bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of New Biological Membranes for Their Possible Application in Electrolytic and FUEL CELLS at Low Temperature
Authors: Arredondo-Baeza Cristian Humberto , Hernandez Prisciliano , perez-Silva Irma , Aguilar-Lira Guadalupe Yoselin , Rodriguez Jose Antonio , Dominguez Julia Maria 
Published: February 2020

The present work describes the characterization of new protonic exchange biological membranes, using “maguey” as raw material, with the aim of providing a new alternative due to the fact that, over the past few years, Nafion (perfluorinated polymer) has been the most commonly utilized as polymer membrane in various application: Direct Alcohol Fuel Cell, Methanol and hydrogen [1], as well as electrolysers. In this sense, has been development different modifications to the Nafion [2] membrane without replacing it completely.
The organic membrane was based on the use of the “penca” cuticle. The cutine, the main component of the cuticle, is a polymer that consists of long chain fatty acids by ester-type bonds [3]. The epidermis of the plant is mainly responsible for gas exchanging through stomata which allows the cuticle to act as an interface between the cell and the external environment, thus allowing the proton exchange in the electrochemical process.
There were various types of treatments to the organic membranes, such as: mechanical activations, acidic, alkaline, polymeric coatings, electrical and thermal. With the purpose of obtaining hydrogen and oxygen in an electrolyzer. It was noted that the viable treatments for activation are both the mechanical and thermal, highlighting the thermal treatment as ideal due to the higher average life span and obtaining current intensity, in comparison with the mechanical treatment, which represents a lower average life span. In addition, the bio-membrane is coupling in a methanol fuel cell results competitive with commercial Nafion membrane, as shown in Table 1.
There were different techniques to know the morphology of the membrane, as well as their functional groups (SEM, Infrared, Raman), so the incorporation in an electrolytic cell and fuel show similar results to the Nafion membrane, which is a viable alternative to replace the Nafion.
References
[1] Ping Li, Wenjia Wu, Jindun Liu, Benbing Shi, Yaqian Du, Yifan Li, Jingtao Wang. Investigating the nanostructures and proton transfer properties of Nafion-Go hybrid membranes. Journal of Membrane Science. In Press, Accepted Manuscript, (2018) xxx.
[2] F. Ahmad Zakil, S.K. Kamarudin, S. Basri, Modified nafion membranes for direct alcohol fuel cells: An overview, renewable and Sustainable Energy Reviews 65 (2016) 841-852.
[3] Denise Castro-Ochoa, Carolina Peña-Montes y Amelia Farrés, Producción y características de cutinasas: Una alternativa interesante para biocatálisis a nivel industrial, TIP Revista Especializada en Ciencias Químico-Biológicas, 13 (2010) 16-25.

Figure 1
Impact of Co-Alloy Leaching and Cation in Ionomer Thin-Films
Authors: Tesfaye Meron , Kusoglu Ahmet 
Published: February 2020

