bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of Pt/MWCNT Electrocatalyst during Startup and Shutdown Cycles: Voltage Degradation in PEM Fuel Cells
Authors: Hasché Frédéric , Aoun Nadia , Weber Philipp , Durst Julien , Kunz Ulrich , Turek Thomas , Gasteiger Hubert A. 
Published: February 2020

Proton exchange membrane fuel cells (PEMFC) are interesting candidates for automotive applications. Today’s challenge is to increase the mass activity from pure platinum of currently 0.12 A/mgPt to 0.44 A/mgPt at 0.9 V (iR-free) vs. RHE, and to enhance the durability with a high stability in startup/shutdown (SU/SD) procedures.[1-3]

During SU/SD cycles, the cathode voltage of a PEMFC can increase up to 1.5 V vs. RHE which accelerates the carbon corrosion drastically. These huge carbon corrosion rates lead to a complete loss of the electrode structure, and therefore to a dramatic loss of performance. In order to reduce carbon corrosion, the chemically more stable multi walled carbon nanotubes (MWCNTs) can be used as catalyst support. The higher stability in comparison to conventional catalyst material was already demonstrated in rotating disk electrode (RDE) experiments.[4] Here, the electrocatalyst was tested with two different cycling protocols, (I) 0.5 to 1.0 V vs. RHE (10.000 cycles, 50 mV/s) and (II) 0.5 to 1.5 V vs. RHE (2.000 cycles, 50 mV/s) in deaerated electrolyte (0.1 M HClO4) at room temperature.
In this contribution, we present our recent results regarding the stability of Pt/MWCNTs under real hydrogen-air front experiments in 50 cm2 single cell. During this test, the anode side is successively flushed with hydrogen or air while the cathode side is continuously purged with air.
N. A., U. K. and T. T. acknowledge efzn for financial support.
Literature
[1] Department of Energy - Multi Year Research and Development Plan (2011), Table 3.4.13 Technical Targets: Electrocatalysts for Transportation Applications.
[2] Oezaslan, M.; Hasché, F.; Strasser, P., The Journal of Physical Chemistry Letters 2013, 4 (19), 3273-3291.
[3] Yu, P. T.; Gu, W.; Makharia, R.; Wagner, F. T.; Gasteiger, H. A., ECS Transactions 2006, 3 (1), 797-809.
[4] Hasché, F.; Oezaslan, M.; Strasser, P., Physical Chemistry Chemical Physics 2010, 12 (46), 15251-15258.
Effect of Au and Ru in Au@Pd and Ru@Pd Core@Shell Nanoparticles for Direct Formic Acid Fuel Cells
Authors: Hu Shuozhen , Scudiero Louis , Ha Su 
Published: February 2020

