bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Ink Composition and Operation Parameters on the Performance of Fe-N-C
Authors: Gallenkamp Charlotte , Kübler Markus , Kramm Ulrike Ingrid 
Published: February 2020

The application of proton exchange fuel cells (PEFCs) in the automotive sector is rising to be an alternative to petroleum fuel based transportation. Nevertheless, the obstacle of cost reduction of the PEFC remains, which is due to highly expensive Pt catalysts on the cathode side for oxygen reduction reaction (ORR).[1] A possible way to substitute Pt for ORR is the use of Fe-N-C-catalysts which have been shown to be a promising option.[2]
For Fe-N-C-catalysts the required catalyst loading needs to be significantly higher than for Pt-based catalysts in order to achieve sufficient current densities. This leads to a change in catalyst layer thickness of roughly one order of magnitude where transport phenomena of gases and liquids become more important.[3] Based on this, the gap between Pt/C and Fe-N-C at high current densities is significantly higher compared to the kinetic controlled region. Therefore, further optimization is needed in order to enhance activity also under high current flow. In addition to this, it need to be understood to what extent problems in the transport properties affect the durability behavior of Fe-N-C catalysts in fuel cells.
The ionomer distribution and loading of the catalyst layer has found to be crucial for proton transport towards the active sites, but also influences the hydrophilicity of the catalysts pores which enhances gas transport resistance. [1] In addition, it has been shown that the preparation of the membrane electrode assembly (MEA) for the fuel cell plays a key role. [3] The widely used hot-pressing technique might influence the catalyst layer pore size which is also an important parameter for species transport.
In this work, different catalyst to ionomer ratios are evaluated in fuel cell tests for Fe-N-C catalysts. Furthermore, the preparation by hot-pressing is investigated in respect to the application of different compression pressures. The results are brought in relation to structural investigations of the MEAs and serve for the validation of a theoretical model.
[1] S. Komini Babu, et al. ACS Appl. Mater. Infertaces 2016, 8, 32764-32777 (2016)
[2] U.I. Kramm, et al. J. Am. Chem. Soc., 138 (2), 635–640 (2016)
[3] X. Yin, et al. ECS Transactions, 77 (11) 1273-1281 (2017)
[4] S. Komini Babu, et al. Journal of The Electrochemical Society, 164 (9), F1037-F1049 (2017)
Modulating Proton and Electron Transfer Dynamics in Molecular Electrocatalysis Using Membrane-Covered Self-Assembled Monolayers
Authors: Mennel Jason , Gautam Rajendra , Supakul Skye , Barile Christopher J. 
Published: February 2020

Many reactions central to the development of renewable energy devices such as the O2 reduction reaction, the O2 evolution reaction, and the CO2 reduction reaction require the transfer of multiple electrons and protons. These reactions proceed by a variety of mechanisms depending upon the relative rates of these transfer events. We are developing electrode frameworks that enable control over proton and electron transfer kinetics to molecular catalysts such that the selectivity of catalysts can be improved. These electrodes contain a transition metal catalyst such as a Cu-triazole or an Fe-porphyrin attached via a self-assembled monolayer (SAM), which is then covered by a proton-permeable membrane. Initial studies have utilized a lipid monolayer modified with aliphatic proton carriers as the proton-permeable membrane. The kinetics of proton transfer to the catalyst are controlled by changing the quantity and identity of proton carriers in the membrane. By altering the identity of the SAM, which can be facilely done using a modular azide-alkyne click chemistry approach, the kinetics of electron transfer to the catalyst can also be controlled.
One grand challenge in designing catalysts for both the O2 and CO2 reduction reactions is selectivity. We show that the selectivity of a Cu-based O2 reduction catalyst can be improved by controlling proton transfer rates such that the catalyst produces solely water. In contrast, the same Cu catalyst produces ~10% H2O2 side product when proton transfer is not regulated. We also discuss how modulating proton and electron transfer kinetics affects the selectivity of molecular CO2 reduction catalysts and the performance of Ni-based O2 evolution catalysts.
(Invited) Hydrogen and Fuel Cells Enabled through the U.S. Department of Energy
Authors: Satyapal Sunita 
Published: February 2020