Strong R&D progress and increased demand for hydrogen powered fuel-cell cars, is shifting Polymer Electrolyte Fuel Cells (PEFCs) to lower Platinum electrocatalyst loading and to Platinum-cobalt (Pt-Co) alloys that have demonstrated double the kinetic activity improvement [1]. Implementation of these catalysts can lower catalyst cost to $7/kW (from $18/kW of standard Pt/C catalyst), surpassing the automotive requirement target of $10/kW and expediting commercialization [2]. Key challenge in integrating Pt-Co alloy catalyst as well as other Pt-Metal alloyed catalysts into the electrode assembly of PEFC has been durability and stability in the highly acidic environment. Co-alloy dissolution, leaching, surface oxide over layer formation upon heating, hollowing and particle facet loss have been demonstrated for Pt-Metal alloys via short and long lifetime tests and imaging techniques [3]. Amplifying this detrimental impact is the contamination of the membrane and the ionomer thin-film in the catalyst layer distressing conductivity, water uptake, and even gas transport [4]. In this talk, the direct impact of co-alloy and cation contamination in thin ionomer films of thickness < 200 nm is investigated in an effort to illuminate the direct effect of cations on structure and performance. Different levels of neutralization and leaching is mimicked by varying cation concentration and different counter ion types (Co2+, Ni2+, Na+, Cs+), which can elucidate impact of strength of ionic crosslinking and interactions on the polymer film’s nano-structure and water uptake behavior, characterized by grazing-incidence X-ray scattering and ellipsometry, respectively. Significant impact of confinement on structure and property will also be explored as a function of ionomer thickness to understand the performance of ionomer thin-films employed in the electrode assembly.
Acknowledgement
This work made use of facilities at the Joint Center for Artificial Photosynthesis at Lawrence Berkeley National Laboratory. This work was funded in part by the National Science Foundation Graduate Fellowship and the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy (under Contract No. DE-AC02-05CH11231).
References
[1] H. A. Gasteiger et al. Appl. Catal. B Environ., vol. 56, no. 1–2 SPEC. ISS., pp. 9–35, 2005.
[2] M. F. Mathias et al. Electrochem. Soc. Interface, vol. 14, pp. 24–35, 2005.
[3] E. Antolini et al. J. Power Sources, vol. 160, pp. 957–968, 2006.
[4] J. H. Dumont et al. ECS Trans., vol. 80, no. 8, pp. 861–867, 2017.
Heteropoly Acid Functionalized Membranes for High Performance and Chemically Stable Fuel Cell Operation
Authors: Motz Andrew R , Kuo Mei-Chen , Bender Guido , Pivovar Bryan S. , Herring Andrew M. 
Published: February 2020

There is still a need for membranes that operate in proton exchange membrane (PEM) fuel cells at hotter and drier conditions than can be achieved with current materials, >100°C and <50%RH. One approach pursued by us and independently by Kunz and co-workers was the use of inorganic super acids, such as the heteropoly acids (HPAs). HPAs are a sub group of the large class of metal oxygen clusters known as polyoxometalates in which a central heteroatom is surrounded by a number of W or Mo oxygen octahedra. For proton conductivity it is desirable that a strong negative charge be delocalized across the whole anion so that the proton will be as dissociated as possible. This limits the choice of HPA to the spherical tungsten based Keggin anion with as light as possible a heteroatom. This limit is reached with Si as the P based HPA is known to decompose in the presence of peroxide and the electron deficient nature of B renders the spherical Keggin anion unstable. Many fundamental studies have been undertaken on solid state HPA systems. In addition the Si based HPA are known to decompose oxygenated radicals and so offer a path to the development of a PEM that is oxidatively stable under fuel cell operating conditions. These studies indicated that despite the original report in the early 80’s that HPA had the highest proton conductivity reported at that time, that when dry there proton conductivity was disappointingly low at moderate temperatures.
The key is to distribute the HPA on a perfluorinated polymer backbone in such a way that the natural tendency of the HPA to cluster and crystalize is suppressed. Using dehydroflourination chemistry we have learnt to functionalism PVDF type polymers with molecules that can act as anchor points for lacunary HPA, where a lacunary HPA has 1,2 or 3 tungsten oxygen clusters removed to give bonding points. After much research we now can produce these materials in large area thin film membranes. The base material outperforms the state of the art PEM under standard conditions and has the highest chemical stability of any PEM proposed to date. We are now varying the HPA structure to try and avoid the HPA clustering issue, these membranes are being sprayed on gas diffusion electrodes which act as the support to the tin films. This is allowing us to run these as fuel cells at higher temperatures to asses the potential of HPA functionalized membranes in these applications.
On the Mechanism Responsible for the Catalytic Activity of Platinum for Oxygen Reduction Reaction (ORR) and predicting a cost effective replacement for Pt toward ORR
Authors: Reda Mahmoud R. , Reda Ghazi 
Published: February 2020