The study of Pd-based core@shell bimetallic catalysts with Pd as the shell and another transition metal as the core has generated great interest in the field of PEM fuel cells because their electronic and chemical properties are completely different from pure Pd. As the anode catalyst in direct formic acid fuel cells (DFAFCs), an enhanced activity has been obtained for these Pd-based core@shell nanoparticles compare to pure Pd for formic acid oxidation [1,2]. However, there is a lack of understanding of how these added transition metals interact with Pd, namely by influencing their electronic structure and chemical property toward electrochemical oxidation of formic acid. It is important to fill this knowledge gap and find out a trend between the effect of the transition metals and the activity. This will help developing more efficient and less cost DFAFCs.
In this study, Au@Pd and Ru@Pd core@shell nanoparticles with same thickness of Pd are synthesized via a two-step process. Non-supported nanoparticles are used for TEM and X-ray photoelectron spectroscopy (XPS) analysis. TEM is used to characterize the structure and morphology of the nanoparticles. XPS is used to differentiate the chemical shifts due to charge transfer between Pd and Au (or Ru). XPS analysis shows a different binding energy shift for Pd peak of Au@Pd and Ru@Pd compare to that of pure Pd nanoparticles. In addition, a change of the XPS valence band shape and down-shift of the d-band center are also observed. This different binding energy shift indicates that Au and Ru core interact with Pd shell and significantly influence the electronic structure of Pd. Electrochemical measurements (cyclic voltammetry and chronoamperometry) are used to investigate the electrochemical activity of carbon supported Au@Pd and Ru@Pd core@shell nanoparticles toward formic acid oxidation. The Pd loading of the carbon supported samples is 40wt%. Based on CV results shown in Figure 1, Au@Pd shows the best activity toward formic acid oxidation, which is about twice higher than that of Pd/C. The relationship between the electronic perturbation and electrochemical activity will be elucidated in this paper. Furthermore, a real direct formic acid fuel cell test will be also operated with these Au@Pd and Ru@Pd core@shell nanoparticles under the various fuel cell operating conditions.
References
1. Zhang, M. M., Yan, Z. X., Xie, J. M., Electrochimica Acta, 2012,
77: p. 237-243.
2. Li, Y. J., Wang, Z. W., Chiu, C. Y., Ruan, L. Y., Yang, W. B., Yang, Y., Palmer, R. E., Huang, Y., Nanoscale 2012,4 (3): p. 845-851.
Figure 1: Cyclic voltammetry measurements for carbon supported Au@Pd, Ru@Pd, and Pd nanoparticles in 0.5 M formic acid with 0.5 M H2SO4. Scan rate 20 mV/s.
Development of Ir Nanocatalysts As CO2-Tolerant Anodes in Electrochemical Hydrogen Pumps for H2/CO2 Separation
Authors: Kim Soo Jin , Lee Byung-Seok , Park Hee-Young , Jung Young-Hoon , Choi Insoo , Cho Eun Ae , Kim Hyoung-Juhn , Henkensmeier Dirk , Nam Suk Woo , Kim Sung Hyun , Yoo Sung Jong , Jang Jong Hyun 
Published: February 2020

Recently, various CO2 capture and storage (CCS) technologies have been actively researched and developed. As CO2 sources usually produce mixtures that contain other gases such as H2 and H2O, gas separation technologies are required to increase the efficiency of CCS processes, and the electrochemical hydrogen pump is expected to be effectively utilized for H2/CO2gas separation. Electrochemical hydrogen pumps will be suitable for the treatment of gas mixtures produced from coal gasification and steam-reforming processes, as well as the anode outlet gases from molten carbonate fuel cells integrated with fossil fuel power plants.
As electrocatalysts for electrochemical hydrogen pumps, carbon-supported Pt nanoparticles have been widely used for hydrogen compression [1] and hydrogen separation from gas mixtures [2, 3]. However, as Pt surfaces can be severely poisoned by the strong adsorption of CO molecules that are generated through the reverse water-gas shift reaction of CO2 and adsorbed hydrogen [4], the Pt catalyst in the anodes can be largely deactivated when H2/CO2gas mixtures are supplied to electrochemical hydrogen pumps.
In this study, we synthesized Ir-based nanocatalysts for the application of hydrogen separation from CO2-rich mixture gas and characterized them by XRD, XPS, TEM, and TGA. The electrochemical characteristics of Ir-based nanocatalysts were investigated by half-cell and single-cell tests, focusing on poisoning under CO2 atmosphere. The Ir-based catalyst demonstrated higher HOR/HER activity than the commercial Pt catalyst, and, by CO2 stripping analysis, it was confirmed that the CO poisoning under CO2 atmosphere was much smaller for Ir-based catalysts. As a result, enhanced hydrogen pump performances could be achieved with the anode feed of H2/CO2mixture.
References
[1] K. Onda, K. Ichihara, M. Nagahama, Y. Minamoto, T. Araki, J. Power Sources, 164, 1 (2007).
[2] B. Ibeh, C. Gardner, M. Ternan, Int. J. Hydrogen Energy, 32, 908 (2007).
[3] C.L. Gardner, M. Ternan, J. Power Sources, 835, 171 (2007) -841.
[4] N. Hoshi, T. Izuwra, Y. Hore, Electrochim. Acta, 40, 883 (1995) -887.
A Nonhumidified Fuel Cell Using Fluorohydrogenate Ionic Liquid - Polymer Composite Membrane: Advantages of the Use of Polyimide Membrane Supporting Material
Authors: Kiatkittikul Pisit , Nohira Toshiyuki , Hagiwara Rika 
Published: February 2020

