bluuebunny/crossref_metadata_2025_split huggingface dataset:
PEM-Type Water Electrolysis/Fuel Cell Reversible Cell with Low PGM Catalyst Loadings
Authors: Ioroi Tsutomu , Yasuda Kazuaki 
Published: February 2020

To utilize fluctuating renewable energy stably and effectively, large-scale energy storage systems such as Li-ion, redox-flow and Na-S batteries have been extensively studied. Battery storage system have advantages of high efficiency in energy utilization and rapid response for energy demand, however initial system cost tend to be expensive. Electrochemical hydrogen production and storage is recently attracting attentions as another practical technology because of high energy efficiency of electrochemical water splitting, relatively low technological barrier for large-scale storage, and ease of long-term energy storage and long-range transport without self-discharge.
Regenerative fuel cell is an energy storage system using hydrogen as an energy medium. In particular, reversible (unitized) regenerative fuel cells (RFCs) can be functioned both as water electrolyzer and fuel cell in the same electrochemical cell by switching the operation mode, so that much more compact and cheaper system could be realized. In the PEM-type RFC, unsupported platinum/iridium-based catalysts are usually selected in terms of activity and stability for both operation modes. Loading amount of platinum group metals (PGMs) of RFC is relatively high (typically >1 mg cm-2) compared to the fuel cell dedicated system due to stability issue at high potentials during OER. Therefore, reducing PGM loadings without expense of performance and durability is high priority to meet the capital cost of the systems.
To reduce the PGM loadings of oxygen electrode of RFC, we examined electro-conductive Magneli phase titanium oxides (in particular Ti4O7) as a catalyst support material [1,2]. High surface area oxide support was prepared by UV laser technique; TiO2 nano particles dispersed in an appropriate solvent (typically acetonitrile) are reduced by pulsed UV laser irradiation [3]. Pt, Ir, and Pt-Ir alloy nano particles were deposited on the oxide support, and their electrocatalytic activities were examined by rotating disk electrode and MEA. Ti4O7-supported Pt catalyst showed 3 times larger electrochemical active area (ECA) than that of commercially available Pt black, and 2.9 and 2.4-fold mass activity was obtained for ORR@0.9V and OER@1.7V, respectively. Initial ORR/OER cycle durability test was conducted for Pt/Ti4O7 catalyst MEA at 80oC between >1.8V for OER and <0.8V for ORR, and almost no performance loss was observed. These results show titanium oxide based materials can be applied as RFC catalyst support, which leads to effective use and lowering PGM loading in the oxygen electrode.

References

1. G. Chen, S. Bare, T. Mallouk, J. Electrochem. Soc., 149, A1092 (2002).
2. T. Ioroi, T. Akita, M. Asahi, S. Yamazaki, Z. Siroma, N. Fujiwara, K. Yasuda, J. Power Sources, 223, 183 (2013).
3. T. Ioroi, H. Kageyama, T. Akita, K. Yasuda, Phys. Chem. Chem. Phys., 12, 7529 (2010).
Dual Nafion/Polyaniline Nanofibers Architecture for Applications in Fuel Cells Electrodes
Authors: Simotwo Silas , Kalra Vibha 
Published: February 2020

