bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of Resonance Structure on Alkaline Stability
Authors: Maurya Sandip , Lee Kwan-Soo , Fujimoto Cy , Kim Yu Seung 
Published: February 2020

Anion exchange membrane fuel cells (AEMFCs) have been a topic of extensive research from academia and industry as an alternative to proton exchange membrane fuel cells (PEMFCs). The AEMFCs offer benefits over PEMFCs such as facile fuel oxidation and enhanced oxygen reduction reaction catalysis1. However, the chemical stability of anion exchange membrane needs to be improved as most commonly used benzyltrimethyl ammonium cationic group undergoes direct nucleophilic substitution reaction, which results in loss of conductivity and fuel cell performance. One of the approaches to enhance the chemical stability is introducing electron conjugation into cationic functional group. Previous study demonstrated that the conjugated guanidinium possess better stability than non-conjugated guanidinium2.
Herein, we report the progress on resonance stabilization of the guanidinium functional group. The extended-resonance stabilized guanidinium functionalized poly(phenylene) (PP-TMG) AEM was synthesized from the Diels-Alder poly(phenylene) by acylation reaction followed by activated fluorophenyl-guanidine reaction3. The alkaline stability of PP-TMG was compared with benzyltrimethyl ammonium-poly(phenylene) (PP-BTMA) and hexamethylenetrimethyl ammonium-poly(phenylene) (PP-HTMA). Spectroscopic analysis with small molecules and cationic group tethered polymers will be also provided to discuss the resonance stabilization effect.

Acknowledgement

This work is supported by the US Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technology Office (Program Manager Dr. David Peterson).

References:

(1) Varcoe, J. R.; Atanassov, P.; Dekel, D. R.; Herring, A. M.; Hickner, M. A.; Kohl, P. A.; Kucernak, A. R.; Mustain, W. E.; Nijmeijer, K.; Scott, K.; Xu, T.; Zhuang, L. Energy Environ. Sci.
2014, 7 (10), 3135–3191.
(2) Kim, D. S.; Fujimoto, C. H.; Hibbs, M. R.; Labouriau, A.; Choe, Y.-K.; Kim, Y. S. Macromolecules
2013, 46 (19), 7826–7833.
(3) Kim, D. S.; Labouriau, A.; Guiver, M. D.; Kim, Y. S. Chem. Mater.
2011, 23 (17), 3795–3797.
Extracting Material Properties from Relaxation Experiments
Authors: Haile Sossina M 
Published: February 2020

Redox active oxides, with mixed ionic and electronic conductivity (MIEC), are critical components in a wide range of energy technologies, serving as electrodes in fuel cells and batteries, and as reactive substrates in solar-driven thermochemical reactors. Accurate knowledge of the surface reaction rate constant, k
S, is essential for both optimal design of components using existing materials and rational discovery of new materials with enhanced catalytic activity. A variety of relaxation methods have been used extensively to determine k
S. Such approaches rely on the change in some measurable property, most commonly conductivity, upon application of a step change in gas-phase oxygen partial pressure. Under the appropriate experimental conditions, the rate at which the property changes in response to the change in gas-phase oxygen chemical potential provides a direct measure of the material kinetic parameters. Here, we present several considerations relevant to accurate extraction of these parameters, with particular focus on identifying relaxation occurring due to thermodynamic rather than material kinetic reasons. Furthermore, while the electrical conductivity relaxation (ECR) method is one of the most widely employed relaxation techniques because of the ease with which high precision conductivity measurements can be made using samples of almost arbitrary dimensions, ECR is impractical for the evaluation of a material in which the change in conductivity in response to change in oxygen partial pressure is extremely small. For such materials mass relaxation emerges as a viable alternative measurement approach. To this end, we describe a high temperature mass relaxation apparatus based on a gallium phosphate piezocrystal microbalance that enables measurements at temperatures as high 700 °C.
(Invited) Sulfur Poisoning of Ni-Based SOFC-Anodes – Short and Long Term Behavior
Authors: Weber André , Dierickx Sebastian , Russner Niklas , Ivers-Tiffée Ellen 
Published: February 2020