Operation at intermediate temperature (> 100 °C) without humidification offers several benefits for PEFCs such as reduction of expensive noble catalyst and simplicity of the unit. In the previous study, we reported a non-humidified fuel cell using a composite membrane of C2C1pyrr(FH)1.7F (C2C1pyrr = N-ethyl-N-methylpyrrolidinium) ionic liquid and HEMA (2-hydroxyethylmethacrylate) polymer with polytetrafluoroethylene (PTFE) as a membrane supporting material [1]. However, the single cell performance largely decreased when the operation temperature was elevated from 80 °C to 120 °C. The reason for this deterioration was revealed by the cross-sectional SEM images of the membrane electrode assemblies, showing that the composite membrane was softened and the composite electrolyte penetrated into gas diffusion electrodes (GDEs) to partially plug the gas channels in the gas diffusion layer.
In this study, to improve the mechanical properties of the membrane at elevated temperature, polyimide (PI) was used as a membrane supporting material instead of PTFE due to its higher mechanical strength and thermal deformation temperature. C2C1pyrr(FH)1.7F and HEMA monomer were mixed in the molar ratio of 8:2 and 9:1. Small amount of AIBN (2,2'-Azobis(isobutyronitrile)) was added as a radical initiator. PI (thickness: 16 and 30 μm, I.S.T) used as a porous supporting material was immersed in the mixed solution under vacuum for 1 h. Then, polymerization was conducted at 70 °C in Ar-filled oven for 12 h. Single cell tests were conducted under nonhumidified conditions at 25-120 °C. The GDEs with 1.0 mg Pt cm-2 were used for both the anode and cathode.
Fig. 1 shows i-V and i-p curves for a single cell using C2C1pyrr(FH)1.7F-HEMA (8:2) composite membrane with 16 μm PI supporting material operated at 25-120 °C under nonhumidified conditions. Contrary to the previous result in which PTFE was used as a supporting material, the single cell performance increases with the elevation of temperature. The maximum power density of 35 mW cm-
2 is observed at 120 °C. Fig. 2 shows cross-sectional SEM images of the membrane electrode assembly (MEA) for a single cell using C2C1pyrr(FH)1.7F-HEMA (8:2) composite membrane with 16 μm PI supporting material; (a) before single cell test, and (b) after single cell test at 25-120 °C. Yellow arrow indicates the membrane thickness. Comparing (a) with (b), there is no significant difference on membrane thickness, which means the previous problem of the penetration of composite electrolyte into the gas diffusion layer has been solved. Thus, the deterioration of cell performance does not occur even at over 80 °C.

Reference:

[1] P. Kiatkittikul, T. Nohira, R. Hagiwara, J. Power Sources, 2012, 220, 10.

Acknowledgment: PI membrane supporting materials were provided from I.S.T Corporation.
Effect of Nanostructure of the Electrocatalyst Based on Carbon Nanotube for the Activation Overpotential for PEFC
Authors: Nagashima Akiyo , Fujigaya Tsuyohiko , Nakashima Naotoshi 
Published: February 2020