We demonstrate a facile route for fabrication of nanostructured fuel cell cathode catalyst support via simultaneous co-electrospinning of electron and proton conducting materials. Solutions of Nafion and polyaniline (PANI) were electrospun simultaneously from two separate nozzles on a common substrate with the aim to develop co-percolating electron and proton conducting pathways. Owing to the lack of entanglements in Nafion and PANI solutions, PEO was used to aid in electrospinning of both solutions. The composition of the dual nanofiber mat was tailored by varying the relative solution concentrations and flow rates. SEM micrographs (fig.1 (a)) of the mats show three-dimensional porous non-woven morphology, which is ideal for facile gas transport and also for enhancement of the triple phase surfaces. Electrochemical impedance spectroscopy show presence of independent charge transfer channels in the composite fiber mats (fig.1 (b)). Equivalent circuits were used to decouple electrical conductivity from protonic conductivity. Electrical conductivity was also verified via current/voltage (I-V) curves. Dual fiber mat with a Nafion/PANI/PEO composition of 50/32/18 showed proton conductivity of 0.032 S/cm and electron conductivity of 0.042 S/cm. Such proton conductivity was shown to be higher than the pure Nafion (with 2wt% PEO as the carrier polymer) nanofiber mat. The dual fiber mat also showed the highest water intake capacity (presumably due to its high composition of the hydrophilic PEO), which we believe is responsible for its higher proton conductivity. Such dual fiber mats with percolating phases of both electron and proton conductors and a three dimensional through–connected inter-fiber pore structure (for gas transport) can serve as an excellent catalyst support for PEMFCs.

Figure 1 Nanofiber mat with a Nafion/PANi/PEO weight composition of 50/32/18 (a): SEM micrograph, Scale bar; 1µm, b) Nyquist plot showing experimentally-obtained data and fitted impedance data obtained via an equivalent circuit.

Figure 1
Electrochemical Impedance Spectroscopy as a Diagnostic Tool for High-Temperature PEM Fuel Cells
Authors: Mack Florian , Laukenmann Ruben , Galbiati Samuele , Kerres Jochen A. , Zeis Roswitha 
Published: February 2020

The high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) continues to attract great interest as an alternative power source for stationary and auxiliary applications. The operating temperature of HT-PEMFCs ranging from 140 °C to 200 °C offers several advantages compared with low-temperature (<100 °C) PEMFCs such as higher tolerance to impurities like carbon monoxide (CO) and simplified water management. HT-PEMFCs based on phosphoric acid doped polybenzimidazole (PBI) membranes are so far the most promising candidates for practical high-temperature operation. For commercialization, however, the performance and long-term stability of the high-temperature membrane electrode assemblies (MEAs) still need significant improvement. To achieve this goal, suitable analytical tools to evaluate single cells and their components are critical for the MEA developers.
One such basic tool is electrochemical impedance spectroscopy (EIS). The technique is highly versatile, and instruments are widely available in electrochemistry laboratories. Here we present the capability of EIS to analyse the performance of high-temperature MEAs for optimizing their composition and material selection. We investigated MEAs with various commercial catalysts, PTFE contents, acid doping levels, and acid base blend membranes. Polarization curves and impedance spectra were taken for all these individual cases. Depending on the operating condition and the MEA design, up to three semi-circles were observed in the HT-PEMFC Nyquist plot, which allows us to resolve the individual cell overpotentials due to membrane resistivity, hydrogen oxidation, oxygen reduction, and mass transport. Such rich information acquired with EIS helps reveal the underlying processes occurring in the MEA during fuel cell operation, which is essential for MEA design and optimization.
Impact of Organic Cation Adsorption on the Hydrogen Oxidation Reaction of Pt in Alkaline Fuel Cells
Authors: Chung Hoon T , Martinez Ulises , Chlistunoff Jerzy , Kim Yu Seung , Choe Yoong-Kee , Matanovic Ivana 
Published: February 2020

Relatively poor hydrogen oxidation reaction (HOR) kinetics in alkaline membrane fuel cells compared with those in proton exchange membrane fuel cells can limit the cell performance [1]. In the previous work, we have compared the HOR kinetics of platinum electrocatalysts with two structurally different polymer electrolytes, i.e. benzyl trimethyl ammonium functionalized polyaromatic ionomer and phenyl tetramethyl guanidinium functionalized perfluorinated ionomer [2]. In this presentation, we will give further evidence on organic cation adsorption and their impact on HOR kinetics on Pt under high pH conditions. Direct observation of organic cation adsorption on the disk platinum electrode using surface enhanced FT-IR is closely related to the HOR activities. Computational calculations give further insight on cationic structural effect on adsorption kinetics. Mitigation strategy will be discussed in order to improve HOR kinetics of electrocatalysts in alkaline membrane fuel cells.

