bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Interaction of Ni Anode with Gd-Doped CeO2 Studied By Adsorbed Species with Infrared Spectroscopy
Authors: Kubota Jun 
Published: February 2020

The interaction between Ni anode and Gd-doped CeO2 (GDC) has been studied by adsorbed CO as probe molecules using infrared spectroscopy. Ni/GDC cermet anodes are frequently used in solid oxide fuel cells (SOFC). The properties of Ni anode, such as carbon deposition with the use of fuel of methane, is known to be strongly affected by oxide electrolytes. The Ni and GDC particles are considered to be in micrometer scale each other, however the GDC particles interact to most reaction sites of Ni surfaces. The structure of Ni/GDC is first examined by Auger micro-analysis. It was found that the Ni particles in micrometer scale is mostly covered with GDC thin layer after the treatment of H2 reduction. Therefore, broadly and thinly migrated GDC on the Ni surfaces was proposed to be the essence of the interaction. Infrared spectra of CO adsorbed on Ni sites are known to reflect the nature of Ni sites. The adsorbed CO on Ni sites of Ni/GDC was found to have obvious low-frequency shift from those of Ni/Y:ZrO2 and Ni/Al2O3, indicating that GDC species were strongly interacted with the most Ni sites. The properties of interaction between Ni anode and GDC after carbon deposition will be discussed.

Figure 1
Assessing Doping Effects on Surface Chemical Stability By in Situ AP-Xps in Barium Perovskites, BaCexZr0.9-XY0.1O2.95 (x = 0.9 ; 0.2 ; 0)
Authors: Jarry Angelique , Ricote Sandrine , Geller Aaron , Zhang Xiaohang , Pellegrinelli Christopher , Takeuchi Ichiro , Wachsman Eric D. , Eichhorn Bryan W. , Crumlin Ethan J 
Published: February 2020

The two major proton-conducting solid oxide fuel cell (PCFC) performance limitations are the long-term stability as well as the concentration and mobility of proton defects in the electrolyte. The main electrolyte candidates are perovskite type, in particular, yttrium doped barium Ba(Zr/Ce/Y)O3-s materials. However the poor grain boundary conductivity of BaZr0.9Y0.1O2.95 (BZY) and the lack of chemical stability of BaCe0.9Y0.1O2.95 (BCY) impede their application. The first issue can be addressed by the development of grain boundary-free thin films which exhibit conductivity level up to three orders of magnitude higher than standard sintered pellets.[1] A solid solution of BZY and BCY, BaCe0.2Zr0.7Y0.1O2.95 (BCZY), demonstrates further optimized conductivity levels and chemical stability.[2, 3] However, due to the low concentration of protons and surface gas sensitivity of these materials, detailed knowledge on the chemical interaction between elements from oxide host lattice and fuel cell environment is still lacking, hindering PCFC development.
In this work, we developed BaCexZr0.9-xY0.1O2.95 epitaxial thin films and characterized their performance with electrochemical impedance spectroscopy. We investigated the doping effect on surface chemistry by using Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS) in fuel cell environments (100 mtorr of H2O, H2, O2 or CO2) at operating temperature (>400°C). Upon applying water partial pressure, changes in the O 1s and Y 3d core level spectra were observed with a clear dopant dependency. These results indicate the formation of degradation products at the surface. The correlation between surface activity, composition, chemical stability, and conductivity level as well as associated new insights into the dopant effect on hydration and degradation mechanisms will be discussed.

References

[1] D. Pergolesi, E. Fabbri, A. D’Epifanio, E. Di Bartolomeo, A. Tebano, S. Sanna, S. Licoccia, G. Balestrino, E. Traversa, Nat Mater
9 (2010) (10) 846.
[2] S. Ricote, N. Bonanos, A. Manerbino, N.P. Sullivan, W.G. Coors, Journal of Materials Chemistry A
2 (2014) (38) 16107.t
[3] S. Ricote, N. Bonanos, H.J. Wang, R. Haugsrud, Solid State Ionics
185 (2011) (1) 11.