Solid Oxide Fuel Cells (SOFCs) enable a highly efficient, environmentally-friendly power generation. One major problem of SOFCs working under real conditions are the sulfur compounds contained in almost all available fuels as natural gas, diesel reformate or gas from hydrothermal gasification of biomass (1),(2). If the sulfur is not properly removed by an upstream desulfurization unit even small amounts of sulfur in the ppm range affect the performance of SOFCs. Previous studies showed that the initial performance loss observed after adding sulfur to the fuel is related to a poisoning of the Ni-electrocatalyst in the Ni/YSZ-cermet anode.
In this contribution the impact of sulfur on the short term and long term behavior of Ni-based cermet anodes will be discussed. Sulfur species are chemisorbed on the Ni-surface (3), blocking the adsorption sites and the surface diffusion of reactants and reaction products. By means of electrochemical impedance spectroscopy and a subsequent analysis of the spectra by the distribution of relaxation times (4) two poisoning mechanisms could be decoupled (i) a deactivation of the catalytic watergas-shift-reaction (WGS) at the nickel surfaces and (ii) the electro-oxidation of hydrogen at the three phase boundaries (5),(6). The time constant of these mechanisms depends on the available Ni-surface area and the amount of H2S supplied to the anode and is typically in the range of several hours. Furthermore a restructuring of the Ni-surfaces accompanied by an enhanced Ni agglomeration results in an enhanced aging in the longer term.
To improve the sulfur tolerance of SOFCs a cermet anode composed of Ni and ceria, a material combination well known as sulfur tolerant catalyst, can be applied. Impedance analysis of electrolyte supported cells exhibiting a Ni/ceria cermet anodes revealed a significantly improved sulfur tolerance. It will be shown that the impact of both poisoning mechanisms can be reduced. Cells with appropriate Ni/ceria anode layers showed the ability to convert carbon monoxide by a sufficiently fast WGS and electrooxidize hydrogen with a polarization resistance below 200 mΩ·cm².
References
(1) Y. Matsuzaki and I. Yasuda, Solid State Ionics, 132 (3-4), p. 261 (2000).
(2) K. Föger and K. Ahmed, Journal of Physical Chemistry B, 109 (6), p. 2149 (2005).
(3) C. H. Bartholomew, Applied Catalysis A: General, 212 (1), p. 17 (2001).
(4) H. Schichlein, A. C. Müller, M. Voigts, A. Krügel and E. Ivers-Tiffée, Journal of Applied Electrochemistry, 32 (8), p. 875 (2002).
(5) A. Kromp, S. Dierickx, A. Leonide, A. Weber and E. Ivers-Tiffée, J. Electrochem. Soc., 159 (5), p. B597 (2012).
(6) A. Weber, S. Dierickx, A. Kromp and E. Ivers-Tiffée, Fuel Cells, 13, p. 487 (2013).
(Invited) Integrating Theory and Experiment to Design and Develop Advanced Materials for the Production of Transportation Fuels Via Catalytic Fast Pyrolysis of Biomass: Transition Metal Carbides and Phosphides
Authors: Schaidle Joshua 
Published: February 2020

As part of the DOE’s Energy Materials Network, the Chemical Catalysis for Bioenergy (ChemCatBio) Consortium seeks to overcome catalysis challenges for biomass conversion processes through the design and development of advanced catalytic materials. One such challenge being addressed by the consortium is for the catalytic fast pyrolysis (CFP) conversion process, in which biomass is heated to approximately 500°C at short contact times producing a vapor stream of over 300 different oxygenated organic compounds. This complex mixture is subsequently upgraded in the vapor phase over a heterogeneous catalyst to remove oxygen and improve the fuel properties of the condensed bio-oil. For this process, carbon efficiency has the greatest impact on the overall economics, and currently-available catalysts suffer from short lifetimes due to coke deposition and poor yields to the desired fuel-range products.
To address this challenge, the ChemCatBio consortium initiated a joint experimental and computational effort to design and develop advanced CFP catalysts based on transition metal carbide and phosphide formulations. This effort links catalyst evaluation at multiple scales, ranging from intrinsic kinetic measurements with model compounds at the mgcat scale to bio-oil production from a pine feedstock at the 100gcat scale, with computational modeling of the catalyst surface termination under reaction conditions, calculation of reaction energetics, and ultimately the integration of those energetics into a micro-kinetic model validated with experimental data. The results generated from this integrated approach are used to inform the synthesis of targeted catalyst formulations with desired properties. This presentation will provide an overview of this effort and, in the spirit of the ECS conference, will also briefly discuss the electrocatalytic properties of these transition meal carbide and phosphide materials.
(Invited) Design and Realization of New Thermochemically Active Materials
Authors: Garten Lauren , Dwaraknath Shyam , Whitehead Riley , Selvarasu Praneetha , Barcellos de Oliveira Debora R. , Chan Zamyla , Duan Chuancheng , Stone Kevin , Persson Kristin A , O'Hayre Ryan , Nocera Dan , Ginley David 
Published: February 2020

