bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Role of Imaging in Modeling of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells
Authors: Fuller Thomas F. 
Published: February 2020

The predominate model of electrodes used for proton exchange membrane fuel cells (PEMFCs) is based on the macrohomogeneous porous electrode formulation. As valuable as this formulation is it cannot explain important phenomena that are present. A key example is the effect of low loadings of catalyst on the cathode. Experimentally, a reduction in the mass-transfer limiting current is observed, but the model predicts no effect. Additionally, the dynamics of liquid water in the catalyst layer are believed to be important, but predicting water transport even under steady-state conditions is challenging.
The development of tomographic and 3D imaging techniques, such as focused ion beam scanning electron microscopy, FIB/SEM, offers new opportunities in modeling of electrode. The challenges are twofold. First, obtaining an accurate reconstruction of the electrode structure is still difficult. Our efforts to measure these structures using FIB/SEM is described for samples subjected to accelerated stress testing designed to probe carbon loss are described.[i] The second challenge is simulation using these structures. Two routes for modeling are explored. The primary is direct simulation using the detailed, measured geometry. This direction is computationally expensive, but more and more it becoming viable. The alternate route also uses the actual geometry, relying on mathematically exact and statistically significant definitions of geometric tortuosity and geometric constrictivity, but seeks efficient means to find effective transport properties.
[i] Star, A. G. & Fuller, T. F. FIB-SEM Tomography Connects Microstructure to Corrosion-Induced Performance Loss in PEMFC Cathodes. J Electrochem Soc
164, F901-F907 (2017)
3D Analysis of Observed and Simulated Microstructure Evolution in SOFC Anodes
Authors: Wieler Matthias , Wankmüller Florian , Weber André , Hoffrogge Paul Wilhelm , Schneider Daniel , Nestler Britta , Haremski Patricia , Lupetin Piero 
Published: February 2020

An important degradation mechanism in solid oxide fuel cells (SOFCs) is the microstructural evolution of Ni-YSZ anodes caused by diffusional transport of nickel under operating conditions. In this work, we carry out 3D analysis on several data sets from FIB-SEM reconstructions of a full-ceramic co-sintered SOFC as well as from large-scale phase-field simulations, in order to obtain a quantitative understanding of the different microstructure evolution effects and their impact on anode degradation.
The experimental data stem from FIB-SEM reconstructions of both newly fabricated anodes and anodes aged for ca. 1000h under operating conditions. The simulated data stem from large-scale phase field simulations that have been initialized with a reconstructed microstructure. The underlying phase-field model incorporates both volume diffusion of nickel and interface diffusion along the Ni surfaces, grain boundaries, and Ni-YSZ interfaces. The required material parameters (interface energies and diffusivities) are determined partly by ab-initio simulations and partly by thermal grooving experiments on bicrystalline and polycrystalline nickel.
For the 3D analysis, we calculate standard microstructural features such as volume fractions, active and inactive three-phase-boundary (3PB) length, and tortuosity, and we use the transmission line model to calculate the expected anode performance. Comparison with the measured anode performance shows that the observed decrease of 3PB length explains the measured degradation only partly, while the main degradation factor is loss of connectivity of the nickel phase. To understand the connectivity loss in more detail, we carry out a bottleneck analysis to quantify the gradual tightening of the bottlenecks. In addition, we statistically assess the spatial homogeneity, and we calculate several shape descriptors such as interface areas and local structure size, which allows us to show that nickel relocates over considerable distances from small pores to larger pores within the YSZ skeleton.
(Invited) What’s Killing My Fuel Cell? a Retrospective on Polymer Fuel Cell Poisoning and Degradation Research
Authors: Garzon Fernando H , Mukundan Rangachary , Borup Rod L. 
Published: February 2020

PEMFCs are subject to many mechanisms that abruptly decrease power output or slowly degrade long-term performance. Los Alamos National Laboratory researchers pioneered many experimental investigations and forensic characterization studies to explore these effects. These include catalyst degradation, membrane performance loss and failure, gas diffusion layer degradation, and fuel and air poisoning mechanisms. This retrospective highlights a 25+ year effort at understanding and mitigating these effects.
In the early 1990s fuel cell performance loss was observed in fuel cells which by today’s standards, had relatively high catalyst loading and utilized thick Nafion 117 membranes [1]. Carbon monoxide was already well known to poison the hydrogen oxidation reaction. The processes of Pt coarsening, Pt-M, dealloying, carbon corrosion, membrane free radical attack, foreign ion-proton exchange, ammonia and sulfurous gas poisoning, were investigated in subsequent years. Many characterization techniques, in addition to voltammetry, were employed to study these processes including: XRD, SEM, EDS, TEM, XPS, XRF, X-ray microscopy & tomography, neutron imaging and ion and gas chromatography [2]. Modeling methods from atomistic calculations to macroscopic effective medium transport models were developed to further provide insights towards mechanisms and mitigation strategies. The efforts continue today as ultralow loading platinum group metal catalysts and alloys, PGM free electrocatalysts, supports and novel membranes are being evaluated for next generation fuel cells.
References