Acknowledgements

US department of Energy Fuel Cell Technologies Program (Program Manager: Nancy Garland) supports this research through Fuel Cell Incubator Project.

References

W.C. Sheng, H.A. Gasteiger, Y. Shao-Horn, “Hydrogen Oxidation and Evolution Reaction Kinetics on Platinum: Acid vs Alkaline Electrolytes,” J. Electrochem. Soc., 157, B1529 (2010).

Sung-Dae Yim, Hoon T. Chung, Jerzy Chlistunoff, Dae-Sik Kim, Cy Fujimoto, Tae-Hyun Yang, Yu Seung Kim, “A Microelectrode Study of Interfacial Reactions at the Platinum-Alkaline Polymer Interface,” J. Electrochem. Soc., 162, F499 (2015).
Effective Nickel and Ruthenium Modified Palladium Anode Catalysts for Ethylene Glycol Oxidation in Alkaline Medium
Authors: Da Silva Rodrigo Garcia , De Andrade Adalgisa Rodrigues , Servat Karine , Morais Claudia , Napporn Teko W. , Kokoh Kouakou Boniface 
Published: February 2020

As one of the attractive fuels in the direct alcohol fuel cell applications, the ethylene glycol electrooxidation was investigated in alkaline medium on Pd-based bimetallic catalysts (PdM/C, where M = Ni, Ru). These electrode materials were synthesized by polyol method, using ethylene glycol as both solvent and reducing agent. The resulted anode catalysts displayed effectiveness toward the oxidation of ethylene glycol. The latter molecule was also scrutinized as potential fuel which can be converted by cogeneration into energy (5.2 kWh kg-1) and particularly to added value product. Ex situ analytical measurements with liquid chromatography/Mass spectrometry provided evidences on the identification of glycolate as the main reaction product on the PdM/C anode materials (Figure 1).

Figure 1: Glycolate1 isolated and identified by LC-MS as the main compound issued from the ethylene glycol oxidation at the Pd-M/C (M = Ni and Ru) catalysts in alkaline medium.
The identification of some adsorbed intermediates and the final reaction products, was also supported by combining electrochemical (cyclic voltammetry, chronoamperometry) and in situ reflectance infrared spectroscopy experiments. The PdNi/C catalyst showed the highest intrinsic catalytic activity for the ethylene glycol oxidation. From FTIR experiments our findings gave evidences that the initial molecule skeleton was conserved and carbon monoxide was observed in a low amount.
Acknowledgements: Da Silva R.G. gratefully acknowledges FAPESP (2012/07464-0; 2013/25632-0) and CNPq for his fellowship.

L.M. da Palma, T.S. Almeida, V.L. Oliveira, G. Tremiliosi-Filho, E.R. Gonzalez, A.R. de Andrade, K. Servat, C. Morais, T.W. Napporn, K.B. Kokoh, RSC Adv., 4, 64476 (2014).

Figure 1
Inhibiting the Swelling Behavior of Nafion Membranes for PEM Water Electrolysis
Authors: Carmo Marcelo , Henkensmeier Dirk , Lüke Wiebke , Stolten Detlef 
Published: February 2020