Through combining predictive theory and experiment new functional materials for thermochemical cycles and reactions such as the oxygen evolution reaction. Many of these materials include metastable polymorphs of the groundstate materials and necessitate careful optimization of the inherent defect structure for that polymorph. The often exhibit multifunctional behavior. Barium nickelate, BaNiO3, and its sub-oxides have shown potential as oxygen evolution reaction catalysts. Initial results indicate performance comparable to precious metal catalysts. We have synthesized highly phase pure materials and evaluated it in a thermochemical redox cycle. In this work we examine the structural and phase changes that occur during the redox cycling of BaNiO3 at high temperature. Thermogravimetric analysis (TGA) on sol-gel synthesized powders under reducing and oxidizing conditions indicates a reversible cycling through multiple oxidation states. The structure of the BaNiO3powder as determined by synchrotron x-ray diffraction is measured prior to and after TGA analysis to track the phase changes associated with redox cycling. Transimission electron microscopy is used to track changes in the powder surface, crystal structure and morphology. The stability of this structure over a wide range of oxidation states gives this material applicability in a number of energy applications such as electrochemical water splitting, multiferroics, and solid oxide fuel cells, all of which are discussed.
This work was funded by the Center for the Next Generation of Materials by Design, an U.S. Department of Energy, Office of Science EFRC under Contract No. DE-AC36-08GO28308 to NREL.
(Invited) Hydrogen Storage Characterization and Optimization Research Effort, Hyscore
Authors: Gennett Thomas 
Published: February 2020

The HySCORE collaboration is a DOE-FCTO funded initiative that brings together internationally recognized leaders in hydrogen storage materials characterization and development from NREL, LBNL, PNNL and NIST. This collaboration is predicated on a synergistic approach to further develop the key core-capabilities necessary for accurate evaluation of hydrogen storage materials capacity, kinetics, and sorption/desorption physio-chemical processes. Furthermore, these experts also conduct a parallel experimental-modeling collaborative approach to utilize the core-capabilities developed in order to rapidly define, model, synthesize and characterize the appropriate materials necessary for achieving the 2020 Hydrogen Storage goals set forth by DOE. The approach is multifaceted to mitigate risk and ensure success as we bridge the gap between physisorption and chemisorption to provide the basis for a new generation of hydrogen storage materials technologies. Our focus is to Develop and Enhance hydrogen storage core capabilities and to Validate claims, concepts, and theories of hydrogen storage materials. The overarching goal is to ascertain pathways and/or new materials that have the possibility to volumetric capacities of greater than 45 g/L and isosteric heats of hydrogen adsorption in the range of 15-20 kJ/mol with the additional caveats of acceptable gravimetric capacities and the ability to deliver on-demand H2 at an appropriate rate and pressure. In order to capture the benefits of reduced system cost and forecourt compression energetics, the maximum overpressure would be <100 bar of hydrogen, with a delivery temperature of greater than 150 K and as close to ambient temperature as possible.
This talk will outline the advanced characterization techniques, standardized benchmarking/protocols and capabilities. We will also highlight several new materials sets, the impact of the new characterization tools and how this has acceleratd advances in hydrogen storage materials development.
Electrochemical Nanoreactors of Mixed Metal-Oxide-Supported Noble- Metal-Nanoparticles for Efficient Oxidation of Dimethyl Ether and Ethanol
Authors: Rutkowska Iwona Agnieszka , Kulesza Pawel J 
Published: February 2020

