bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Discovering Wide Band Gap Oxide Semiconductors By Engineering Strong Electron Correlations
Authors: Ramanathan Shriram 
Published: February 2020

Wide gap semiconductors are often designed based on energy separation of the cation and oxygen orbitals. In strongly correlated semiconductors, however interacting electrons create effective transport gaps based on the occupancy of orbitals. I will discuss some recent examples from our laboratory on discovery of new electronic phases that have gaps of the order of 3eV that have been designed by electron doping of perovskite nickelates. In the un-doped case, these systems possess small gaps of the order of 0.1eV, and adding electrons to the partially filled d-orbitals, enhances the gap to 3eV taking advantage of strong correlations in the eg orbitals of Ni sites. This new strategy allows us to create wide gaps in semiconductors that are nominally metallic or nearly-metallic like in the pristine state and could be expanded to a broader range of materials systems. Besides the gap opening that in itself is fascinating, there are several opportunities to tune these materials to achieve multiple resistance states, continuous tuning of resistance by anion-site disorder and create multi-functionality. I will then give some examples of their applications in neural science and engineering, photonics and evolutionary biology.
High Performance Radiation-Grafted Anion Conducting Polymer Electrolytes for Energy Applications
Authors: Ponce Gonzalez Julia , Wang Lianqin , Santiago Elisabete , Bance-Soualhi Rachida , Whelligan Daniel , Biancolli Ana-Laura , Varcoe John 
Published: February 2020

This presentation will describe the latest research at the University of Surrey and the development of radiation-grafted anion-exchange membranes (RG-AEM) and ionomer powders (AEI) for use in devices such as alkali membrane fuel cells.
The presentation will provide an overview of the following recent achievements:

Synthesis of RG-AEMs with heterocyclic chemistries that are more stable to alkali that the those containing the benzyltrimethylammonium benchmark;

Synthesis protocols that require reduced radiation doses, reduced amounts of monomer and the use of water rather than organic solvents;

Synthesis of thinner RG-AEMs;

The ability to produce RG-AEMs based on low density polyethylene (LDPE) rather than partially fluorinated ETFE;

Synthesis of an interesting class of solid-state AEI powders;

AEMs with high hydroxide conductivities and high performances in H2/O2 fuel cells.

For example, the graph show the beginning-of-life 60°C H2/O2 fuel cell performances achieved with Pt-based catalysts and RG-AEMs made from 25 μm ETFE (red) and 13 μm ETFE (green) with no gas back-pressurization applied.

References:

Ponce-Gonzalez et al., Energy Environ. Sci., 2016, 9, 3724-3735
Wang et al., Green Chem., 2016, Advanced Article DOI: 10.1039/C6GC02526A.

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Unraveling Fundamental Descriptors for the Structural and Morphological Degradation of Pt Nanoparticles on Indium Tin Oxide Using in Situ Techniques
Authors: Schmies Henrike , Bergmann Arno , Wang Guanxiong , Drnec Jakub , Kühl Stefanie , Sandbeck Daniel , Mayrhofer Karl , Ramani Vijay K , Cherevko Serhiy , Strasser Peter 
Published: February 2020