Nafion is a commercially available perfluorosulphonate (PFSA) polymer electrolyte membrane (PEM) commonly used in both PEM fuel cells and electrolyzers. Catalyst coated membranes (CCMs) are prepared by hot-pressing the catalyst layers on a hot and dry Nafion film[1]. In the electrolyser, the dry CCMs get in contact with liquid water, which swells the membrane. Because the CCM is clamped in the cell, this leads to formation of folds and wrinkles. Furthermore, when the membrane shows stronger in-plane swelling than the catalyst layer, this swelling can also lead to membrane-electrode delamination and formation of electrode cracks. Therefore, the large in-plane swelling of Nafion membranes is an unwanted feature.
In this work, a facile and economical approach was developed to inhibit the in-plane swelling behavior of Nafion membranes. When first swollen on a fixed metal frame and afterwards dried in a fixed geometry, the Nafion film will memorize the wet shape and show reduced area swelling upon rehydration, providing outstanding benefits for CCM fabrication[2]. We expect that when using Nafion membranes with inhibited swelling behavior for CCM fabrication, the life time of PEM water electrolyzers shall be remarkably increased.
[1] M. Carmo, D. Fritz, J. Mergel and D. Stolten, International Journal of Hydrogen Energy, 38, 4901-4934 (2013)
[2] S. Hink, D. Henkensmeier, J. H. Jang, H.‐J. Kim, J. Han, S.‐W. Nam, Macromol. Chem. Phys. 2015, DOI: 10.1002/macp.201500063.
Investigation of Mass Transport Losses in Polymer Electrolyte Electrolysis Cells
Authors: Suermann Michel , Schmidt Thomas J. , Büchi Felix N 
Published: February 2020

Dynamically operable polymer electrolyte water electrolysis cells (PEEC) are also targeted at storing excess electric energy from renewable sources in hydrogen and oxygen in order to prevent curtailment [1].
In the energy storage application, efficiency of the processes is of particular concern not to waste precious renewable electricity. PEEC allow operation up to current densities around 5 A/cm2 and the losses increase accordingly. Similar as in fuel cells, different processes contribute to the voltage losses with increasing current. While the contribution of the ohmic overvoltage is well characterized and can easily determined by measuring the high frequency resistance of the cell [2], the catalytic and transport losses are more rarely investigated.
For determining the mass transport losses, also the catalytic losses need to be characterized, which needs careful analysis in particular when pressure varies over a wide range. The dependence of the transport losses is determined as function of the structures employed as current collectors, i.e. possible two phase phenomena in the porous structures as well as for different operating conditions with respect to pressure and temperature. The results show that over a wide range of current densities a quite significant part of the voltage losses can to be attributed to mass transport.
[1] C.J. Barnhart, et al., Energy Environ. Sci., 6, 2804-2810 (2013).
[2] C. Rozain, P. Millet, Electrochim. Acta, 131, 160-167 (2014)

Figure 1
Pt Electrocatalyst Supported on a 3D-Nanoporous Carbon Shows a High Performance in a High-Temperature Polymer Electrolyte Fuel Cell
Authors: Nakashima Naotoshi , Yang Zehui , Moriguchi Isamu 
Published: February 2020