Acknowledgement

This work was supported by the Office of Naval Research (ONR) and The Advanced Light Source (ALS) funded by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences under award DESC0001160 and Contract No. DE-AC02-05CH11231 repectively.
Correlating Cathode/Electrolyte Interface Characteristics to SOFC Performance
Authors: Szász Julian , Wankmüller Florian , Joos Jochen , Wilde Virginia , Störmer Heike , Gerthsen Dagmar , Ivers-Tiffée Ellen 
Published: February 2020

Correlating chemical composition and microstructure characteristics of both electrode/electrolyte interfaces to the performance of a solid oxide fuel cell (SOFC) is of fundamental importance for further improvement [1]. Focused ion beam / scanning electron microscopy (FIB/SEM) reconstruction is one of the most advanced techniques for the quantitative assessment of microstructure characteristics of primary material phases. Progress was recently made in approaching also the local distribution of secondary phases and impurities by combining FIB/SEM with TEM/EDXS elemental analysis (transmission electron microscopy / energy dispersive x-ray spectroscopy) [2]. Applying this method to the cathode/electrolyte interface; LSCF cathode (La1-xSrxCo1-yFeyO3-
δ) / GDC barrier layer (Gd-doped Ceria) / YSZ electrolyte (Y2O3 stabilized ZrO2) reveals important findings:
Formation of the secondary phase SrZrO3 (SZO) dominates interface resistance and cell performance, depending on volume and local distribution (Fig. 1 and 2) [2,3]. This is confirmed by in-situ impedance and performance measurements of symmetrical and full cells (Fig. 1). A model is introduced, which simulates the locally resolved contribution of a secondary phase like SZO to the charge transfer reaction and GDC/YSZ interdiffusion (ID) to the ion diffusion at a heterogeneous cathode/electrolyte interface. It will be demonstrated, that the barrier layer functionality is determined by the applied sintering temperature. Functionality is achieved by a custom-tailored thick ID layer at high sintering temperatures. In contrast are low GDC sintering temperatures; then functionality fails, and a continuous SZO layer forms (Fig. 2 (a)) which increases the cathode overpotential over two orders of magnitude.
The results of this contribution are fundamental for understanding the microstructure characteristics of secondary phases and their correlation to SOFC performance. They convey intuitive knowledge to fabricate high performance cathode/electrolyte interfaces for individual cell concepts.

References

[1] J. Joos, T. Carraro, A. Weber, E. Ivers-Tiffée, J. Power Sources, 196 (17), (2011) 7302-7307.
[2] H. Yokokawa, N. Sakai, T. Horita, K. Yamaji, M. E. Brito, H. Kishimoto, J. Alloys Compd., 452 (1), (2008) 41–47.
[3] J. Szász, F. Wankmüller, V. Wilde, H. Störmer, D. Gerthsen, E. Ivers-Tiffée, ECS Trans., 66 (2), (2015) 79–87.

Figure 1
Effect of Fe-Doping on Oxygen Anion Diffusion in PrBaCo2-xFexO5+δ Double Perovskite Electrodes for Solid Oxide Fuel Cells
Authors: Anjum Uzma , Agarwal Manish , Khan Tuhin Suvra , Haider M Ali 
Published: February 2020

The Molecular dynamics simulations on PrBaCo2O5+δ (PBCO) was carried out to calculated the oxygen anion diffusion coefficient in the a-b direction, which was measured to be 3 x 10-8 cm2s-1 at 873 K and the diffusion coefficient was observed to be higher than the c plane (D=8x10-9 cm2s-1 at 873K) as shown in inset of Figure 1a.The electrochemical performance was observed to correlate with the oxygen diffusion coefficient. The diffusivity in PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) (1.18 x 10-7cm2s-1) was calculated to be higher by an order of magnitude as compared to PBCO (3x10-8 cm2s-1 at 873 K, Figure 1a). Dense thin-film of electrodes of PBSCF (2 µm thick) with <500 nm grain sizes measured to give a polarization resistance of 7.21 Ω cm2 at 873 K, (Figure 1b), which was ascribed to the bulk-diffusion in the electrode. In parallel, oxygen vacancy formation in the Gd plane (Eov= 98.4 kJ/mol) of GdBaCo2O5+δ (GBCO) was measured to be lower than that of Ba plane (Eov=266.3 kJ/mol), therefore; vacancies were observed to be concentrated in the Gd plane. The surface energy of the Ba plane was measured to be minimum ϒ =7.2 kJ/mol, which makes it the most exposed surface, while it is least diffusive for oxygen anions. Therefore, larger size bulk microstructures of GBCO were measured to give lesser than expected oxygen anion diffusivity (D=6.04x10-10cm2s-1). GBCO particles of reduced size are expected to expose higher energetic Gd plane, which may enhance diffusivity. The particle size of GBCO was reduced to 20 nm using a bio-milling approach, wherein the chemically synthesized particles were subjected to fungus Saccharomyces Cerevisiae, for 72 hrs of fermentation (Figure 1c). The electrochemical performance of the bio-milled nanoparticles electrode was improved by 20% as compared to bulk electrode of GBCO particles (Figure 1c). MD simulation on a GBCO nanoparticle showed, the diffusion in nanoparticles to represent two distinct regimes; one corresponding to the surface and other the bulk. The stability of nanoparticles were validated by calculating the root mean square deviation (RMSD) of atomic positions in MD simulations. The thickness (20A0) of diffusive surface shell regime was observed to be particle size independent, while the thickness of the diffusive core regime varies with the size of nanoparticle as shown Figure 1d. The diffusivity of the shell regime (D=3.61x10-9 cm2 s-1) was calculated higher than of the core (D=5.07x10-10 cm2 s-1 at 1073K). Thus, nanoparticles showed improved electrochemical performance as compared to the bulk electrode.