Today the technology around generating efficient and sustainable energy is rapidly evolving and hydrogen and fuel cells are emerging, versatile examples within a portfolio of options. Through the dedication and contributions of numerous researchers funded by the U.S. Department of Energy’s (DOE) in collaboration with the private sector, hydrogen and fuel cell technologies are now a commercial reality. This presentation will cover the history of DOE’s efforts along with examples of breakthroughs by leading contributors in electrochemistry. This is an exciting time in the fuel cell industry with over ten thousand commercial fuel cell vehicles sold or leased, hundreds of fueling stations worldwide, and more than a quarter of a million stationary fuel cells providing clean, reliable power. DOE’s Fuel Cell Technologies Office (FCTO) within the Office of Energy Efficiency and Renewable Energy (EERE) addresses key technical barriers faced by hydrogen and fuel cells through a comprehensive portfolio of early-stage research and development (R&D) with the potential to meet technical and cost targets that enable competitiveness with incumbent technologies in the market, aligned with national priorities.
The presentation will cover technology status versus targets as well as an overview of the global landscape in hydrogen and fuel cells. International government collaborations through partnerships such as the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE) are contributing to progress and can enable large-scale deployment worldwide. The talk will cover the broad context of hydrogen within the energy system – the DOE’s H2@Scale initiative which will enable innovations to generate cost-competitive hydrogen as an energy carrier, coupling renewables, as well as baseload power generation, enhancing resiliency and avoiding curtailment. Hydrogen can be stored, distributed and used as a fuel or feedstock in transportation, stationary or back-up power and multiple industrial sectors, while creating an additional revenue stream for existing baseload and variable generation assets. The presentation will also provide an overview of national and regional efforts within the United States related to hydrogen and fuel cells and potential opportunities within the region.
(Invited) Materials and MEA Design Impact on the High-Current Density Performance of PEMFCs
Authors: Orfanidi Alin , Harzer Gregor S. , Madkikar Pankaj , Schulte Nicole , Rheinländer Philipp J. , El-Sayed Hany A , Gasteiger Hubert A. 
Published: February 2020

In order to achieve platinum specific power densities of <0.1 gPt/kW, which are required for the large-scale implementation of fuel cell electric vehicles (FCEVs) powered by proton exchange membrane fuel cells (PEMFCs), both the mass activity of the catalyst for the oxygen reduction reaction (ORR) and the high-current density performance of PEMFCs must be improved [1]. The latter strongly depends on the membrane electrode assembly (MEA) materials and design, for example: i) on the morphology of the catalyst support [2]; ii) on the distribution of the Pt nanoparticles on/within the primary particles of the carbon support [3,4]; iii) on the surface functionalization of the carbon support [5]; and, iv) on the ionomer distribution in the electrode, which is affected by the solvents used for catalyst ink preparation [6].
In this contribution, we will examine the influence of Pt nanoparticle distribution, carbon support surface modification, and various catalyst ink solvents on the high-current density performance of MEAs under differential flow conditions. This will be accompanied by fuel cell diagnostics (oxygen and proton transport resistance measurements in the cathode electrode) and by ex-situ characterization methods.

References

[1] A. Kongkanand, M. F. Mathias; J. Phys. Chem. Lett. 7 (2016) 1127.
[2] V. Yarlagadda, M. K. Carpenter, T. E. Moylan, R. S. Kukreja, R. Koestner, W. Gu, L. Thompson, A. Kongkanand; ACS Energy Lett. 3 (2018) 618.
[3] Y.-C. Park, H. Tokiwa, K. Kakinuma, M. Watanabe, M. Uchida; J. Power Sources 315 (2016) 179.
[4] G. S. Harzer, A. Orfanidi, H. El-Sayed, P. Madkikar, H. A. Gasteiger; J. Electrochem. Soc. 165 (2018) F770.
[5] A. Orfanidi, P. Madkikar, H. A. El-Sayed, G. S. Harzer, T. Kratky, H. A. Gasteiger; J. Electrochem. Soc. 164 (2017) F418.
[6] A. Orfanidi, P. J. Rheinländer, N. Schulte, H. A. Gasteiger; J. Electrochem. Soc. 165 (2018) F1254.
(Invited) Polymer Electrolyte Fuel Cell Catalysis - Older Goodies and New Concepts
Authors: Schmidt Thomas J. 
Published: February 2020