Polymer electrolyte fuel cells (PEFC) are considered as one of the promising power sources for automobile and house in near future due to their high energy conversion efficiency and compactness. Recently high temperature PEFC using the polymer membrane doped with liquid phosphoric acid (PA) is attracting strong interest since it shows higher power density, CO poisoning on platinum (Pt) can be avoided and no cooling and humidifying devices are required. However, it was pointed the high temperature PEFC has poor durability due to leaching of PA from the membrane, which causes the deterioration of PEFC performance during long-term operation[1]. To overcome this issue, poly(vinylphosphonic acid) (PVPA) was used as the electrolyte instead of PA. We found the membrane doped with PVPA was free from the leaching of the electrolyte since PVPA is polymer and solid acid. Although this PEFC showed high durability, this catalyst had large overpotential in the area of low current density, probably because the poisoning of Pt by PVPA coating[2] or the lack of electrolyte in catalyst layers[3]. In this study, first we explored the new preparation method to avoid the Pt poisoning and investigated the catalytic performance by electrochemical techniques. And then, we increased the amount of acid in the electrolyte and compared the overpotential.

[1] M. Hori et al. J. Power Sources
2012, 210, 366.
[2] C. Roth et al. J. Phys. Chem. C
2013, 117, 6210.
[3] J.H. Jang et al. Int. J. Hyd. E.
2010, 35, 2119.
Comparison of Borohydride Oxidation on the Gold Crystallites Deposited on the Smooth and Fiber Cobalt Coatings
Authors: Tamasauskaite-Tamasiunaite Loreta , Lichusina Svetlana , Balciunaite Aldona , Simkunaite Dijana , Zabielaite Ausrine , Selskis Algirdas , Juskenas Remigijus , Norkus Eugenijus 
Published: February 2020

In the present study the Co sublayers with different structures were used for the deposition of Au crystallites (denoted as Au(Co)/Ti). The smooth Co layer was deposited on the titanium surface via electroless deposition [1]. Cobalt coatings with a fiber structure were deposited from the electrolyte described in Ref. [2]. Au crystallites were deposited on the Co/Ti surface by immersion of Co/Ti into the 1 mM HAuCl4 + 0.1 M HCl solution at 25 oC for 0.5, 1 and 5 min, respectively [3].
The morphology, structure and composition of the prepared catalysts were examined by means of Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy. Electrocatalytic activity of the prepared catalysts was investigated towards the oxidation of borohydride by means of cyclic voltammetry and chronoamperometry.
It was found that the gold particles deposited on the cobalt with a fiber and smooth structures show enhanced electrocatalytic activity towards the oxidation of borohydride in an alkaline medium as compared to that of bare Au and Co deposited on the Ti surface with smooth and fiber structures.

References

[1] A. Vaskelis, A. Jagminiene, I. Stankeviciene, E. Norkus. “Electroless deposition of cobalt alloys”. US patent 7,794,530 B2 (2010).
[2] E. Juzeliunas, S. Lichusina. Patent of the Republic of Lithuania No. 5481 26.03.2008.
[3] L. Tamasauskaitë-Tamasiunaite, A. Jagminiene, A. Balciunaite, A. Zabielaite, J. Vaiciuniene, A. Selskis, R. Juskenas, E. Norkus. Int. J. Hydrogen Energy 38 (2013) 14232-14241.
Nuclear Magnetic Resonance Methods for Investigation of Electrochemical Phenomena in Direct Alcohol Fuel Cells
Authors: HAN Oc Hee 
Published: February 2020