Wilson, M. S.; Garzon, F. H.; Sickafus, K. E.; Gottesfeld, S., Surface area loss of supported platinum in polymer electrolyte fuel cells. Journal of The Electrochemical Society
1993,
140(10), 2872-2877.

Borup, R.; Meyers, J.; Pivovar, B.; Kim, Y. S.; Mukundan, R.; Garland, N.; Myers, D.; Wilson, M.; Garzon, F.; Wood, D., et.al, Scientific aspects of polymer electrolyte fuel cell durability and degradation. Chemical reviews
2007,
107(10), 3904-3951.
(Invited) Electrocatalysis from First-Principles: Reaction Mechanisms and Ideas for Improved Materials
Authors: Mavrikakis Manos , Elnabawy Ahmed O. , Herron Jeff A. 
Published: February 2020

Density Functional Theory (DFT) has enabled the search for improved electrocatalysis, based on DFT-identified reactivity descriptors for a wide variety of reactions and surfaces1, 2. Concurrently, the inorganic synthesis community has achieved important successes towards the robust synthesis of shape-selected nanocrystals which preferentially expose certain facets and morphologies3, 4. We start this presentation by discussing our work on the structure sensitivity of ammonia electrooxidation on transition metals in alkaline fuel cells; the kind of fuel cells that Dr. S. Gottesfeld has passionately investigated for many years5. We explain the higher activity of Pt(100) versus Pt(111), and propose the binding energy of atomic nitrogen as a key reactivity descriptor for this environmentally-benign electrochemistry6. We will then present some of our work on acidic fuel cells, especially regarding the electrooxidation of formic acid on transition metals7, and, with time permitting, on Pt and Pd monolayers on transition metals. Unlike ammonia electrooxidation, we here propose two reactivity descriptors (the free energy of adsorbed CO* and the free energy of adsorbed OH*) to adequately describe the search space for improved catalysts for formic acid electrooxidation.
[1] T. Bligaard, J. K. Nørskov Electrochim. Acta. 2007, 52, 5512-5516.
[2] J. K. Nørskov, F. Abild-Pedersen, F. Studt, T. Bligaard Proc. Natl. Acad. Sci. U.S.A.
2011, 108, 937-943.
[3] A. Ruditskiy, S.-I. Choi, H.-C. Peng, Y. Xia MRS Bull.
2014, 39, 727-737.
[4] A. Ruditskiy, H. C. Peng, Y. N. Xia Ann. Rev. Chem. Biomol. Eng. Vol 7. 2016, 7, 327-348.
[5] S. Gottesfeld, D. R. Dekel, M. Page, C. Bae, Y. S. Yan, P. Zelenay, Y. S. Kim J. Power Sources. 2018, 375, 170-184.
[6] J. A. Herron, P. Ferrin, M. Mavrikakis J. Phys. Chem. C. 2015, 119, 14692-14701.
[7] A. O. Elnabawy, J. A. Herron, J. Scaranto, M. Mavrikakis J. Electrochem. Soc. 2018, 165, J3109-J3121.
(Invited) Low Temperature Electrolysis for Hydrogen at Scale
Authors: Mukerjee Sanjeev , Kendrick Ian , Doan Huong 
Published: February 2020