Polymer Electrolyte Fuel Cell (PEFC) Research has been performed over the more than 30 years now with the results that both stationary and automotive systems are commercially available. Two prominent examples are the Enefram stationary systems in Japan with more than 250 000 installed systems, and several commercial and pre-commercial fuel cell cars from e.g. Toyota, Hyundai and Honda.
Catalysis in PEFC has been mainly dominated by research on the oxygen reduction reaction over the last 20 years; however specifically for the stationary system, anode catalysis using impure CO containing hydrogen streams from reforming reactions are still quite important but less prominent nowadays.
In this contribution, a subjective selection of important new PEFC catalysis concepts as well as still important elder goodies from the last 20 years will be given and an attempt is made to connect this summary to Shimshon Gottesfeld's work.
(Invited) Insights from the inside: Imaging Water in the Porous Structures of Fuel Cells
Authors: Büchi Felix N. , Eller Jens , Xu Hong , Boillat Pierre 
Published: February 2020

Imaging is a powerful tool to understand and optimize the water management in acidic and alkaline fuel cells. A topic that has also been a subject of collaboration between the authors and Shimshon Gottesfeld.
Neutron radiography is a truly non-destructive method with the advantage of large fields of view, easy penetration of structural materials and negligible radiation damage. This allows for exposure over long periods of operation and therefore dedicated parameter studies. In alkaline fuel cells the water management is of high importance and a crucial point to optimize performance. Insight will be presented fon different scales, from the differential cell to the stack level using neutron radiography (Figure 1).
X-ray tomographic microscopy is a complementary imaging method when information on the pore scale in a small field of view and fast dynamics are required. Recent developments and insights from sub-second synchrotron based tomographic imaging on the dynamics of water in the gas diffusion layer will be discussed. Figure 2 shows a series of 0.1s tomographic scans after a current jump from OCV to 0.5 A/cm2, showing the dynamic development of liquid saturation in the GDL.

Figure 1
(Invited) Switching from Low-Density to High-Density Polyethylene As a Base Material for Radiation-Grafted Anion-Exchange Membranes Leads to Much Higher Alkaline Membrane Fuel Cell Performances
Authors: Wang Lianqin , Varcoe John R. 
Published: February 2020

This presentation will describe the development of a new type of radiation-grafted anion-exchange membrane (RG-AEM) made from high-density polyethylene (HDPE) base material, which contains benzyltrimethylammonium cationic head-group chemistry. This RG-AEM has an ion-exchange capacity (IEC) of 2.4 meq g-1, and is less than 30 μm in thickness (when fully hydrated) with an ultimate tensile strength of ca. 35 MPa (elongation to break of 280 %). It exhibits a hydroxide conductivity of 214 ± 2 mS cm-1 at 80 °C in a 100% relative humidity (RH) atmosphere, which decays to 195 mS cm-1 after 500 h exposure to these same ex situ conditions.
Despite exhibiting similar ex situ characteristics to a low-density polyethylene (LDPE) analogue RG-AEM (of similar hydrated thickness and IEC), the HDPE-RG-AEM yields significantly higher beginning-of-life H2/O2-benchmark alkaline membrane fuel cell power densities (see Figure): 2.55 W cm-2 peak power density was achieved at 80 °C with 92% RH H2/O2 gas supplies (no back pressure applied). Internal area specific resistances of < 30 mΩ cm2 were recorded.