Considerable attention has been focused on the high-temperature PEFCs (> 100 oC), due to their benefiting PEFCs with higher carbon monoxide (CO) tolerance, faster electrochemical kinetics, and better water management than those of conventional PEFCs. However, the high-temperature PEFCs also suffer from their low durability in terms of carbon corrosion and platinum nanoparticles (Pt-NPs) aggregation resulting in the detachment of the Pt-NPs from the catalysts and loss in electrochemical surface area (ECSA) as well as the degradation of FC performance. Thus, enhancement in durability is highly demanded for the commercialization of the next-generation PEFCs.
We have already reported that poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI) is an efficient dispersant for carbon supporting materials and provides the anchor sites for the Pt-nanoparticles (NPs) as well as creating the so-called three-phase boundary structure[1-7].
In this paper, we used a 3D nanoporous carbon (NanoPC) with a high specific surface area of 1,037 m2/g as a carbon support for high-temperature polymer electrolyte fuel cell, and fabricated an electrocatalyst (NanoPC/PyPBI/Pt) having platinum nanoparticles of ca. ~2.2 nm diameter deposited on the NanoPC that was wrapped by poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI). Even after 10,000 start-up/shutdown cycles in the range of 1.0 to 1.5 V vs. RHE, the NanoPC/PyPBI/Pt showed almost no loss in electrochemical surface area (ECSA), which was much higher durability than those of a CB/PyPBI/Pt (~32%-loss), in which conventional CB was used in place of the NanoPC, and conventional CB/Pt (~46%-loss).
FC performance of the assembled MEAs was evaluated at 120 ºC without any external humidification using a computer-controlled fuel cell test system. The polarization and the power density curves were measured under the atmospheric pressure by flowing dry hydrogen (flow rate; 100 mL/min) and dry air (flow rate; 200 mL/min) at the anode and the cathode, respectively.
The power density of the NanoPC/PyPBI/Pt was 342 mW/cm2, which was higher than those of the CB/PyPBI/Pt (183 mW/cm2) and CB/Pt (115 mW/cm2).
The present study provides useful information for the preparation of an electrocatalyst with a high durability and performance in high temperature PEFCs.
References
[1] N. Nakashima et al., Small
2009,
5, 735-740.
[2] N. Nakashima et al., J. Mater. Chem.
2011,
21, 1187-1190.
[3] N. Nakashima et al, Scientific Reports, 2013, 3, article no. 1764.
[4] N. Nakashima et al.,, ChemCatChem, 2014, 6, 567-571.
[5] N. Nakashima et al, Scientific Reports, 2014, 4, article no.6295.
[6] N. Nakashima et al., ChemPlusChem, 2014, 79, 400-405.
[7] Nakashima et al., N., J. Mater. Chem. A
2014,
2, 18875-18880.
Characterization of Liquid Water Invasion in Gdls Using X-Ray Tomographic Microscopy
Authors: Lamibrac Adrien , Roth Jörg , Eller Jens , Marone Federica , Büchi Felix N 
Published: February 2020

The accumulation of liquid water in the gas diffusion layer (GDL) of low temperature polymer electrolyte fuel cells (PEFC) results in increased mass transport limitations [1] and eventually in a significant potential and efficiency penalty. To achieve efficient water removal and maintain high performance, it is necessary to understand the morphological (porosity, pore and throat sizes) and chemical (surface tension) properties of the GDL, which control the water transport [2].
An ex-situ capillary pressure (pc) – saturation setup was developed in the framework of the IMPALA project [3] for imaging experiments using X-ray tomographic microscopy (XTM) at the Swiss Light Source synchrotron facility as it offers the advantage of well defined capillary pressure boundary conditions. This approach allows a quantitative analysis of the water transport through the GDL by linking the local saturation at the achieved pc levels with the microstructure of the invaded pores and throats.
Within the setup, a hydrophilic membrane implements a homogeneous boundary condition at the bottom of the GDL. At the top of the GDL either a hydrophobic membrane or a flow field was placed. While the hydrophobic membrane setup allows to study complete liquid wetting of the pore space, the flow field structure allows to implement an anisotropic compression simulating PEFC conditions and to study its consequences on water transport.
GDL samples of different suppliers have been tested. The breakthrough pressure, which corresponds to the capillary pressure when water reaches the opposite side of the injection surface, is a function of the materials. Correlation with the dry GDL microstructure shows that pore (and throat) size is the major controlling parameter. SGL 24BA shows a lower breakthrough pressure than Toray TGP-H060 due to larger throats and exhibits a stronger channel rib deviation of pore and throat sizes as well as of saturation.

References

[1] T. Rosen et al., Journal of the Electrochemical Society, 159 (2012) F536-F544.
[2] R. Flückiger et al., Electrochemica Acta, 56 (2011) 2254-2262.
[3] “IMprove Pemfc with Advanced water management and gas diffusion Layers for Automotive application” within the Fuel Cells and Hydrogen Joint Undertaking (FCHJU) initiative of the European Union. http://www.impala-project.eu

Figure 1: Capillary pressure saturation curves of Toray TGP-H060 and SGL 24 BA measured with the hydrophobic membrane setup (left) and the flow field setup (right). Compared to Toray TGP-H060 SGL 24BA shows a lower breakthrough pressure due to larger throats and exhibits a stronger channel rib deviation in saturation, as well as pore and throat sizes.