Noble metal-based (e.g. Pt, Pd, PtRu or PtSn) nanoparticles have been recognized as the most active catalytic systems towards oxidation of small organic molecules (ethanol, dimethyl ether) at low and moderate temperatures. Although all of them can be ideally oxidized to carbon dioxide, their actual electrooxidation mechanisms can significantly differ and may result in distinct electrocatalytic efficiencies and final reaction products. There is a need to develop functionalized electrocatalytic systems exhibiting specific reactivity and capability to induce the slow reaction steps at ambient conditions.
Platinum based nanoparticles are readily poisoned by the strongly adsorbed CO-type intermediate species requiring fairly high overpotentials for their removal. For example, to enhance activity of Pt-based catalysts toward the ethanol oxidation, additional metal or metal oxide nanostructures (rhodium, iridium, tin or molybdenum and tungsten oxides) will be intentionally introduced to the electrocatalytic interface. We are also going to demonstrate that catalytic activity of platinum-based nanoparticles can be significantly enhanced through their interfacial modification with ultra-thin monolayer-type films of mixed-metal-oxo-species of titanium, cerium, zirconium or molybdenum and tungsten in their simple and polyoxometallate forms Remarkable increases of electrocatalytic currents measured under voltammetric and chronoamperometric conditions have been observed. The most likely explanation takes into account possibility of specific interactions of noble metals with transition metal oxide species as well as existence of active hydroxyl groups in the vicinity of catalytic noble metal sites. It is noteworthy that certain metal and mixed-metal oxides can generate –OH groups at low potentials: they induce oxidation of passivating CO adsorbates (e.g. on Pt) or breaking C-H bonds (e.g. during oxidation of methanol or dimethyl ether). When combined with dispersed Rh or Ir, immobilized in the organized manner in the vicinity Pt sites, they tend to weaken C-C bonds during ethanol oxidation.
We will also demonstrate that deposition of Pt and bimetallic PtRu nanoparticles onto nanostructured zirconia support results in the enhancement of their catalytic activities toward electrooxidation of dimethyl ether, another possible alternate fuel. Once more, it is reasonable to expect that the abilities of zirconia to facilitate proton mobility and to donate active hydroxyl groups at the electrocatalytic interface in acid media are responsible for the observed enhanced catalytic effects. Specific interactions with platinum and ruthenium components are also postulated.
Modeling Standing Waves in a Thin Layer Sonoelectrochemical System
Authors: Landgren Jeffrey , Strohmer Gerhard , Leddy Johna 
Published: February 2020

Recent experiments in thin layer (cell height 1 cm) sonoelectrochemistry demonstrate that sonication increases the rates of electrocatalysis. Heterogeneous electron transfer rates increase substantially upon ultrasound irradiation. A model is developed using Partial Differential Equations and the Galerkin Method (Finite Element Method) to understand catalytic effects observed when sound waves are applied in a thin layer electrochemical cell.
The cell consists of a hollow Teflon cylinder with a transducer. A three electrode system is used with the electrodes spaced equally apart and parallel to the cylinder base. The cylinder is filled with a redox probe and electrolyte solution such that a meniscus forms at the top. The transducer propagates sound waves through the solution (i.e., sonication). A comparison of cyclic voltammograms before, during, and after sonication reveals enhancement effects from the sound waves. For redox probes with slow kinetics, sonication simultaneously increases currents and appears to shift the reaction to more reversible. Data indicate that a combination of the height and shape of the meniscus play a vital role in this enhancement effect.
Numerical analysis is used in conjunction with partial differential equations to develop the model. It takes into account the shape and height of the meniscus as well as the pressure, density, elasticity, mass, and surface tension of the fluid near the meniscus. The model then reveals the standing waves of the system. Standing waves occur in a stationary medium when waves are traveling in opposite directions and cause interference with one another. In general, if this scenario occurs with waves of approximately the same amplitude there is no net change in energy, another indication that the height of the meniscus is relevant.
To help quantify this phenomenon, four equations are used. Among them are two common equations used in fluid mechanics, a conservation of momentum equation (Compressible Euler Equation), a conservation of mass equation, a boundary motion equation, and an equation that describes the surface tension on the meniscus. The boundary motion equation includes a term that describes the position of the surface. The Galerkin Method is used to convert our continuous problem to a discrete one via the weak formulation with a proper basis. A reduction of the wave equation to an eigenvalue problem gives way to our standing waves. The wave interference taking place in the cell can be seen the provided picture.
This model is important for prediction of behavior of the sound waves before and after they contact the top boundary and the role of the meniscus convexity. The model proves that the sound waves contact the meniscus and are then reflected back down into solution. Lastly, the model provides all possible standing waves in the cell. This will lead to advances in understanding the experimental system for applications in electrocatalysis.