Figure 1
Electrochemical Investigation of Halogenated Hydroxybenzonitriles at Silver Cathodes in Dimethylformamide
Authors: Nugen Tyler J , McKenzie Eric C.R. , Peters Dennis G 
Published: February 2020

Chloroxynil (3,5-dichloro-4-hydroxybenzonitrile), Bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), and Ioxynil (3,5-diiodo-4-hydroxybenzonitrile) belong to a group of halogenated phenols commonly used as herbicides to control broad-leaved weeds. Functioning as disruptors of oxidative phosphorylation, these compounds have grown in popularity in recent years as alternatives to atrazine, particularly bromoxynil (1800–2200 tons applied per year).1,2 In the environment, all three herbicides can undergo hydrolysis as well as enzymatic degradation to the corresponding benzamide (3,5-dihalo-4-hydroxybenzamide) and subsequently to the benzoic acid (3,5-dihalo-4-hydroxybenzoic acid), both of which have the possibility of persisting in soil.3,4 As a result, an efficient means of degrading the parent compounds is necessary. Sokolova and co-workers5 have investigated the electrochemical reduction of these hydroxybenzonitriles; however, their studies employed mercury working electrodes, which are known to be extremely toxic and hazardous.
Silver has long been praised as an advantageous cathode for remediation of environmental pollutants due to its affinity for halides.6 In the present study, we propose to use silver cathodes to investigate the electrochemical behavior of chloroxynil, bromoxynil, and ioxynil in dimethylformamide (DMF). Cyclic voltammograms for each compound in DMF containing 0.05 M tetramethylammonium tetrafluoroborate (TMABF4) show widely different behavior between the three herbicides: chloroxynil exhibits one cathodic peak (–0.74 V), whereas bromoxynil displays four cathodic peaks (–0.40 V, –0.65 V, –1.23 V, and –1.51 V) as does ioxynil (–0.20 V, –0.30 V, –0.58 V, and –1.66 V). All potentials are versus a cadmium-mercury amalgam reference electrode. Bulk electrolyses performed with 0.05 M TMABF4–DMF result in a wide product distribution in addition to different n values for each substrate.

Holtze, M.; Sorensen, S. R.; Sorensen, J.; Aamand, J. Environ. Pollut.
2008,
154, 155–168.

Lovecka, P.; Thimova, M.; Grznarova, P.; Lipov, J.; Knejzlik, Z.; Stiborova, H.; Nindhia, T. G. T.; Demnerova, K.; Ruml, T. BioMed Res. Int.
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Nielsen, M. K. K.; Holtze, M. S.; Svensmark, B.; Juhler, R. K. Pest Manag. Sci.
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63, 141–149.

Roberts, T. R.; Hutson, D. H.; Lee, P. W.; Nicholls, P. H.; Plimmer, J. R., Metabolic Pathways of Agrochemicals: Part 1: Herbicides and Plant Growth Regulators. 1998.

Sokolova, R.; Hromadova, M.; Fiedler, J.; Pospisil, L.; Giannarelli, S.; Valasek, M. J. Electroanal. Chem.
2008,
622, 211–218.

Martin, E. T.; McGuire, C. M.; Mubarak, M. S.; Peters, D. G. Chem. Rev.
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Mechanistic Insight into Photoelectrochemical Conversion of Alkyl Monohalides to Aldehydes
Authors: Lee Ryan , Hosseini Seyyedamirhossein , Peters Dennis G 
Published: February 2020

Aldehydes are important starting materials for a variety of chemical processes such as the synthesis of food preservatives. For example, certain aldehydes may be used for improving sensory quality and shelf-life of milk.1 Synthesis of aldehydes from alkyl monohalides involves a multi-stage reaction which various reagents are needed for each step of the conversion.2 Previous works from our laboratory showed that simultaneous introduction of UV radiation and oxygen during electrolysis of an alkyl monohalide with electrogenerated nickel(I) salen affords the corresponding aldehyde or ketone with relatively high yield (Figure 1). 3,4

The purpose of the present work is to elucidate the mechanism for the above-mentioned conversion. For this purpose, a solution of 1-bromooctane (5 mM) and nickel(II) salen (5 mM) was electrolyzed at –1.0 V in DMF–water containing TMABF4 (0.10 M). At the end of the electrolysis, modified nickel(II) salen was separated from the electrolysis mixture with application of normal phase flash chromatography. Modified nickel(II) salen was dissolved in DMF–water containing TMABF4 (0.10 M) and exposed to UV radiation (440 nm); the product of the photoreaction was identified as octanal. In respect, we believe the reaction passes through a series of the intermediates are proposed in Figure 2. This reaction features a single-step and efficient method for transforming alkyl monohalides into the desired aldehydes.
References

Kelly, P. Woonton, B. W. Smithers, G. W. Woodhead. Woodhead Publishing Ltd. 2009. 170.

