bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Electrode Engineering of Solid-Oxide Electrochemical Cells at National Energy Technology Laboratory
Authors: Hackett Gregory A , Lee Shiwoo , Abernathy Harry , Kalapos Thomas , Na Beom-Tak , Muhoza Sixbert P , Duffy Jack , Gross Michael D , Brinkman Kyle S 
Published: February 2020

The National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Team performs fundamental SOFC technology evaluation, enhances existing SOFC technology, and develops advanced SOFC concepts in support of the U.S. Department of Energy SOFC Program. Program targets include a reduction in performance degradation to 0.2% per 1000 hours and a system cost of $900 per kilowatt. Research and development is essential to meet these targets. Research efforts are broadly focused on an investigation of cell and stack degradation, electrode engineering, grid integration challenges, and system analysis. The research approach is targeted to specifically address SOFC program technology development goals, especially regarding reducing stack costs, increasing cell efficiency, and increasing cell reliability and robustness. The goal of these efforts is to transfer technology that facilitates commercial acceptance of SOFC technology. This is accomplished through close collaboration with SOFC commercial developers, national laboratories, and academic institutions.
NETL system-level analysis has shown that a critical consideration for reducing the cost of SOFC technology is the enhancement of electrode performance and longevity through materials and microstructure engineering. Within this scope is the special consideration of cell production costs and operating temperature. Specifically, at NETL, nano-electrocatalyst infiltrations have been a successful operation by scaling up the patented technology to a commercially-relevant scale, partnering with industrial manufacturers. The effort has continued to the construction of a scaffold microstructure that is optimized for surface modification and the development of gel-derived high surface area electrodes. Electrode materials selection has been made through a computational approach that uses electronic structure and energetics in conjunction with thermodynamics and statistical physics, identifying multicomponent oxides with high oxygen reduction reaction activity and stability. Highly reliable electrical conductivity relaxation analysis confirmed the predicted electrode materials’ superior surface exchange property when compared to the state-of-the-art lanthanum strontium cobalt ferrite. The developed electrode engineering techniques have been applied for reversible solid-oxide cell operation as well as single mode solid-oxide cells to stabilize electrodes while maintaining improved performance and longevity.
(Invited) Sensitized "Thermal" Cell
Authors: Matsushita Sachiko 
Published: February 2020

Efficient and low-cost thermal energy-harvesting systems are needed to solve the global energy crisis. If we were able to extract electrical energy directly from the geothermal sources, then the night would be safe regardless of developed or underdeveloped countries; there is no problem in the treatment of radiation waste. Heat, called low quality energy, would become a great renewable energy.
As such a dream cell, we suggested sensitized thermal cells (STCs), that is a new green power generation system operate by heating without a cooling temperature part (Japanese Patent Application No. 2015-175037). The structure of STC imitates the dye-sensitized solar cells (DSSCs).
In DSSCs, electrons in dyes are photoexcited by light irradiation, and the excited electrons are injected into the conduction band of an electron transport material. The transported electrons reduced oxidant ions in electrolyte, and the reductant ions were oxidized by the photoexcited holes, and we can get photo-excited current. If thermally excited electrons in the semiconductor can generate the ion redox reactions, a novel heat-to-electron conversion system functioned without a temperature difference, named a “sensitized thermal cell”, can be obtained.
This concept was firstly demonstrated using β-FeSi2 as the semiconductor material, n-Si as the electron transfer material, and a cupper ion conductor (CUSICON) as the electrolyte (1). The cell exhibited an open circuit voltage of 0.67 V and a short circuit current of 9.1 μA cm-3 at 600 °C. The acquisition voltage continuously maintained this value for at least 35 h in nitrogen. The redox reactions of the electrolyte ions due to thermal excited charge carriers were demonstrated using XPS.
To convince the STC's principle, we also focused on an organic perovskite. This material has been used in a sensitized solar cell, and recent calculations show that it can generate several thermally excited charges at temperatures over 60 °C. Thus, if this perovskite cell can generate electric power with both light irradiation and thermal excitation, the STC concept would be perfectly proven, and the device succeeds thanks to the careful analysis of the perovskite’s unstableness (2). The battery characteristics of the cell were convinced both light irradiation and thermal excitation above the phase transition temperature of the organic perovskite. And very recently, it was revelaed that Ag2S also could act as the sensitizer both by light and heat (3). These results clearly prove the concept of an STC.
In this presentation, we will also report the latest results of the STCs, especially focused on the termination process.
[References]
(1) S. Matsushita, A. Tsuruoka, E. Kobayashi, T. Isobe and A. Nakajima, Mater. Horiz., 2017, 4, 649–656.
(2) S. Matsushita, S. Sugawara, T. Isobe and A. Nakajima, ACS Appl. Energy Mater., 2019, 2, 13-18.
(3) Y. Inagawa, T. Isobe, A. Nakajima, and S. Matsushita, J. Phys. Chem. C, in press. DOI: 10.1021/acs.jpcc.9b01922
Photoelectrochemical Applications of SrNbO2n Thin Films Synthesized Via a Two-Step Process at Reduced Temperatures
Authors: Heinselman Karen , Hwang Shinjae , Laursen Anders B. , Talley Kevin , Young James L. , Dismukes Gerard Charles , Garfunkel Eric , Zakutayev Andriy 
Published: February 2020