Figure 1
(Invited) H. Russell Kunz: A Perspective on His Early Career
Authors: Kunz Roderick 
Published: February 2020

Fuel cell research at the Power Systems Group at Pratt & Whitney Aircraft rapidly expanded in 1962 when NASA awarded a contract to produce the fuel cells for the Apollo space program. At the time, Russ Kunz had already been at Pratt & Whitney for nine years, having been hired in 1953 straight out of college. Upon joining Pratt & Whitney, Russ was assigned to a team that had before his arrival been working to develop an advanced axial-flow turbojet engine, an activity with national security implications. This engine was to be used in two aircraft of strategic importance, an eight-engine long-range bomber and the world's first supersonic interceptor. The engine received the Air Force designation J57 and became the power plant used in both the B-52 Stratofortress bomber and the F-100 Super Sabre fighter, the latter of which became the first jet-powered aircraft able to sustain supersonic speed at low altitude and which set performance records that held for 10+ years. During his first nine years at Pratt & Whitney, Russ made significant contributions to the J57 that enabled subsequent versions to increasingly provide greater performance.
Russ' involvement with the jet engine program ended when, in 1964, Pratt & Whitney moved its Power Systems Group from East Hartford, CT twelve miles north to a smaller facility in South Windsor, CT and Russ moved with it. It was at this facility where the fuel cells for every Apollo mission from 1966 to 1972 were produced. Work there continued with the transition to the Space Shuttle program from 1981 to 2011. During this period, Russ played a leading technical role.
Although the fuel cell community may now remember Russ' for his more recent contributions, it was his earlier work on high-performance jet engines and power systems for the space program that embodied the technical challenges of a time when the future of aerospace technology was still being defined. This presentation will provide a brief overview of the contributions Russ made in his early career, within the context of the times, and the influence this work had on his family.
(Invited) High-Performance PGM-Free Electrocatalysts for the Polymer Electrolyte Fuel Cell Cathode
Authors: Yin Xi , Chung Hoon T , Lin Ling , Purdy Geraldine M , Martinez Ulises , Zelenay Piotr 
Published: February 2020

The activity of oxygen reduction reaction (ORR) catalysts often determine performance of polymer electrolyte fuel cells (PEFCs) as measured by their power output, open circuit voltage, and fuel conversion efficiency. Currently, Pt-nanoparticle catalysts, either supported on high surface-area carbons or prepared in a form of contiguous thin layer on conductive or non-conductive supports, represent the state of the art in ORR electrocatalysis at the PEFC cathode. However, the high and variable price and scarceness of Pt have limited its widespread implementation in the -temperature fuel cells to date, especially in automotive transportation. Under these circumstances, platinum group metal-free (PGM-free) ORR catalysts have received growing attention in recent years as a possible replacement for Pt-based formulations. The progress achieved since the development of the first nature-inspired electrocatalysts of oxygen reduction in the seminal work by Jasinski in the 1960s (Nature 201, 1212, 1964), which mostly happened through the broad implementation of the high-temperature synthesis approach, makes replacement of Pt in ORR electrocatalysts with earth-abundant elements, such as Fe, Co, N, and C, a realistic possibility.
In this this presentation, we will summarize recent progress in research targeting development of high-performance PGM-free catalysts for oxygen reduction reaction (ORR) at Los Alamos National Laboratory. Two approaches will be discussed in a greater detail: (i) the approach involving fine-tuning of the catalyst porosity and surface area using pore-forming compounds and (ii) the method specifically focusing on the development of atomically dispersed transition metal moieties and avoiding the formation of transition metal-rich nanoparticles during the heat treatment of catalyst precursors. We will demonstrate the impact that porosity/surface area optimization, through the use of either pore formers (cyanamide, ZnCl2) precursor templating (metal organic frameworks) or both, can have on the fuel cell performance of PGM-free catalysts. We will also show how modifications to the electrode structure through the change in the ionomer content and ionomer equivalent weight can lead to substantial improvements in the fuel cell performance at both low- and high current densities (aerial power density of more than 0.50 W/cm2 in H2-air testing at 80°C).
Finally, we will recapitulate the challenges still facing PGM-free research that, in spite of all the progress achieved in recent years, is yet to produce materials capable of competing with the incumbent Pt-based catalysts in terms of oxygen reduction activity, performance durability, and cost (specifically, when extended to the overall cost of a fuel cell stack).

