrell Joshua , Blue Thomas , Cao Lei Raymond , Simpson Michael Forrest
Published: September 2016

A scheme for analyzing concentration of actinide isotopes in the molten salt electrolyte of nuclear fuel electrorefining systems is currently being developed based on alpha spectroscopy. The objective is to determine elemental and isotopic composition in molten salts in near real-time. Electrodeposition of a thin actinide layer directly onto a semi-conductor substrate is needed to overcome low penetration power of alpha particles. Techniques for making a good quality actinide metal deposit are described.
Pd Nanoparticle Formation during Constant Potential Electrodepositions in Ionic Liquids
Authors: Shrestha Sujan , Nagib Miyan , Biddinger Elizabeth J
Published: September 2016

The palladium film deposited on a nickel substrate in 1-butyl-1-methylpyrrolidinium dicyanamide using a constant potential electrodeposition method was shown to be composed of nanoparticles under transmission electron microscopy. The electrodeposition was carried out by applying a potential hold of -2.3 V vs Fc/Fc+ for 16 h. The size distribution of palladium nanoparticles was unimodal and narrow with an average size of 6.3 ± 1.6 nm. The Pd nanoparticles were polycrystalline with (111) plane being the most prevalent. The implications of this include the having to reconsider the properties of electrodeposited Pd thin films from ionic liquids and opening further applications of electrodeposition of Pd to include nanoparticle synthesis.
Natural Fiber Welding of Chitin and Chitosan on a Cotton Cloth Substrate: Novel Materials Displaying Antimicrobial Properties
Authors: Russell Robert Allen , Fox Eric T , Nolan Robert , Chandler Molly , Head Audrey C. , Brusoski Michael , De Long Hugh C , Trulove Paul C
Published: September 2016

Chitin and chitosan are biopolymers known to have natural antimicrobial properties. The ionic liquid (IL) based process of Natural Fiber Welding (NFW) was used to integrate chitin and chitosan into and between the fiber surfaces of cotton cloth. The NFW coating process was evaluated using scanning electron microscopy. The antimicrobial properties of the NFW coated cloths was investigated using E.Coli transfected with Green Fluorescent Protein. Confocal fluorescence microscopy (CFM) showed that both chitin and chitosan coatings inhibited microbial growth with the level of the inhibition increasing with longer NFW.
Resistive Sensors Based on Self-Assembled Core-Shell Nanoparticles
Authors: Baklouti Linda , Rajoua Khalil , Favier Frederic
Published: September 2016

Au@Ag, Au@ZnO and Au@SnO2 nanoparticles were synthetized and then assembled by Langmuir Blodgett technique. The resulting close-packed core-shell nanoparticle monolayers were transferred onto glass chips to fabricate NH3 and H2 resistive sensors. Sensing performances of the as fabricated sensors were evaluated through the resistivity changes in the discontinuous particle assemble. The sensitivity of Au@Ag based sensor was tested towards NH3 while Au@ZnO and Au@SnO2 based sensors were tested under H2. Assembles of core-shell nanoparticles organized by the Langmuir-Blodgett technique demonstrated attractive sensing performances towards the target gases in extended concentration ranges.
A Three Electrode Mixed Potential Sensor for Gas Detection and Discrimination
Authors: Tsui Lok-kun , Benavidez Angelica D , Palanisamy Ponnusamy , Evans Lindsey , Garzon Fernando H
Published: September 2016

A major goal for sensors in the automotive exhaust emissions control and monitoring field is the development of a single sensor to monitor NOx, NH3, CO, and hydrocarbons. Mixed potential electrochemical sensors can be readily tuned to be selective towards different gas mixtures by changing the composition of their electrode or applying a voltage or current bias. We have developed a three-electrode sensor comprised of Pt, La0.8Sr0.2CrO3 (LSCO), and Au0.5Pd0.5 electrodes with a porous (Yttria-stabilized Zirconia) YSZ electrolyte which can detect single and binary gas mixtures of NO, C3H8, and CO. The sensitivity of the electrode pairs were investigated and it was found that AuPd+Pt was most sensitive to CO while LSCO+Pt is best at detecting C3H8. From the sensor responses, we have trained artificial neural networks to use the voltage responses to recover the gas concentrations and classify the gas mixtures.
High Performance of SnO2-Based Gas Sensor by Introducing Perovskite-Type Oxides
Authors: Shimanoe Kengo , Ma Nan , Oyama Tokiharu , Nishibori Maiko , Watanabe Ken
Published: September 2016

Sensing layer mixed perovskite oxide, La0.1Sr0.9Co0.4Fe0.6O3-

δ

(LSCF), and Pd-loaded SnO2 nanoparticles (LSCF@Pd-SnO2) was deposited on the membrane of MEMS device by injection method, and its gas sensing properties to reducing gases and VOCs were investigated by heating sensor in pulse mode with heaters in ON and OFF state for one second repeatedly. The MEMS sensor showed fast response, high sensitivity and stability to 200 ppm C7H8 at 250°C by pulse heating with extremely low power consumption.
Electrochemical Detection of Hydrogen Using Two-Dimensional Carbon Nanosheets
Authors: Miyamoto Azumi , Kuwaki Yuta , Hatakeyama Kazuto , Armando Quitain , Sasaki Mitsuru , Matsumoto Yasumichi , Kida Tetsuya
Published: September 2016

Graphene oxide (GO) nanosheets with high protonic conductivity were used for electrochemical detection of hydrogen. The sensor based on a GO membrane attached with a Pt/C sensing electrode and a Pt black reference electrode showed good electromotive force (EMF) response to hydrogen in ppm concentrations in air at room temperature. The EMF changes were highly dependent on type of sensing materials and the Pt/C electrode gave high sensor responses in dry and wet conditions. Large EMF variations with changing H2 concentration were observed, indicating the promising capability of GO for on-line monitoring of hydrogen leakage.