Figure 1
Novel Gas Diffusion Layers with Patterned Wettability
Authors: Forner-Cuenca Antoni , Biesdorf Johannes , Gubler Lorenz , Schmidt Thomas J. , Boillat Pierre 
Published: February 2020

Inside a polymer electrolyte fuel cell (PEFC), the water management is rather complex: on one hand, the membrane needs a certain hydration state in order to ensure a sufficient proton conductivity; on the other hand, excessive water leads to blocked gas pathways with increased mass transport losses. Liquid product water is transported by capillary forces [1] from the catalyst layer throughout the gas diffusion layer (GDL) towards the gas flow channels, in opposite direction of oxygen diffusion.
Under high current densities, the water production rate becomes high and the volume occupied by water can dramatically decrease the accessibility of oxygen resulting in mass transport limitations (so-called flooding). To address this issue, we are developing new GDLs with patterned wettability [2]. The idea is to define engineered hydrophilic pathways to force the transport of liquid water through them and vacate the rest of the volume for the transport of gases, decreasing the tortuosity.
The proposed synthetic method bears significant advantages compared to other reported approaches such us laser perforation [3] or local application of hydrophobic coating [4]: full flexibility in the pattern design without compromising the mechanical integrity, smaller hydrophilic regions can be defined (100 µm achieved) and the ratio between hydrophilicity and hydrophobicity can be tuned. Figure 1 shows the water preferentially accumulating in the hydrophilic regions.
In this talk, we will present details about the synthetic method together with ex-situ characterization results: chemical information based on energy dispersive x-ray (EDX) spectroscopy mapping (Figure 2) and water distribution with neutron radiography. Additionally, first operando results using the multicell setup [5] with pulsed gases analysis (PGA) will also be presented.
[1] U. Pasaogullari, et al., Int. J.Electrochem. Soc., 151 (2004), pp 399-406.
[2] P. Boillat, et al., European Patent Application EP15165515.6, (2015).
[3] D. Gerteisen, et al., J. Power Sources,177 (2008), pp 348-354.
[4] R. Koresawa, et al., J. Power Sources,271 (2014), pp 16-24.
[5] P. Oberholzer et al., Electrochem. Commun., 20 (2012), pp. 67-70.

Figure 1
Corrosion Resistant Electrospun Niobium Carbide Nanotube Supports for PEMFC Cathodes
Authors: Nabil-Moreau Yannick , Cavaliere Sara , Harkness Ian , Hards Graham , Sharman Jonathan , Jones Deborah Jacqueline , Rozière Jacques 
Published: February 2020

Recent research has shown that metal carbides and nitrides can potentially present the required properties to replace the carbon blacks conventionally used as electrocatalyst supports in Proton Exchange Membrane Fuel Cells (PEMFC). Our aim is to associate these alternative compositions with controlled morphologies to design electronically conductive and chemically stable materials with the appropriate porosity.
Currently we are developing a range of synthesis routes leading to NbC based materials with different morphologies leading to high surface areas. For example, using a three step synthesis, we prepared hollow microspheres of niobium carbide with a surface area of 70 m2
g-1 and an electronic conductivity of 103 S m-1. Furthermore we are developing various syntheses leading to electrospun niobium carbide nanofibres with different porosities in order to study the influence of the morphology on surface area and electrochemical activity.
These various supports have been catalysed by deposition of platinum nanoparticles synthesised by a microwave assisted polyol method, and they have been evaluated as electrocatalyst support for the oxygen reduction reaction.
This contribution will describe the preparation of Pt on NbC-based supports and their chemical and electrochemical characterisation including cyclic corrosion tests to evaluate their stability over time compared with Pt on carbon.