Pt is required as a catalyst for both oxygen reduction reaction (ORR) and hydrogen evolution reaction(HOR) . This means that any type of fuel cell or a configuration to split water into hydrogen and oxygen require platinum as a catalyst. Currently, much of the cost of fuel cells arises from the need for precious metal catalysts – primarily Pt – to drive the necessary electrochemical reactions. For example, the cost of the Pt alone in a PEFC for a small 100 kW car is higher than the cost of an entire 100 kW gasoline engine. And there is another problem. During the course of the lifetime of a fuel cell, the Pt cathode suffers from oxidation, migration, loss of active surface area, and corrosion of the carbon support. Impurities, as well as methanol diffusing from the anode side of DMFCs, can also ‘poison’ the catalyst, reducing its activity and efficiency. So not only do fuel cells rely on a high-price commodity for their operation, they also require a high density of that expensive material. Understanding the mechanism responsible for such material is necessary to reduce the cost of fuel cells and water splitting configuration. It is well known that the crystal structure of platinum is an face centered cubic (FCC). In this case the lattice constants which influence the bandgap energy are equal a. In fact it may be that the bandgap energy is inversely proportional to the inverse of the a**(3) [1] Based on the idea that the lattice constant influence the bandgap and the fact that the bandgap energy is the energy required to move the bonded valence electrons to free conduction band which is the energy required to do the rate limiting step for the ORR or HER, a mechanism for the effect of platinum will be derived.
Reference
[1] R. Da1ven, Phys. Rev. B, 8,12 1973
[2]D. Bensaid , International Journal of Metals, 2014 (2014), Article ID 286393, 7 pages
Performance of Carbon-Supported Pt Nanoparticles Covered by Silica Layers with Low Ionomer in Polymer Electrolyte Fuel Cells
Authors: Ohnishi Tomohiro , So Magnus , Takenaka Sakae , Tsuge Yoshifumi , Inoue Gen 
Published: February 2020

Developed novel catalysts has been enhanced its activity and durability by researchers. There are some approaches to enhance Pt activity such as alloy, core-shell, and nanoframe and to improve durability by covered catalysts such as Silica, carbon, and organic compound. However, as for evaluation of catalyst, it is generally difficult to reflect half-cell results to membrane electrode assembly (MEA) one after screening of catalysts in electrolyte by half-cell method. There is morphology of catalyst layers (CLs) structure such as secondary porous, tortuosity, and porosity in addition to morphology of catalysts such as Pt specific surface, activity, and carbon support pore. Therefore, it is necessary to design CLs to bring out the performance without loss(1,2). The amount of ionomer around Pt/C is focused. It is also important factor influencing CLs structure. Although ionomers contribute the proton conduction, an excess of it prevents diffusion of oxygen to decrease porosity. Thus, decreasing ionomer amount is better in terms of oxygen diffusion. However, it is difficult to prepare the CLs loading low amount of ionomers by typical coating method since ionomers have a role in binding between secondary particles and increasing viscosity of ink. The catalyst by coverage Silica layer produced by Takenaka et al. is focused. Covering silica is one of the useful method to improve durability of Pt/C(3,4). The surface characteristics is transmuted by covering silica on the Pt/C. And then, it is available to keep the good dispersion ink even if low ionomer/carbon mass ratio (I/C). In this work, CLs with low I/C and effect of silica coating is evaluated by output performance using catalyst covered silica layer.
CLs was prepared using by inkjet method. I/C enable to be reduced down to 0.25 in standard sample (TEC10V50E, Tanaka kikinzoku kogyo). Below this value, it is difficult to prepare the CLs to agglomerate the secondary particles since ionomers is not enough as a binder. As for silica catalyst, it is available to reduce I/C down to 0.05 while ink keeps good dispersion. The dispersibility is enhanced by difference between surface characteristics. Low I/C samples were showed performance same as typical method of I/C = 1.0 in high humidity. It is possible to get the good performance with low I/C. In addition, output covered silica layer is better than standard sample in low humidity. The result indicates that silica plays a role in humectant-like.

Inoue and M. Kawase, J. Power Sources, 327(14), 1, (2016).