Oxynitride materials often exhibit a perovskite structure in which the oxygen and nitrogen occupy the same lattice sites. Such oxynitride perovskites, for example SrNbO2N with a favorable bandgap of 1.8 eV for tandems, are studied as photoanodes for photoelectrochemical (PEC) water splitting applications. These photoanodes are an essential component to the OER side of the water splitting cell. In literature, SrNbO2N PEC electrodes are often prepared using ammonolysis of deposited Sr2Nb2O7 oxide at high temperatures. To transform Sr2Nb2O7 into SrNbO2N, the ammonolysis temperature has to reach over 900 °C for the time period of minutes to hours. This often leads to intermixing and reactions between the layers in the thin film device stack.
In this presentation, PEC measurements of photocurrent are presented for SrNbO2N on n-Si in ferro/ferricyanide, at varying thicknesses and Sr:Nb ratios. For the deposition of these films, we show a two-step low-temperature synthesis approach to SrNbO2N on Si for tandem PEC applications. In the first step, combinatorial RF sputtering (sometimes with a nitrogen plasma cracker) is used to deposit Sr1+yNb1-yO2-xN1+x at ambient temperature with varying Sr:Nb and O:N ratios. In the second step, these films are annealed in a nitrogen atmosphere using Rapid Thermal Annealing (RTA). We surveyed a series of temperatures and times to determine the minimum temperatures needed to obtain highly crystalline SrNbO2N for PEC applications without reaction with the Si substrate. The resulting film morphology, crystalline structure, and other characterization across the combinatorial spread was characterized. Photocurrent was observed in these materials over a range of varying thicknesses and compositions using a solar simulator and a standard 3-electrode setup.
(Invited) Functional Defects By Design—a High-Throughput Approach to Energy Materials Discovery
Authors: Ganesh Panchapakesan 
Published: February 2020