Enhancing stability of cathode catalysts for PEMFC applications under operating conditions is of great importance because state-of-art supports for nanoparticular Pt electrocatalysts suffer from carbon corrosion especially during start-stop procedure. Metal oxides have been proven to be viable alternatives because of their corrosion resistance and observed strong metal support interaction which is thought to enhance activity as well as stability of the catalyst [1-3]. Tin-based oxides excel by their thermal stability as well as high conductivity and are therefore promising candidates as alternative fuel cell support materials [4]. But the structural evolution of Pt-based nanoparticles under electrochemical conditions on oxides is still unknown. On high surface area carbon it has been shown by using in-situ SAXS studies that Pt nanoparticles grow due to Ostwald ripening and a dissolution/redeposition mechanism decreasing the electrochemical active surface area (ECSA) [5].
Here, we report on metal oxide supported Pt nanoparticles focussing on the structural evolution under electrochemical potential cycling applied to mimic fuel cell operating conditions. The Pt nanoparticles were synthesized using a solvothermal route and deposited on Indium Tin Oxide (ITO) resulting in homogenously distributed particles with well defined size. The electrocatalysts were extensively tested with respect to long-term electrochemical stability in order to investigate its potential as alternative carbon-free support material. We determined the evolution of crystal structure, composition, crystallite size and particle size distribution of the oxide support and the Pt nanoparticles by using in situ XRD and ASAXS. Additionally, we were able to follow the dissolution of the catalyst components during the electrochemical protocol using SFC ICP-MS setup. We can show that in case of ITO the size of Pt nanoparticles increases only slightly, whereas the mass-based catalytic activity decreases primarily due to changes of the support. Furthermore, our results show that we are able to unravel fundamental aspects of morphological degradation of Pt nanoparticles on non-carbon supports under electrochemical conditions. These results will help to understand stability determining properties of oxide supports leading to enhanced cathode electrocatalysts for a PEMFC.
[1] A. Kumar, V. Ramani, J. Electrochem. Soc.
2013, 160, F1207-F15.
[2] A. Lewera, L. Timperman, A. Roguska, N. Alonso-Vante, J. Phys. Chem. C
2011, 115, 20153-59.
[3] T.T.H. Van, C.J. Pan, J. Rick, W.N. Su, B.J. Hwang, J. Am. Chem. Soc.
2011, 133, 11716-24.
[4] H.-S. Oh, H.N. Nong, P. Strasser, Adv. Funct. Mater.
2015, 25, 1074-81.
[5] X. Tuaev, S. Rudi, V. Petkov, A. Hoell, P. Strasser, Acs Nano
2013, 7, 5666-74.
(Invited) Electrochemical Characterization of Complete La0.6Sr0.4Co1-XFeXO3-δ Composition Phase Space By Microelectrode Impedance Spectroscopy
Authors: Kucharczyk Christopher J , Liang Yangang , Choi Sihyuk , Zhang Xiaohang , Takeuchi Ichiro , Haile Sossina M 
Published: February 2020

Solid oxide fuel cells are a promising clean energy technology due to their high efficiency and fuel flexibility, but current commercialization efforts are limited by expensive components needed to withstand high operating temperatures [1]. Attempts to decrease operating temperature have been stymied in large part by cathode materials with high polarization resistance [2], and efforts to improve performance through composite electrode morphologies [3] lead to complex geometries that prevent rigorous comparisons between different materials. We present a case study employing a novel methodology [4] for electrode characterization that enables fundamental property determination of multiple electrode compositions and allows for rigorous performance comparisons.
In this work, the entire composition phase space of a state-of-the-art ion- and electron-conducting solid oxide fuel cell cathode material (La0.6Sr0.4Co1-xFexO3-δ) is examined with unprecedented compositional resolution (x=0 to x=1 with Δx=0.05). Gradient pulsed laser deposition was employed to obtain a compositionally graded thin film on a (100)-oriented 8 mol% Y2O3-ZrO2 electrolyte substrate. The film was patterned using photolithography and ion milling to obtain electronically isolated circular microdot electrodes ranging from 80-500 µm in diameter. Microelectrode impedance spectroscopy was performed with a robotic scanning probe in an environmental chamber to obtain relevant electrochemical parameters. The measured impedance spectra are consistent with a two-phase boundary electrochemical pathway including bulk ionic conduction through the oxide. A monotonic increase in electrochemical resistance is observed from La0.6Sr0.4CoO3–δ (LSC) to La0.6Sr0.4FeO3–δ (LSF) along with a decrease in chemical capacitance corresponding to a decrease in reducibility and oxygen vacancy concentration. This case study demonstrates the rich insights that can be gleaned from this high-throughput approach and its promising application toward searching for new high-performance solid oxide fuel cell electrode materials.
1. Yang, Z.G., Recent advances in metallic interconnects for solid oxide fuel cells. International Materials Reviews, 2008. 53(1): p. 39-54.
2. Kuklja, M.M., et al., Combined theoretical and experimental analysis of processes determining cathode performance in solid oxide fuel cells. Physical Chemistry Chemical Physics, 2013. 15(15): p. 5443-5471.
3. Sun, C.W., R. Hui, and J. Roller, Cathode materials for solid oxide fuel cells: a review. Journal of Solid State Electrochemistry, 2010. 14(7): p. 1125-1144.
4. Usiskin, R.E., et al., Probing the reaction pathway in (La0.8Sr0.2)(0.95)MnO3+delta using libraries of thin film microelectrodes. Journal of Materials Chemistry A, 2015. 3(38): p. 19330-19345.
(Invited) From Fundamentals to PEMFC Systems
Authors: Lv Haifeng , Li Dongguo , Lopes Pietro Papa , Strmcnik Dusan , Wang Rongyue , Markovic Nenad M , Stamenkovic Vojislav 
Published: February 2020