Acknowledgement

Financial support for this research by DOE-EERE through Fuel Cell Technologies Office is gratefully acknowledged.
(Invited) Understanding Fuel Cell Materials Degradation through the Use of Advanced Microscopy Methods
Authors: More Karren L. 
Published: February 2020

Polymer electrolyte membrane fuel cell (PEMFC) performance and materials degradation, particularly associated with the cathode catalyst layer, can be directly attributed to the stability and durability, as well as the uniformity/homogeneity, of the individual material constituents comprising the membrane electrode assemblies (MEAs) e.g., electrocatalyst, catalyst support, and ionomer films, and the interfaces formed between these constituents. The structural and chemical homogeneity of the constituent materials and their interfaces within catalyst layers can be quantified via advanced electron microscopy methods. Ultimately, this microstructural evidence can be directly correlated with materials-specific degradation mechanisms that contribute to PEMFC performance loss, and can be used to identify potential processing variables that will improve the microstructure and compositional homogeneity within the electrode structure and enhance MEA durability and stability during operation. Research efforts at Oak Ridge National Laboratory are focused on the high-resolution microstructural and microchemical characterization of MEAs fabricated using different electocatalysts (Pt-based) and catalyst loadings, carbon-based support materials, and ionomer solutions, as well as the same MEAs subjected to accelerated stress tests (ASTs) designed to degrade specific MEA components. High-resolution analytical microscopy methods are used to directly image and map the distribution and chemistry of the various phases within catalyst layers, both on the micrometer-scale for assessing electrode through-thickness homogeneity and at the sub-Å-level to interrogate the individual constituents and the various interfaces formed. This presentation will focus on the application of advanced microscopy methods used to evaluate cathode catalyst layers before and after ASTs and how such methods can provide insight towards improved electrode design, durability, and performance.
________________________________________________________________________
Research sponsored by (1) the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy and (2) Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility.
(Invited) Measuring Transport in Polymer Electrolyte Membranes
Authors: Mittelsteadt Cortney K 
Published: February 2020

It is commonly agreed upon that the transport properties of PEMs have a great effect on fuel cell performance. These include proton conductivity, ion mobility, reactive and inert gas solubility and diffusivity, water transport due to concentration and pressure gradients, and electroosmotic drag. Despite this there are widely different methods used to obtain these properties, and even greater differences in reported numbers.
Much of the difficulty in reaching agreement on transport numbers lies in the difficulty of defining the polymers themselves. Small changes in temperature or relative humidity can lead to large changes in transport properties, especially conductivity and water transport. The membranes water content is also a strong function of these conditions, and therefore the dimension of the polymer is also changing. Compounding difficulties is the fact that the thermal and hygral history greatly affect structure on the nano scale, and also have a strong impact on these properties.
This talk looks at the different transport phenomena in PEMs, there relative influence on fuel cell performance, methods that have been used to measure them, and common errors that are made. It also focuses on some unsolved questions, or areas of open debate in the fuel cell community, such as does diffusivity differ when a membrane is hydrating and expanding, compared to when it is dehydrating or contracting? Can the electroosmotic drag coefficient decrease below unity? Is transport greatly affected by ionomer thickness?
(Invited) Duramat - a Systems Driven Approach to Improving Module Material Durability in the Energy Materials Network
Authors: Barnes Teresa M. , Olson Dana , Gordon Margaret , Ginley David , Toney Michael F , Jain Anubhav , Schunk Randy , Kurtz Sarah 
Published: February 2020