Nuclear magnetic resonance (NMR) spectroscopy has been one of the essential methods to identify chemicals and characterize dynamics and structure of them. Utilizing the advantages of NMR spectroscopy we have investigated electrochemical phenomena occurring in direct alcohol fuel cells (DAFCs) and identified electronic, chemical and structural changes of FC components during each FC assembly and operation process. With the device that we have developed, the functional difference of anode catalysts such as Pt and PtRu could be in situ detected. Liquid state 13C NMR spectroscopy was utilized to analyze the anode exhaust of DAFC and to correlate quantitatively the amount of electrical current generated to the quantities of each chemical product. Magic angle spinning (MAS) NMR spectroscopy and the membrane electrode assembly (MEA) composed of triple-polymer electrolyte membrane layers were employed for the study of methanol crossover and methanol reaction intermediates in a DAFC.
Our work demonstrates that 1) in situ NMR observation of real DAFCs is possible, 2) the in situ and ex situ NMR techniques can be used for the investigation of alcohol oxidation reaction mechanisms, and 3) the electronic, chemical and structural changes of FC components during each FC assembly and operation process can be studied by various NMR methods.
Development of Electrodeposited IrO2 Electrodes and Its Catalytic Activity towards Oxygen Evolution Reaction in Polymer Electrolyte Membrane Based Water Electrolysis
Authors: Lee Byung-Seok , Ahn Snag Hyun , Choi Insoo , Park Hee-Young , Kim Soo-Kil , Lee Kwan-Young , Yoo Sung Jong , Cho EunAe , Kim Hyoung-Juhn , Nam Suk Woo , Jang Jong Hyun 
Published: February 2020

Polymer electrolyte membrane based water electrolysis (PEMWE) is an environmental friendly way to produce hydrogen with largely reduced CO2 emission [1]. However, for commercial applications, further cost reduction is highly required. Conventionally, Ir and Ru based electrocatalysts are utilized in anodes (~4 mg/cm2), and Pt based electrocatalysts in cathodes (~1 mg/cm2). In this study, electrodes were fabricated by anodic electrodeposition of IrO2on carbon papers [2], and its catalytic activities towards oxygen evolution electrodes (anodes) were characterized.
By anodic electrodeposition technique, IrO2 was electrodeposited on carbon papers in a three electrode cell (Autolab, PGSTAT302N). A glassy carbon electrode and SCE were utilized as counter and reference electrodes, respectively. The deposition voltage and time were varied to control the loading amount and surface morphology. After electrodepositon, the microstructures and oxidation states of IrO2 deposition were analyzed by field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The amount of deposited IrO2, which was determined by the inductively coupled plasma-mass spectrometry (ICP-MS), was 0.007~0.464 mg/cm2
at various deposition voltages and times.
For single cell tests, cathode electrodes were fabricated by spraying commercial Pt/C (Tanaka, 45.9 wt%) on carbon paper (Pt loading: 0.8 mg/cm2), and commercial Nafion 212 membranes were utilized as polymer electrolytes. Then, the water electrolysis performances were evaluated at 90oC. The highest performance was observed for the electrodes with IrO2 loading of 0.09 mg/cm2. Interestingly, although the anode catalyst loading was largely decreased, the single cell performances in this study were comparable to the previous reports [3-5].
References
[1] F. Mueller-Langer, E. Tzimas, M. Kaltschmitt, S. Peteves, Int
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Hydrogen Energy, 32, 3797, (2007).
[2] K. Yamanaka, Jpn. J. Appl. Phys.
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28, 632, (1989).
[3] Shidong Song, Huamin Zhang, Xiaoping Ma, Zhigang Shao, Richard T. Baker, Baolian Yi, Int.
J
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Hydrogen Energy, 33, 4955, (2008).
[4] Jinbin Cheng, Huamin Zhang, Guobao Chena, Yining Zhanga,
Electrochim
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Acta, 54, 6250, (2009).
[5] Lirong Ma, Sheng Sui, Yuchun Zhai, Int.
J
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Hydrogen Energy, 34, 678, (2009).
Novel Oxygen Evolution Catalysts for Proton Exchange Membrane Water Electrolysis
Authors: Rasimick Brian , Stocks Allison , Xu Hui 
Published: February 2020