Search for active and durable, but cost effective catalysts that can be employed in fuel cells remains one of the main challenges for broad application of this technology. This presentation intends to provide an overview of progress that has been made in design of Pt-based electrocatalysts that are currently used in low temperature fuel cells. The main focus will be placed on necessity to resolve current limitations at molecular scale, which can ultimately lead towards design of electrocatalysts with advanced properties.
A major challenge lies in the insufficient activity and durability of materials that are currently employed as cathode catalysts for electrochemical reduction of oxygen. These limitations inevitably lead to a lower operating efficiency of the devices, which highlights the need for development of more active and durable oxygen reduction reaction catalysts. Consequently, the majority of research efforts are placed on the catalyst design and synthesis aiming to improve their efficiency. It has been found that properties such as surface structure, surface and subsurface composition associated with electronic properties have distinguished roles in determining functional properties of electrocatalysts. In addition to the catalyst materials it is of paramount importance to emphasize the role of liquid phase which is influencing on the overall properties of an electrified interface. Molecular species from employed electrolyte and the nature of their interaction with catalyst surfaces can be used in tuning the PEMFC performance.
(Invited) Tortuosity and Effective Transport Properties for Porous Materials in Electrochemical System
Authors: Fuller Thomas F , Star Andrew G. 
Published: February 2020

Modeling has become an instrumental tool is the design and development of electrochemical systems. Multiple length and time scales are treated, but perhaps the most import and well developed models are macrohomogeneous physical models. These are typified by the porous electrode models advanced by Newman and others. These porous electrode models have been applied with great success to a variety of batteries, fuel cells, and double layer capacitors. The detailed geometry isn’t used, but instead effective transport properties account for the reduction in the magnitudes of diffusivities and conductivities. These effective transport properties are measured experimentally or often estimated using the Bruggeman relationship.
It has been well documented that the Bruggeman relationship is far from universal. These limitations are not unexpected considering the basis for the relationship between porosity and tortuosity. It should be clear that a simple relationship is not adequate. Consider, for instance shape changes in the electrode of battery undergoing cycling. The porosity may be unchanged, but effective transport properties vary. The Bruggeman relationship cannot explain this behavior.
Although the community generally agrees upon the concept of tortuosity, the ratio of effective path length to thickness of material through which transport occurs, multiple mathematical definitions exist. These descriptions are explored here. From the detailed geometry, the reverse problem can be solved, namely calculate and effective transport property and then calculate tortuosity from .
More recently, computation tools and methods to image electrode have improved dramatically. There are still many challenges, but more and more detailed geometries of electrodes are becoming available. Focused-ion-beam techniques combined with scanning electron microscopy (FIB/SEM) is such an example. Resolution on the order of tens of nanometers is routine. These developments allow us to begin to answer questions such as how to bridge length-scales between molecular dynamic and macroscopic models? Can we calculate a property of the porous media akin to a tortuosity that is both well-defined and relevant to the effective transport properties that we seek for the macroscopic models? These questions are explored through an example of the corrosion of the cathode of a PEM fuel cell.
(Invited) Materials By Design for Energy Applications: Incorporating Metastability
Authors: Tumas William 
Published: February 2020