Figure 1
Nano-Architected 3D Ultra Low-k Dielectrics
Authors: Lifson Max L. , Kim Min-Woo , Kim Bong-Joong , Greer Julia R 
Published: February 2020

Low-k dielectric materials have become increasingly critical to the semiconductor industry as the interconnect delay becomes an overwhelming portion of the total device signal delay. Many attempts at lowering the dielectric constant involve using organic materials or introducing stochastic porosity; these solutions often lack the mechanical resilience that is necessary for devices to survive in-use operation and introduce challenges for integration within traditional semiconductor processing.
We demonstrate the fabrication of a 3-dimensional nano-architected low-k dielectric material that is comprised of hollow alumina tubes and contains 99% air. It has a stiffness of 30MPa and a dielectric constant well within the ultra low-k regime (below 2.0). We utilized two-photon lithography direct laser writing followed by atomic layer deposition to create these architectures. In addition to the low dielectric constant and high mechanical stiffness, these structural meta-materials exhibit exceptional energy absorption when uniaxially compressed and favorable electrical breakdown properties.
Enhanced Thermal Durability with High Performance Lanthanum Nickelate Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Lee John In , Yang Jayoon , Kim Youdong , Park Jun-Young 
Published: February 2020

Solid oxide fuel cells (SOFCs) have been regarded as a promising the energy conversion device from chemical energy of fuel, because of numerous advantages, such as high energy conversion efficiency, multi fuel capability, and no emission of pollutants [1]. Co-based perovskite oxides have spotlighted. For the cathode materials of SOFCs due to low over-potential for the oxygen reduction reaction (ORR), thus resulting in high performance of SOFCs [2]. However, the large dissimilarity of thermal expansion coefficient (TEC) between Co-based perovskites and typical yttria-stabilized zirconia (YSZ) and samarium-doped ceria (SDC) electrolytes result in degrading of long-term durability of SOFCs. The TECs’ of Co-based perovskite oxides are but the general electrolyte, such as YSZ’s TEC is and, indicating a huge difference between them [3].
Meanwhile, lanthanum nickelate, Lan+1NinO3n+1, may have high thermal stability than Co-based perovskites, because the TEC of Lan+1NinO3n+1 is , similar to the YSZ electrolyte [4]. In this work, hence anode-supported cells are fabricated with SDC electrolytes, Ni-cermet anode, and lanthanum nickelate cathode. To investigate the performance and durability of cathode materials, I-V measurements and load cycling testing methods are used to check the performance and durability of cells. The electrochemical impedance spectroscopy measurements are also performed for the electrochemical analysis. In addition, various physicochemical analysis tools are used, such as SEM, TEM, and XRD as the postmortem analysis [5].
References
[1] K.T. Lee, E.D. Wachsman, Science 334 (2011) 935.
[2] E. Boehm, J.-C. Grenier, Solid State Sciences 5 (2003) 973.
[3] S. Pang, X. Xi, J. Power Sources 326 (2016) 176.
[4] R.K. Sharma, E. Djurado, J. Power Sources 325 (2016) 337.
[5] T.H Lee, J.-Y. Park. J. Power Sources 331 (2016) 495
Keywords : Solid oxide fuel cells; Lanthanum nickelate; Thermal Expansion Coefficient; Durability

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park)