Hydrogen production from proton exchange membrane (PEM) water electrolysis is attractive due to its simple and clean nature. However, the technology is expensive due to high materials cost for the catalysts, membrane, and bipolar plate. In most commercial processes, iridium (Ir) black is used as an oxygen evolution catalyst at the anode. A high Ir loading (>2mg/cm2) has to be used due to significant anode over-potential loss caused by sluggish kinetics of the oxygen evolution reaction.
The objective of this work is to develop advanced Ir catalysts with enhanced catalytic activity that may lead to decreased Ir loading and/or increased energy efficiency. Two categories of catalysts are being investigated. One is iridium nanotube catalyst, which is synthesized via a porous alumina template.1 The template can be a commercially available anodized alumina membrane with a relatively uniform capillary pore structure. The template was coated with an iridium precursor by subliming iridium precursor at an appropriate temperature. The precursor was then reduced to iridium. The template support was removed by etching with 10% potassium hydroxide. A cross-section of the nanotubes produced by this process is shown in Figure 1. The average length of the Ir nanotubes is 5um and the diameter ranges from 250 – 400 nm with a wall thickness of ≤50 nm. Energy-dispersive X-rayanalysis suggests that the tubes are composed of iridium dioxide. The template pore size and process conditions are being varied to change the dimension of the Ir nanotubes.
In addition to Ir nanotubes, Ir catalysts dispersed on a variety of corrosion-resistant substrates like titanium oxide and indium tin oxide (ITO) are also being developed. The Ir dispersion on these supports may reduce Ir particle size thus potentially enhancing its catalytic activity. Figure 2 shows the TEM image of Ir particles supported on TiO2nanowires with 30 w.t. % Ir loading.
The RDE performance and the electrolyzer performance of these catalysts are being investigated and their comparison with commercial Ir black will be reported.

Acknowledgement:The financial support is from the Department of Energy under the Contract Grant DE- DE-SC0007471. TEM was performed by Drs. Fan Gao and Zhiyong Gu at University of Massachusetts at Lowell.

References

Pivovar AB, et al. J Electrochem Soc, 160, F848-52 (2013).
Theoretical Study of the Morphologic and Structural Characteristics of an Anion Exchange Membrane Used in AEMFC Using DFT
Authors: Castañeda Ramírez Sergio , Ribadeneira Paz Rafael Esteban 
Published: February 2020

Anion-exchange membrane fuel cells (AEMFC) have great potential of commercialization at low cost for their use in automotive transportation, portable batteries and power generators with respect to similar technologies as the proton-exchange membrane fuel cells (PEMFC) due to: a) better kinetic characteristics both for the oxygen reduction reaction as for the hydrocarbon oxidation reducing costs of catalysts, b) lower fuel crossover from anode to the rest of the device, c) simpler water management and d) reduced degree of corrosion.
Despite the mentioned advantages, the polymeric materials used as electrolytes show low conductivity and chemical stability values, which limit respectively the efficiency and durability of the fuel cell, and as experimentally these factors have not been optimized yet, it is important to understand the related physicochemical phenomena, being the anion transport primordial. However, the characteristics of the mechanisms associated with that process are not well known particularly the Grotthuss mechanism, which is considered to contribute mostly to the hydroxyl ion mobility.
In order to understand the mentioned mechanism and to improve the description of the ion mobility in AEMFCs is mandatory to carry out a rigorous theoretical study, for which the first step is to describe the appropriate structure of a particular anion exchange membrane. So, the aim of the present research is study the morphological and structural characteristics of the quaternized polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene homogeneous membrane synthetized by Qing Hua Zeng and co-workers for different humidification values by means of density functional theory (DFT) techniques, considered the most suitable in terms of prediction and accuracy since there are not almost theoretical studies about structural and morphological characteristics of anion exchange materials used in AEMFC.
With the results obtained, the idea is to evaluate the potentiality of DFT techniques to obtain accurate structures for polymeric membranes and use the one generated for future investigations about the physicochemical characteristics of the Grotthuss mechanism for hydroxyl ions in membranes used in AEMFCs, in order to determine the best morphological and structural characteristics of this type of materials from a theoretical approach.