Defects and impurities introduce localized heterogeneities in solids and decisively control the behavior of a wide range of energy technologies. Fuel cell materials, especially proton conducting fuel cells, are a quintessential example in this regard. Designing and developing solid oxide materials that can selectively transport protons will enable us to develop the next generation proton conducting solid oxide fuel cells. Protons require less activation energy compared to oxygen ions which results in a lower operating temperature, higher operating efficiency and better material reliability. In this work [1,2,3,4] we focus obtaining fundamental insights on how properties of host material structure along with dopants, disorder and strain influences proton transport properties in solid oxides by coupling high-throughput computations with functional imaging, neutron spectroscopy and transport measurements.
We initially focus on the perovskite family of compounds (such as doped BaZrO3). We benchmark our calculations against a wide range of experimental measurements such as kelvin probe force microscopy (KPFM), inelastic neutron scattering (INS) and atom probe tomography (APT). To obtain better insights on why certain cubic perovskite/dopant combinations are better at conducting protons compared to others, we developed a high-throughput framework to perform ab initio calculations. The high-throughput framework can scale massively to tens of thousands of nodes to fully exploit the computational capability of the Oak Ridge Leadership Computing facility. We employ this approach to calculate proton transport properties in several cubic perovskite materials with different host atoms and dopants. The results obtained from these calculations enables us to obtain better insights on how material structure – such as atomic properties (electronegativity, ionic radius) and lattice properties (sub-lattice distortion) influences proton transport. The results obtained from this high-throughput analysis is being employed to develop a machine learning framework to predict structure-property correlations on a larger set of perovskites materials. Finally, we explore the role of disorder on proton transport by studying for example fluorite based lanthanum tungstate materials.
[1] “Defect Genome of Cubic Perovskites for Fuel Cell Applications”, Journal of Physical Chemistry C, 121, 26637 (2017)
[2] “The Influence of Local Distortions on Proton Mobility in Acceptor Doped Perovskites”, Chemistry of Materials, 2018, 30 (15), pp 4919–4925
[3]“The Influence of the Local Structure on Proton Transport in a Solid Oxide Proton Conductor La0.8Ba1.2GaO3.9”, J. Mat. Chem. A, 5, 15507 (2017)
[4] “Influence of Non-Stoichiometry on Proton Conductivity in Thin Film Yttrium-doped Barium Zirconate”, ACS Appl. Mater. Interfaces, 2018, 10 (5), pp 4816–4823
(Invited) Electrocat: Expediting PGM-Free Fuel Cell Catalyst and Electrode Development
Authors: Papageorgopoulos Dimitrios C , Thompson Simon T. , Myers Deborah J. , More Karren L. , Neyerlin K C , Zelenay Piotr 
Published: February 2020

The development of platinum group metal-free (PGM)-free catalysts with comparable performance and durability to low- PGM catalysts would hasten the cost competitiveness of fuel cells with alternative technologies. Therefore, addressing electrocatalyst development represents the most pressing technical barrier in fuel cell deployment and in meeting the ultimate U.S. Department of Energy (DOE) automotive fuel cell system cost target of $30/kW.
ElectroCat (The Electrocatalysis Consortium), like other DOE Energy Materials Network (EMN) consortia, aligns research and development (R&D) activities at national laboratories and, through DOE-funded projects, facilitates access of academic and industry partners to the world-class capabilities and expertise at the national labs. These capabilities, such as (1) catalyst synthesis (including in particular high-throughput methods), (2) advanced characterization expertise, and (3) quantum chemical modeling address the salient knowledge gaps in PGM-free catalyst development: ascertaining the structure-function relationship, increasing active site density, improving electrode structure to maximize active site utilization and mitigate mass transport limitations, and improving durability. In the near-term, the consortium will work to develop PGM-free catalysts and electrodes to meet the 2025 DOE current density technical target of 0.044 A/cm2 at 0.9 VIR-free, analogous to the goal for low-PGM catalysts. In 2018, ElectroCat R&D efforts increased initial activity by 68% compared to the 2016 baseline of 16 mA/cm2. The presentation will highlight current R&D advancements, core national lab experimental and computational capabilities, as well as high-throughput and machine-learning approaches to expedite the development of PGM-free catalysts and electrodes.
(Invited) SCAN Meta-GGA: An Accurate, Efficient, and Physically Sound Density Functional for Materials Discovery and Design
Authors: Sun Jianwei 
Published: February 2020