This presentation will focus on durable, high-performance materials and interfaces for advanced water splitting, enabling a clear pathway for achieving <$2/KgH2 (on scale) with efficiency of 43 KWh/Kg using anion exchange membrane interface. Advances via fundamental understanding of both hydrogen and oxygen evolution reactions (HER/OER) leading to novel materials will be in conjunction with critical improvements in membrane and ionomers and gas evolution electrodes with corresponding characterization and testing. Progress towards these goals under a three-year multifaceted and comprehensive effort will be described wherein Northeastern University (NEU) will present catalyst development and characterization (both in situ and ex situ). University of Delaware (UD) will showcase improvements in ionomer and membrane materials. In addition, close collaboration with National Laboratory partners with Lawrence Berkeley National Lab (LBNL) participating in multiscale modeling and computation in close concert with Sandia National Laboratory (SNL) providing MD simulations of the membrane catalyst interface and National Renewable Energy Laboratory (NREL) providing advanced ionomers, durability protocols and validation will be described.
Anion exchange membrane electrolyzers (AEMELs) are ideally suited with a low-cost profile enabled by platinum group metal (PGM)-free catalysts, low fluorine content membranes, and a less corrosive environment for cell separators. This presentation will showcase state of the art stable, high-conductivity, and high-strength AEMs, stable and active PGM-free catalysts for hydrogen and oxygen evolution reaction (HER/OER), and high performance electrode architectures that together can unlock the cost advantages of AEMELs. If successful, the developed technology can meet FCTO efficiency targets, delivering carbon-neutral hydrogen at $2/kg while simultaneously enabling higher penetrations of wind and PV electricity on the grid.
The overall goal is cell level performance of 1.62 V at 1 A/cm2, which meets the FCTO efficiency target of 43 kWh/kg. Component performance targets have been established using a porous electrode model to support the overall cell performance target. This is at the modeled scale of 50,000 kg/day and operating at 1 A/cm2 resulting in hydrogen cost at $2.15, $1.82, or $1.76/kg, respectively (2, 20, 200 plants). In the low-volume manufacturing case, it is still possible to meet the cost target by operating near 2 A/cm2, sacrificing some efficiency.
(Invited) Progress in Alkaline Membranes and Alkaline Membrane Fuel Cells at the National Renewable Energy Lab
Authors: Neyerlin Ami , Strasser Derek , Antunes C. M. , Meek Kelly , Owczarczyk Zbyslaw R. , Pivovar Bryan S. 
Published: February 2020

Alkaline membrane fuel cells are of high interest because they offer the ability to use lower cost catalyst and separator materials: two cost limitations of polymer electrolyte fuel cell systems. The performance advances of these systems has been fairly remarkable as power densities around 2 W/cm2 and current densities above 5 A/cm2 have now been demonstrated.(1) Efforts at NREL have focused on the development of novel ionomers for use in electrodes and membranes. However most of the improvements in performance have arisen due to the impact of electrode fabrication and operating conditions. The different advances that have led to improved performance and durability of these systems as well as remaining challenges will be discussed.
These systems and the results presented are closely tied to the area of alkaline membrane fuel cells where Shimshon Gottesfeld has been an early champion. Beyond the current research portfolio, the presenter for this talk, a former post-doc under Shimshon Gottesfeld will talk about his interactions with Shimshon, with a specific focus on the area of alkaline membrane fuel cells.
References

1. Omasta, T. J. et al. Energy Environ. Sci. 11, 551–558 (2018).
Biochemical Oxygen Demand Microelectrode for Quantifying Concentration Gradients in Anaerobic Biofilms
Authors: Elharati Mohamed A. , Mohamed Abdelrhman , Beyenal Haluk 
Published: February 2020

Biochemical oxygen demand (BOD) is one of the widely used parameter to determinate the level of organic pollution in water. The standard method, BOD5 assay, is commonly used to measure BOD concentration but it takes a long time and cannot be integrated for online measurements. Additionally, BOD5 cannot be used to measure BOD in microscale systems, especially in anaerobic biofilms where the oxygen is absent. Because of the limitation of available tools for quantifying BOD concentration within anaerobic biofilms, a new, simple and miniaturized tool is needed for measuring local BOD concentrations in biofilms.
The goal of this work is to develop a BOD microelectrode for quantifying concentration gradients in anaerobic biofilms. The developed BOD microelectrode uses an anaerobic mixed-culture-anodic biofilm as a transducer, which is grown on a carbon fiber tip diameter. The carbon fiber microelectrode acts as the working electrode, which is polarized using a potentiostat. A 100 µm platinum wire counter electrode and a Ag/AgCl-wire pseudo reference electrode are used to complete the electrochemical cell. The BOD microelectrode components are enclosed in a glass outer case. The BOD microelectrodes were calibrated using a standard BOD solution. The performance of the BOD microelectrode was assessed including response time and the linear BOD concentration range. Finally, concentration profiles in an anaerobic biofilm were measured to demonstrate its use.
Highly Specific Detection of Oxytocin in Saliva
Authors: Rana Muhit , Weber Andrew , Manoukian Mourad , Dweik Badawi , Argun Avni 
Published: February 2020