The Durable Module Materials Consortium, or DuraMat, is a consortium led by the National Renewable Energy Laboratory (NREL), in partnership with Sandia National Laboratories, Lawrence Berkeley National Laboratory, and SLAC National Accelerator Laboratory, that is intended to accelerate the development of module materials for photovoltaics (PV) and lower the cost of electricity generated by solar power.
The overarching goal of DuraMat is to discover, develop, de-risk, and enable the rapid commercialization of new materials and designs for photovoltaic (PV) modules that can improve performance and lifetime with the goal of enabling a solar levelized cost of electricity (LCOE) of less than $0.03 per kilowatt hour. As part of the Energy Materials Network (EMN), DuraMat brings together the best of the national lab and university research infrastructure in active collaboration with the PV and supply-chain industries to achieve this goal. DuraMat provides a unique opportunity to employ the Materials Genome Initiative methodology in the EMN framework in order to accelerate advances in materials and module designs and increase US competitiveness.
(Invited) Benchmarking and Round Robin Testing for Polymer Electrolyte Membrane Water Electrolysis
Authors: Carmo Marcelo , Bender Guido , Smolinka Tom , Gago Aldo Saul , Danilovic Nemanja , Müller Martin , Ganci Fabrizio , Alia Shaun M , Fallisch Arne , Lettenmeier Philipp , Friedrich K. Andreas , Ayers Katherine E , Pivovar Bryan S , Mergel Jürgen , Stolten Detlef 
Published: February 2020

The development of water electrolysis based on polymer electrolyte membrane (PEM) technology is of high importance for the advancement of hydrogen based energy solutions. To facilitate rapid improvement in material performance and durability, domestic and international collaboration is essential. A successful exchange however requires a meaningful comparison of data across laboratories. The establishment of such a meaningful comparison is a challenging undertaking that requires attention to detail with respect to operating conditions, protocols, test hardware, and instrument calibration. Members of the Annex 30 Electrolysis working group (The IEA Technology Collaboration Programme on Advanced Fuel Cells), focusing on the progress of water electrolysis and the alignment of test procedures on an international basis, have recently started an effort to address these challenges for PEM water electrolysis cells.
This presentation will focus on the challenges encountered and solutions found when developing benchmarking procedures and performing round robin testing across laboratories. The effort targets to harmonize testing procedures and enable benchmarking of PEM water electrolysis performance via in-situ performance testing using single cells.
(Keynote) Electroreduction of Nitrocyclopropanes and Nitrophenyl Cyclopropanes: Mechanism of Cleavage of the Radical Anion
Authors: Lessard Jean , Fry Albert J. 
Published: February 2020

There are three possible mechanisms of cleavage of a nitrocyclopropane radical anion 1•‾, mechanisms A (homolytic cleavage to a cyclopropyl radical 2• and a nitrite anion), B (homolytic cleavage to a distonic radical anion 3•‾ ), and C (heterolytic cleavage to a distonic radical anion 4•‾ [1]. With the models synthesized so far (Y = Z= alkyl, H = COOCH3), only products of mechanism A have been observed [1]. On the other hand, only two cleavage mechanisms are possible for a nitrophenyl cyclopropane radical anion 5•‾, mechanisms D (homolytic cleavage to the distonic radical anion 6•‾ ) and E (heterolytic cleavage to the distonic radical anion 7•‾ ) [1]. The isolation and characterization of the products resulting from the cleavage of the nitrophenyl radical anion 5•‾ do not allow to distinguish between the two cleavage mechanisms D (homolytic cleavage) and E (heterolytic cleavage) leading to the distonic radical anions 6•‾ and 7•‾ respectively.
To shed light on the mechanisms of cleavage of those radical anions, density functional (DFT) quantum chemical calculations were carried out on species 1-3 (B3LYP 6-31+G(d), including solvation energies in acetonitrile computed using the polarizable continuum method. The results clearly favor mechanism B and species 3 over mechanisms A and C for the decomposition of anion radicals 1•‾ whenZ = Y = alkyl and X = H.

[1] F. Couture-Martin, A. Sardashti, C. Cristea, J.M. Chapuzet, J. Lessard, ECS Transactions, 2008, 13, 13-19.

Figure 1