Meeting our future global energy needs in an environmentally responsible way is perhaps the greatest challenge facing the world in the twenty first century. The discovery of new functional materials is critical to developing the needed disruptive technologies for energy conversion, delivery, storage, and use. Remarkable advances in theory and high-throughput materials synthesis and characterization are enabling a new approach to new materials discovery where theory can directly guide experimental materials discovery and development.
This talk will present recent results from a number of research groups within the Next Generation for Materials by Design (CNGMD) Energy Frontier Research Center (EFRC), a multi-institution funded by DOE. Our overall goal is to design, discover and synthesize new energy-relevant functional materials, including non-equilibrium structures, with targeted functionalities by integrating theory, high-throughput computation, synthesis, and characterization. Our focus is on semiconductor materials for renewable energy and energy efficiency applications including solar energy conversion, solid-state lighting, solar fuel production and piezoelectrics. A primary goal is to incorporate functional metastable materials into materials by design and establish ranges for materials metastability as a function of the chemistry, energetics, and structure. We are examining three classes of metastable systems: defects, polymorphs, and solid solutions (alloys). We are also trying to develop a systematic theory-driven approach to guide the synthesis of new materials—including metastable systems—by coupling theory and state-of-the-art in-situ characterization to probe materials growth pathways. Highlights from our research will be presented including: Pnictide Search where we are exploring new metal nitrides to discover new functional semiconductor materials; Polymorphs and Synthesizability where we are understanding energy landscapes and identifying synthetic pathways for specific polymorphs focusing on Mn and Ti oxides; Chalcogenide Alloys where we predict and guide the synthesis of new functional semiconductor alloy materials; and Perovskite-Inspired Materials Search which designs new materials based on the electronic features of defect tolerance and long carrier lifetimes observed in hybrid organic-inorganic halide perovskites.
(Invited) Crosscutting Research in the Critical Materials Institute
Authors: Schwegler Eric 
Published: February 2020

The Critical Materials Institute (CMI) is an Energy Innovation Hub that is led by the U.S. Department of Energy's Ames Laboratory. CMI is focused on the research and development of technologies that can diversify the sources of critical materials; provide substitutes for materials that are in short supply; or improve the utilization of existing resources through enhanced efficiency in manufacturing and improved recycling. Within CMI, the Crosscutting Research Focus Area has been working to accelerate the development of these new technologies by ensuring that CMI research teams have ready access to key tools and capabilities, such as advanced electronic structure approaches for identifying new magnets and phosphors with reduced rare earth element content, and unique experimental techniques for high-throughput synthesis and characterization of alloy materials. Much of our work in this area is being carried out with the Materials Genome Initiative (MGI) framework where computational, experimental, and data informatics tools are tightly coupled in a materials innovation infrastructure. In this talk, I will review several recent examples where CMI has used the MGI approach to achieve significant speedups in the development of technologies that address materials criticality issues. Prepared by LLNL under Contract DE-AC52-07NA27344.
One-Pot Anodic Thiocyanation and Isothiocyanation of Alkenes
Authors: Becker James Y. , Levy Avishai 
Published: February 2020

Previously we studied the anodic thiocyanation of aromatic compounds [1, 2]. The one-pot anodic thiocyanation and isothiocyanation of alkenes in both acidic two-phase (water-dichloromethane) and homogeneous one-phase (water-acetonitrile) media will be described [3]. A selected example of type of products obtained is illustrated in the scheme below:
References
[1] A. Gitkis, J.Y. Becker, J. Electroanal. Chem., 593 (2006) 29-33.
[2] A. Gitkis, J.Y. Becker, Electrochim. Acta, 55 (2010) 5854-5859.
[3] A. Levy, J.Y. Becker, Electrochim. Acta, 178 (2015) 294–302.