Oxytocin is a nine amino acid peptide hormone secreted in hypothalamus that is best known for its significant role in stimulating labor and milk ejection throughout the course of child birth and breastfeeding. As an inducer, oxytocin is used in more than 13 percent of child births in the United States. It is also a neurotransmitter that mediates the dynamic function of the brain and a variety of complex social behaviors including affiliation, sexual behavior, social recognition, and aggression. A similarly structured vasopressin hormone is secreted from the same region in hypothalamus and often competes with oxytocin to bind to existing antibodies. This results in poor specificity and major cross-reactivity issues for the existing oxytocin immunoassays. Mass spectrometry methods combined with liquid chromatography resolve these issues; however, high costs of sophisticated instrumentation, lengthy retention times, and the need for skilled technicians limit their suitability for point-of-care operation.
We present here an aptamer-based electrochemical assay for real-time and point-of-care detection of oxytocin in non-invasive clinical samples such as saliva to allow perinatal monitoring of oxytocin during child birth. Our approach provides highly sensitive and specific detection at low cost through the use of disposable electrodes. Our optimized antibody alternative aptamer has been developed, characterized, and validated as a proof-of-concept oxytocin binder and incorporated to commercially available screen printed electrodes (SPEs). We have developed a method that is specific to aptamer-bound oxytocin to generate signal as electrochemical readout. Our preliminary results confirm that our aptamer-based assay can detect as low as 10 pg/mL (~10 picomolar) oxytocin in saliva samples in less than 5 minutes with minimal false positive or false negative signals.
Electrochemical Reduction of Acetochlor at Carbon and Silver Cathodes in Dimethylformamide
Authors: Couto Petro Ana G. , Peters Dennis G 
Published: February 2020

Chloroacetamides are a popular class of herbicides often used against weeds in a variety of major crops, such as corn, cotton, rice, and soybeans.1 One such herbicide is acetochlor or 2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide that, since its registration in 1994, has become commonly used in the United States.2 Although acute and chronic toxicological effects in humans of acetochlor at low environmental exposures are still unknown, animal tests have shown in some species the development of lung tumors, nasal epithelia, and thyroid cancer; for that reason, the U.S. EPA classifies acetochlor as likely to be carcinogenic in humans.3,4 This project’s primary objective is to investigate the electrochemical behavior of acetochlor and to develop a possible degradation method for acetochlor as well as other chloroacetamide-type herbicides.
To the best of our knowledge, previous electrochemical studies of acetochlor have been performed only via anodic Fenton treatment;5 electrochemical reduction has not yet been pursued. In the present study, we have conducted cyclic voltammetry to evaluate the electrochemical behavior of acetochlor at carbon and silver cathodes in dimethylformamide (DMF) containing 0.05 M tetramethylammonium tetrafluoroborate (TMABF4). Glassy carbon is a traditional electrode material and silver has been shown to be catalytic for the cleavage of carbon–halogen bonds. Reduction of acetochlor at silver (–0.95 V vs. Cd/Hg) occurs at more positive potentials than at carbon (–1.4 V vs. Cd/Hg) and affords primarily the dechlorinated parent compound, N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide. In addition, reduction of acetochlor in the presence of electrogenerated nickel(I) salen (–0.95 V vs. Cd/Hg) indicates that nickel salen complexes can be an alternative to silver in order to achieve catalytic reduction. Controlled-potential (bulk) electrolysis coupled with traditional analytical methods such as gas chromatography–mass spectrometry (GC–MS) led to the identification and quantitation of reduction products.

References

Lamberth, C. Chloroacetamide Herbicides. In Bioactive Carboxylic Compound Classes, Pharmaceuticals and Agrochemicals, Lamberth, C., Dinges, J., Eds.; Wiley: Germany, 2016; pp 293–302.

Lerro, C. C.; Koutros, S.; Andreotti, G.; Hines, C. J.; Blair, A; Lubin, J.; Ma, X.; Zhang, Y.; Beane Freeman, L. E. Int. J. Cancer.
2015, 137, 1167–1175.

U.S. Environmental Protection Agency. Acetochlor (Harness) Pesticide Petition Filing 1/00. Fed Regist.
2000, 65, 3682–3690.

Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Acetochlor. EPA 738-R-00-009; U.S. Environmental Protection Agency (U.S. EPA): 2006, 1–9.