Kotoi, G. Inoue, and M. Kawase, ECS Trans., 75, 385, (2016).

Takenaka, H. Matsumori, K. Nakagawa, H. Matsune, E. Tanabe, and M. Kishida, J. Phys. Chem. C, 111(42), 15133, (2007).

Takenaka, H. Matsumori, T. Arike, H. Matsune, and M. Kishida, Top. Catal., 52(6-7), 731, (2009).
Molecular Dynamics Study of the Thickness Dependence of Structure and Mass Transport in Ionomer Thin Film
Authors: Kobayashi Koichi , Mabuchi Takuya , Inoue Gen , Tokumasu Takashi 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) are promising for automobiles and various applications because of their high power density and low operating temperature. The cost must be reduced without sacrificing performance of cells by decreasing Pt loading. However, at lower Pt loading, the efficiency decreases because mass transport losses largely increase at higher current density. Proton transport resistance is one of the causes of the losses. It is considered that proton transport property in ionomer thin films is improved with increasing the thickness of the films, whereas oxygen transport resistance increases with increasing the thickness. Ionomer thin films with high proton conductivity are required even though the thickness is thin. For this reason, we obtained the thickness dependence of proton transport property and structure property in ionomer thin films using a molecular dynamics method.
As the ionomer thin film, Nafion was employed. We constructed a system of the ionomer thin film on carbon surface. The contact angle of carbon surface was set at 90 degrees. To analyze the thickness dependence of proton transport property and structure property, the films with the thickness of 4-10 nm were made by changing the number of the Nafion chains. The analyses have carried out by changing water content to 3 and 14. To analyze a correlation between the dynamics and structural properties of Nafion thin films, dynamics properties were evaluated by self-diffusion coefficient obtained from mean square displacement of protons, and structural properties were evaluated by mass density distributions and maximum water cluster length. We found that at high water content, self-diffusion coefficient of protons has hardly changed by the change of ionomer thickness, whereas at low water content, diffusion coefficient has a peak when the ionomer thickness is around seven nm. At this surface wettability, water cluster connectivity was highest when the thickness is around seven nm, and liquid molecule was concentrated at near ionomer/carbon interface and near ionomer/gas interface in the case of low water content. However, in the case of high water content, water cluster connectivity has hardly changed by the change of thickness. We find the thickness dependence of water cluster connectivity. Self-diffusion coefficient increases with increasing maximum cluster length.

Acknowledgment

This research is supported by New Energy and Industrial Technology Development Organization (NEDO). We use Integrated Supercomputation System at Institute of Fluid Science. I appreciate all the support we received from everyone.
Advances in Ptni Nanowire Extended Thin Film Electrocatalysts
Authors: Alia Shaun M , Neyerlin K.C. , Hurst Katherine , Zack Jason W. , Mauger Scott A , McNeary William W , Weimer Alan , Medlin Will , Zaccarine Sarah , Ngo Chilan , Pylypenko Svitlana , Buechler Karen , Pivovar Bryan S. 
Published: February 2020

Fuel cells offer tremendous promise in pushing society towards a more sustainable energy system by enabling the production of renewable fuels with zero criteria pollutant emissions. One key barrier for such a future energy system for fuel cell adoption s the need for platinum group metals for catalysis and the quantities required for efficient performance. It has been a long-standing goal to continually increase performance and durability of electrochemical devices, and one promising approach has been the development and implementation of extended thin film electrocatalysts.1