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Organic Electrochemistry Goes to Work: Genotoxicity Sensor Arrays
Authors: Rusling James F , Kadimisetty Karteek , Malla Spundana , Bist Itti 
Published: February 2020

This paper focuses on fundamental concepts derived from the technical evolution of organic electrochemistry that have helped us to develop sensors for the chemistry of genotoxicity, which is essentially the damage of DNA by chemicals and their metabolites. This research is driven by the need to screen for the possibility of genotoxicity of new environmental chemicals and drug candidates, about 30% of which have toxicity issues that do not manifest until clinical trials on humans. A major issue is metabolic chemistry driven mainly by cytochrome (cyt) P450s and other metabolic enzymes. Metabolic chemistry involves catalysis of organic reactions, oxidations in the case of cyt P450s. We found ways to inject electrons into cyt P450s in thin films via their native reductase electron-transfer partners to catalyze metabolic reactions electrochemically via mechanisms that are the same as in our livers. This is organic electrochemistry.
For the sensors, we needed a way to detect the resulting metabolite-related DNA damage in sensors combining thin LbL films of metabolic enzymes and DNA in which the metabolites are generated and react with DNA. We found that guanines in DNA chains can react in an electrocatalytic process involving a Ru metallopolymer (RuPVP) and provide a strong visible light output via electrochemiluminescence (ECL). This electrocatalytic process oxidizes RuII in the polymer to RuIII to oxidize guanine moieties in the DNA, and a complex redox reaction sequence produces the light. The catalytic oxidation current can also be measured. Organic electro-oxidations are responsible for these outputs. Similar approaches can be used to design sensor arrays that monitor DNA oxidation.
Electrocatalytic Cyt P450 oxidations and ECL generation are combined in our most sophisticated genotoxicity sensor arrays. When DNA is damaged, its double-stranded structure is disrupted and RuIII sites in the film gain better access to guanine moieties to produce more ECL light, or more catalytic current. Examples, including the genotoxic potential of e-cigarettes, will be discussed.
(Keynote) Electrochemical Reduction of Bromobenzenes at Silver Cathodes
Authors: Pence Michael Andrew , Peters Dennis G , Mubarak Mohammad S. 
Published: February 2020

In 1959, it was observed that poly-halogenated arenes would undergo a halogen dance under very basic conditions.1 Later, in a study of the electrochemical reduction of halogenated thiophenes at glassy carbon cathodes, an electrochemically induced halogen dance was discovered.2 Halobenzenes were studied shortly after and it was found that 1,2,4,5-tetrabromobenzene would undergo an electrochemically induced halogen dance at glassy carbon in dimethylformamide with 0.10 M tetramethylammonium perchlorate as the supporting electrolyte.3 In the present study, we have investigated a possible halogen dance resulting from the reduction of poly-brominated benzenes at a silver cathode for comparison with known behavior at glassy carbon cathodes. Cyclic voltammograms (CVs) of di-, tri-, and tetrabromobenzenes were recorded at a scan rate of 100 mV/s with a silver cathode in dimethylformamide containing 0.1 M tetramethylammonium perchlorate as a supporting electrolyte. All potentials are reported versus a Cd/Hg amalgam reference electrode with a potential of –0.76 vs SCE. CVs of 2 mM 1,2,4,5-tetrabromobenzene exhibit three peaks, the most positive of which is found at –0.70 V; a small shoulder is also present at –0.65 V. Controlled-potential (bulk) electrolysis of 1,2,4,5-tetrabromobenzene at –0.65 V vs. Cd/Hg yielded 1,2,4- and 1,3,5-tribromobenzene in trace amounts. Products were confirmed by means of GC–MS. The presence of 1,3,5-tribromobenzene among electrolysis products indicates the occurance of a halogen dance following the reduction of the first bromine–carbon bond. Due to similar reduction potentials for multiple carbon–bromine bonds at silver, complete removal of only a single halogen is difficult; to better isolate a single electron-transfer event, other halogenated benzenes were investigated. CVs of 2 mM 1-bromo-2,4,5-trichlorobenzene also exhibited three peaks, with the most positive at –0.50 V, separated by 800 mV from the next reduction peak. This large peak separation allows for more complete electrolysis and quantitation of halogen-dance products, aiding in development of a mechanism for the reduction of halogenated benzenes at a silver cathode.

References

Wotiz, J.; Huba, F. J. Org. Chem., 1959, 24, 595–598.

Mubarak, M. S.; Peters, D. G. J. Org. Chem., 1996, 61, 8074–8078.

Mubarak, M. S.; Peters, D. G. J. Electroanal. Chem., 1997, 435, 47-53.

Figure 1