Friedman, C. L.; Lemley, A. T.; Hay, A. J. Agric. Food Chem.
2006, 54, 2640–2651.
Crosslinkable Nitroxide Radical Polymer for Energy Storage Applications
Authors: Wang Shaoyang , Easley Alexandra Danielle , Li Fei , Lutkenhaus Jodie L. 
Published: February 2020

Due to the amount of waste generated by lithium ion batteries (LIB) disposal, a more environmentally friendly option such as organic batteries, is desired to fulfill the need of this large market. For many years, alternatives to LIBs have been researched, including the use of conductive polymers for completely organic batteries. Redox-active polymers, such as conjugated polyaniline and organic radical poly(2,2,6,6-tetramethylpiperidinyloxy-4-ylmethacrylate) (PTMA), are being studied as electrode materials for organic batteries. As linear PTMA may dissolve in the electrolyte solution and thus degrade battery capacity, crosslinked PTMA is gaining interest as a cathode material. A balance must be struck, however, as diffusion of the electrolyte solution into the polymer may become limited at sufficiently high crosslink density. To balance these competing mechanisms, a random copolymer consisting of PTMA monomer and glycidyl methacrylate (GMA), a UV and thermally crosslinkable monomer, is synthesized (P(TMA-GMA)) and the mechanism of redox activity is studied.
This new PTMA copolymer is synthesized using free radical chain-growth polymerization and is then oxidized to produce the characteristic organic radical. Linear P(TMA-GMA) is characterized using UV-VIS, NMR spectroscopy, and gel permeation chromatography. The effect of crosslinking on the thermal properties and the temperature for thermally induced crosslinking is analyzed using differential scanning calorimetry. The crosslink density is calculated for each composition using the linear P(TMA-GMA) molecular weight and solvent uptake of the crosslinked P(TMA-GMA). Determining the most favored crosslink density is necessary for balancing electrolyte diffusion with the dissolution of the polymer. The electrochemical properties of the crosslinked P(TMA-GMA) is studied using cyclic voltammetry (CV) to determine if crosslinking impacts the redox properties.
Preliminary results have found that the crosslinked P(TMA-GMA) exhibits a change in the shape of the CV curve and peak heights, associated with some change in the crosslinked polymers electroactivity. In addition, the crosslink density of the P(TMA-GMA) with 5 mol% GMA is quantified and is similar to previous studies of poly(ethylene glycol). Finally, the thermal properties are represented by a glass transition temperature that did not significantly change with varying GMA content. This new P(TMA-GMA) shows promise for application in organic batteries by providing a processable yet crosslinkable alternative to PTMA.
Holey Bismuth for Selective Electrochmical CO2 Reduction
Authors: Yang Chih-Wen , Huang Kuo-Wei , Tung Vincent , Zhong Shenghong , Yang Xiulin 
Published: February 2020

Because of the consumption of fossil fuel, CO2 emission, a product of burning fossil fuel, causes the global warming. Electrochemical CO2 reduction reaction (eCO2RR) provides a solution that allows to reduce the carbon emission and produce useful products. Among those CO2 reduction products, formic acid is one of the most attractive candidates because it has higher volumetric capacity of H2 (53 g H2/L) and can release H2 by catalyst under room temperature, which makes it a promising energy carrier.[1] Also, it is feasible to transport since it is nonflammable and stable under room temperature. Among the materials for eCO2RR, bismuth has better selectivity toward formate production (Faraday efficiency > 80%).[2]

However, production rate, partial current density toward formate, of those catalyst remained low. One of the approach to boost the production rate is to increase the surface area of catalyst. By creating the porous structure, surface area of catalyst will be increased and thus enhances the production rate of formate. In this work, we successfully synthesized sponge-liked bismuth by chemical vapor deposition (CVD) method for eCO2RR. As results, it shows an excellent current density (28 mA/cm2) and faraday efficiency toward formate (95%) in moderate applied potential -1.05 V (vs. reversible hydrogen electrode (RHE)) under low catalyst loading. Furthermore, Comparing to electroplating bismuth, sponge-liked bismuth have double current density under same electroactive surface area.
[1] Eppinger, J. and K.W. Huang, Formic Acid as a Hydrogen Energy Carrier
. Acs Energy Letters, 2017. 2(1): p. 188-195.
[2] Larrazabal, G.O., A.J. Martin, and J. Perez-Ramirez, Building Blocks for High Performance in Electrocatalytic CO2 Reduction: Materials, Optimization Strategies, and Device Engineering. J Phys Chem Lett, 2017. 8(16): p. 3933-3944.