Our team has extensively investigated extended surface catalysts as a novel platform for increased performance and durability at lower cost.2,3,4 This presentation will highlight the advances of our team in the synthesis and implementation of extended surface electrocatalysts with a focus on PtNi nanowires (NWs) produced by atomic layer deposition (ALD) . We have demonstrated the ability to obtain high performance PtNi NWs following ALD deposition by a series of steps that include annealing under reducing conditions and acid leaching. This results in high activity and surface area catalyst that have limited Ni remaining, thereby mitigating issues of potential Ni contamination when assembled into MEAs.
These catalysts have been incorporated into fuel cells investigating several different processing variables including catalyst loading, ionomer to catalyst ratio, and inclusion of carbon. Through optimization efforts, we have been able to achieve mass activities that surpass US Department of Energy targets for both performance and durability as demonstrated in Figure 1. These results have started to show the potential of extended surface electrocatalysts in cell testing. This presentation will discuss the factors that have allowed these performances to be achieved and future work to further advance both the inherent electrochemical properties of these catalysts and also the MEA performance of fuel cells based on these materials.
Figure 1. Polarization curves for PtNiNW based on initial cell performance and after 5,000 cycles of carbon corrosion testing.

Mark K. Debe∗, Alison K. Schmoeckel, George D. Vernstrom, Radoslav Atanasoski, Journal of Power Sources 161 (2006) 1002–1011.

Shaun Alia, Svitlana Pylypenko, Arrelaine Dameron, KC Neyerlin, Shyam Kocha, Bryan Pivovar, J. Electrochem. Soc. 2016 163(3): F296-F301.

Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, Shyam S. Kocha, and Bryan S. Pivovar, J. Electrochem. Soc. 2015 162(12): F1299-F1304.

Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, David A. Cullen, Shyam S. Kocha, Bryan S. Pivovar, ACS Catalysis, 4, 2680, 2014.

Figure 1
Durability of Long-Life Low Power Fuel Cells
Authors: Borup Rod L. , Stariha Sarah , Baker Andrew M. , Rockward Tommy , Langlois David A. , Wilson Mahlon S. , Rau Jon 
Published: February 2020

Fuel cells have the potential to provide very low uninterrupted power for long periods (several decades) of time. The specifications for these applications can vary tremendously from transportation fuel cells that are a large driving force behind fuel cell development. For these applications, the fuel and oxidant supply are often required to be stored for the entire lifetime of the application; these systems have higher inherent safety and overall higher system energy density than batteries for these prolonged operational times.
Many of the technical challenges are application dependent but can include:

Fuel/oxidant loss (due to membrane/plates/seals permeability)

Membrane degradation and thinning (due to high cell voltages)

Passive system water management

Operation in uncontrolled environments (including operation a large temperature range and unpredictable/uncontrollable ambient atmospheres)

Control of power transients (microwatt to watt power levels)

The primary degradation modes expected for these applications involve the electrode layer, loss of catalytic activity, membrane thinning, changing hydrophobicity of carbon materials (which impacts water management) and corrosion of metallic bipolar plates (including increasing contact resistance). Electrode degradation involving performance loss of the cathode catalyst layer includes catalyst particle agglomeration, catalyst support corrosion, losses of catalyst layer porosity and loss of catalyst layer proton conductivity due to ionomer degradation. Depending on the systems load requirements, potential cycles can be many millions of cycles over decades long continuous operation. To minimize catalyst degradation, we expect that a Pt-black electrode will be superior compare to the Pt supported on carbon electrodes that are the preferred for transportation applications. To examine the durability of these catalysts we are conducting Accelerated Stress Testing (ASTs); Figure 1 shows an on-going test of a Pt-black catalyst over 1.3 million cycles. The square wave cycling induces Pt dissolution and re-precipitation (Ostwald ripening) of the platinum thus decreases the catalyst surface area. From Figure 1, catalyst surface area loss appears to have reached 30-35% loss, but has not substantially increased after about 750,000 cycles.
To avoid large amounts of hydrogen loss due to membrane cross-over, we are exploring multiple layers of membrane to make a thick, mechanically reinforced and chemically stabilized membrane. A primary method to examine membrane degradation is to examine radical attack of the membrane at OCV conditions. Membrane thinning was measured at approximately 1.7 - 4.2 micron/year over a 2.4 year test with H2/air, at 25 C, which over a 20 year operational life extrapolates to34 - 83 micron. This suggests that a membrane of > 200 micron thick will be required for a 20 year operational life at low power levels.

Figure 1