The accuracy and computational efficiency of the widely used Kohn-Sham density functional theory (DFT) are limited by the approximation to its exchange-correlation energy Exc. The earliest local density approximation (LDA) overestimates the strengths of all bonds near equilibrium (even the vdW bonds). By adding the electron density gradient to model Exc, generalized gradient approximations (GGAs) generally soften the bonds to give robust and overall more accurate descriptions, except for the vdW interaction which is largely lost. Further improvement for covalent, ionic, and hydrogen bonds can be obtained by the computationally more expensive hybrid GGAs, which mix GGAs with the nonlocal exact exchange. Meta-GGAs are still semilocal in computation and thus efficient. Compared to GGAs, they add the kinetic energy density that enables them to recognize and accordingly treat different bonds, which no LDA or GGA can [2]. In this talk, I will present an advance in DFT, the recently developed non-empirical strongly constrained and appropriately normed (SCAN) meta-GGA [1]. SCAN predicts accurate geometries and energies of diversely-bonded molecules and materials (including covalent, metallic, ionic, hydrogen, and van der Waals bonds), significantly improving over its predecessors, the GGAs that dominate materials computation, at comparable efficiency [2]. SCAN’s excellent performance on formation enthalpies and ground structure predictions, critical for materials discovery and design, will be highlighted [3]. I will further explain how SCAN was constructed [1], why it can improve over GGAs [2], and where it should fail [4]. At the end, efforts to improve SCAN via nonlocal corrections will be discussed.
[1] J. Sun, A. Ruzsinszky, and J.P. Perdew, Strongly constrained and appropriately normed semilocal density functional, PRL
115, 036402 (2015).
[2] J. Sun, R.C. Remsing, Y. Zhang, Z. Sun, A. Ruzsinszky, H. Peng, Z. Yang, A. Paul, U. Waghmare, X. Wu, M.L. Klein, and J.P. Perdew, Accurate First-principles structures and energies of diversely-bonded systems from an efficient density functional, Nat. Chem.
8, 831 (2016).
[3] Y. Zhang, D.A. Kitchaev, J. Yang, T. Chen, S.T. Dacek, R.A. Sarmiento-Perez, M.A.L. Margues, H. Peng, G. Ceder, J.P. Perdew, and J. Sun, Efficient first-principles prediction of solid stability: Towards chemical accuracy, NPJ Computational Materials
4, 9 (2018).
[4] H. Peng, Z. Yang, J.P. Perdew, and J. Sun, Versatile van der Waals density functional based on a meta-generalized gradient approximation, PRX
6, 041005 (2016).
(Invited) Mn4+ r-Line Emission Intensity: The Ways of Its Enhancement
Authors: Brik Mikhail G. , Srivastava Alok M 
Published: February 2020

Mn4+-based red phosphors are excellent materials to be used for making white LEDs with warm white light. They can be excited by the blue or ultraviolet light to produce red photoluminescence (PL), which is due to the parity and spin-forbidden 2Eg→4A2g transition. However, in many host materials, the intensity of the 2Eg→4A2g zero-phonon line (R-line) is very weak due to the presence of the inversion center of the crystallographic site occupied by the manganese ions. As a result, the red-shifted Stokes components dominate in the emission spectra of such hosts, but this leads to the decreased overlap of the PL spectra with human eye sensitivity curve and decreased intensity of the phosphor (lower lumen/Watt value). Therefore, finding the recipes of enhancement of the R-line intensity and production of brighter phosphors is an important scientific and technological task.
In the present work we establish the key parameters responsible for the energy and the intensity of the Mn4+ R-line. Thorough consideration and analysis of the optical spectra for a large number of the Mn4+-based phosphors allowed to draw the following conclusions:

The energetic position of the R-line is determined by the “Mn4+-ligand” bonding covalence. Most phosphors for the solid state lighting can be conditionally divided into fluorides and oxides (where the fluorine or oxygen ions are the Mn4+ nearest neighbors, respectively). In ionic fluorides, the Mn-F bonding covalence is weak, which shifts the R-line to higher energies, with the emission wavelength at about 620 nm. In covalent oxides, the stronger Mn-O bonding covalence lowers the energy of the 2Eg state, moving the emission to about 650 nm.

In the host crystals, where the Mn4+ ions are located at the sites without inversion center, the R-line intensity is higher compared with the crystals possessing inversion symmetry at the Mn4+ Absence of the inversion center relaxes the parity section rule, which enhances the R-line intensity. As a result, the phosphor luminosity is increased considerably. The inversion center can be removed by cation co-doping, when different cations in the second coordination sphere around the Mn4+ ion remove the inversion center.

As an example, a figure below shows the PL spectra of K2SiF6:Mn4+ and NaKSiF6:Mn4+. In the former case the ideal MnF6 octahedron with the inversion center does not allow for high R-line intensity. It the latter case structural disorder and mixed occupation at the K/Na site results in the presence of different cations in the second coordination sphere. As a result, the intensity of the R-line is increased by several times.
Therefore, to get the phosphors with increased luminosity one has to focus on the host materials without inversion center at the dopant sites. If, however, the inversion symmetry exists, it should be broken by additional co-doping that would produce structural disorder around the dopant.