Hendrickson, J. B., Sternbach, D. D. J. Org. Chem. 1975, 40, 3450.

Vanalabhpatana, P.; Peters, D. G. Tetrahedron Lett.
2003, 44, 3245.

Vanalabhpatana, P.; Peters, D. G. J. Electroanal. Chem.
2006, 593, 34.

Figure 1
Disposable and Inexpensive Electrochemical Biosensor to Detect Ciprofloxacin
Authors: Trevino Nicholas Paul , Ganta Deepak , Montes William , Guzman Carlos 
Published: February 2020

Ciprofloxacin hydrochloride, USP, a fluoroquinolone, is the monohydrochloride monohydrate salt of 1-cyclopropyl-6-fluoro-1, 4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid. Ciprofloxacin (Cipro) is an antibacterial medicine used to treat infected open wounds, by targeting bacteria infiltrating and rendering useless to multiplying using attacking its genetic makeup directly. In 2010, over 20 million prescriptions were written, making it the 35th-most commonly prescribed generic drug and the 5th-most commonly prescribed antibacterial in the U.S. There is also a huge demand for the inexpensive and compact sensor to detect the presence of ciprofloxacin in water. Its wide use motivated us to develop an electrochemical sensor to detect the presence of the ciprofloxacin in aqueous solutions.
Inexpensive and disposable screen-printed electrode was used as our electrochemical sensor. We tested different aqueous solutions with varying concentrations of Cipro, and measure the sensitivity. The sensors have three electrodes, with the working and counter electrode being composed of graphite, and the reference electrode composed of Ag/AgCl and sodium hydroxide (NaOH) is the supporting electrolyte. During the preparation of the Ciprofloxacin, NaOH is added in order to neutralize, which also acts as a supporting electrolyte. Finally, Cipro is then added to 2mL of DI water and disturbed until a solution is formed. The prepared solution is varied for the desired concentration is then drop-coated onto the sensing part in the electrochemical sensor, making sure the entirety of the sensing section is covered. The sensor is then connected to the potentiostat, and the test is performed. The redox reaction was measured using a potentiostat (Biologic). With these different concentrations, testing was conducted through the use of cyclic voltammetry (CV) and chronoamperometry (CA). From the CV curves, we were able to determine the relationship between the concentrations(nM) and the current. Our data shows that the current has a steady decrease as the concentrations increase. The slope provided from this relationship is used to provide the sensitivity of the testing method produced. The sensitivity was measured to be found to be .0029nM over a linear range of (0.1nM - 2nM).
Developing Plasmonic Imaging Technique to Understand Battery Solid Electrolyte Interface Formation and Li Nucleation in-Situ
Authors: Shan Xiaonan , Yang Chaojie 
Published: February 2020

During the operation of lithium-ion battery (LIB), a solid electrolyte interface (SEI) layer forms on the anode electrode materials due to side reactions with the electrolyte solvent and salt. It is essential to the performance of LIBs and it decides the initial capacity loss, self-discharge characterizstics, cycle life and safety. Therefore to understand the SEI formation is extremely important for battery research. Currently, most of characterization methods of SEI are based on electron microscope, although powerful, it is difficulty to directly map the SEI formation in-situ.
We have developed a novel plasmonic imaging technique to image the local SEI formation and measure the electrochemical reaction of the anode electrodes. Unlike conventional electrochemistry that measures the electrical current from entire electrode, the plasmonic-based electrochemical microscope (PECM) technique is based on sensitive imaging of surface plasmonic signal caused by electrochemical reaction, which is measured optically, thus allowing for fast and non-invasive imaging of electrode processes. PECM can image localized chemical reactions on the electrode surface ins-situ, this information will be extremely important for us to understand SEI formation and electrochemical reaction on the anode electrode. The electrochemical reaction will always be accompanied by a conversion of the chemical species between oxidized and reduced states, and plasmonic imaging is extremely sensitive to the species generated (or consumed) on electrode materials. Therefore, the PECM has great potential to characterize the local electrochemical reactions and energy storage process.