Figure 1
Single Cell Electrochemistry – Uptake of Bioinorganic Silver-Based Drugs
Authors: Sidambaram Prabhakar , Colleran John 
Published: February 2020

Heterogeneity in a cell population is a universal phenomenon in all biological systems including whole tissues, and cell cultures.[1] Intra-tumour heterogeneity has been widely reported for decades from morphological perspectives, whereas phenotypic and genotypic heterogeneity has also been detected.[2] DNA platination is widely assumed as the central mode of action for most platinum anti-cancer drugs. This generalisation on the mode of action for conventional chemotherapy may actually impede effective drug development. Clinical approval for most novel anti-cancer drugs has been denied due to uncertainty in optimal usage, and the modes of action unclear.[3] For a better understanding of variations, from cell to cell, in response to metal-based drugs, single cell analysis is the key. Single cell experiments should provide critical information about the pathway and disease state, which will guide personalised medicine and therapeutic strategies. Electrochemistry is the foremost approach for studying the uptake of metal-based drugs in single cells. This strategy involves positioning a micro or nanoelectrodes inside or near the surface of a single cell for the electrochemical monitoring of individual cellular events.[4]
In this work, the aim is to exploit single cell electrochemical analysis, to study the uptake of silver-based bioinorganic drugs and to elucidate the mode of action. Single cell electrochemistry experiments were carried out using the platinum and platinum-black nanoelectrodes on human lung carcinoma (A549) cell lines. Speciation studies of the silver-phenanthroline bioinorganic drugs was examined using stripping voltammetry for metal detection, and the redox behaviour analysis by cyclic voltammetry for in vitro and single cell analysis.
[1] Andrew G. Ewing. et al., Anal. Chem. 2019, 91, 1, 588-621
[2] Glenn Deng. et al., Front Cell Dev Biol. 2016, 4: 116.
[3] Walter Berger. et al., ESMO Open. 2017, 2(3): e000239.
[4] Dechen Jiang. et al., ACS Sens. 2018, 3 (2), 242–250
Estimation of Molecular Orientation Using Water Drop Angle
Authors: Hirao Kohki , Murakami Takuya , Maeda Atsushi 
Published: February 2020

In self-assembled monolayer, SAM, molecules are attracted each other to be closely packed. Such a structural feature causes the stable mechanical, chemical, and thermo-dynamical properties. In addition, recent preparation techniques allowed the direct electronic coupling between organic functionality and Si substrate. As the results, SAMs possess great potential in the fields of electrochemical sensors and molecular electronics. From the viewpoint of application, it is desirable to precisely estimate the molecular orientation in SAMs. In the present study, we propose the structural analysis using water drop angle.
To form hexadecyl-SAMs, hydrogen-terminated Si substrate was soaked in 1-hexadecene under UV light for 2 hours. UV light is capable of breaking Si-H bond homolytically, which yields the Si dangling bonds that can act as the starting point for radical chain propagation.
When a droplet is attached to SAM and the SAM surface is tilted little by little, the droplet will lunge forward and finally slide downward. The tilting angle when the droplet starts sliding is called ‘water drop angle’, WDA. We measured WDA by an original system, in which sample surface could be simultaneously tilted and rotated from 0 to 90 and from 0 to 360 degrees, respectively.
Figure 1(a) shows the typical measurement results for the hexadecyl-SAMs. WDAs were found to considerably change with the rotation angles. In addition, the period in the WDA change was nearly equal to 180 degrees. Here in-plane rotation angle was defined the orientation flat of the wafer, Si(111)<110>, as 0 degree. We believe that the periodic change is in relation to the molecular orientation. Namely, when a sample is tilted in the direction as shown in Fig. 1(b), a droplet is hooked by the SAM molecules, resulting in the large WDAs. On the other hand, in the case of Fig. 1(c), the friction between a droplet and the SAM surface is expected to be weak, corresponding to the small WDAs. The maximum WDAs for the hexadecyl-SAMs were observed at the rotation angles about 210 degrees. To justify these experimental results, it is extremely important to notice that the sterific hindrance between the (Si-C-)C-H bonds of the SAM molecules and the surrounding unreacted Si-H bonds should be minimum in six molecular orientation. As a result, the WDA reasonably exhibited the maximum value at the rotation angles of 210 degrees. In the ECS meeting, we will indicate that our measurement method is useful to estimate the orientation direction of the molecules covalently-bonded to the solid surface.

Figure 1