bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local Generation of Reactive Oxygen Species at New Polymer-Modified Electrodes
Authors: Wittstock Gunther , Dongmo Saustin , Witt Julia , Dosche Carsten 
Published: February 2020

Recently the ability of quinone compound to generate reactive oxygen species has been investigated [1]. The importance of quinone compounds in living organism was widely reported and its therapeutic effect through generation of free radicals has been studied [1-4]. In fact, the efficacy of a monolayer of quinone compound and their polymer film on electrodes to catalyze the reduction of oxygen has been evaluated [1, 2]. It has been mentioned that plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) possess also cytotoxic properties and has been exploited to produce polymer films which can be used as a controllable source of reactive oxygen species [1]. The two core functionalities of plumbagin allow to produce a redox film and at the same time to preserve the ability of the redox moiety to generate the reactive oxygen species [1]. Nevertheless, in all case the question on the nature of the formed reactive oxygen species generated is still open. In our procedure we obtained stable films of adjustable thickness by first chemically grafting a monolayer of plumbagin to an activated glassy carbon electrode followed by electropolymerization of further layers of plumbagin. These films grew to defined thickness while electropolymerization of plumbagin directly on a glassy carbon electrode led to self-inhibiting insulating films.
The obtained films showed catalytic activity of oxygen reduction. The interest was placed on the generations of hydrogen peroxide and specially superoxide radical with the final aim of design a microscopic generator for future scanning electrochemical microscopic study. The generation of hydrogen peroxide and possible generation of superoxide radical were monitored with lateral resolution by fluorescence microscopy coupled with the high speed camera and by chronoamperometric detection using biosensor based on cytochrome c.
References
[1] L. A. A. Newton, E. Cowham, D. G. Sharp, R. Leslie and J. Davis, New J. Chem.
34, 2010, 395–397.
[2] M.M. Ardakani, P.E. Karami, H.R. Zare and M. Hamzehloo, Microchim. Acta.
159, 2010, 165-173.
[3] H.Shimada, Y.Yamaoka, R. Morita, T.Mizuno, K.Gotoh, T. Higuchi, T. Shiraishi and Y.Imamura, Toxicology in Vitro
26, 2012, 252-257.
[4] V.Sivakumar, R.Prakash, M.R. Murali, H.Devaraj and S.N.Devaraj, Drug and Chemical Toxicology
28, 2005, 499-507
Composites of Polypyrrole with Micelles Nanospheres
Authors: Gryczan Piotr , Maksymiuk Krzysztof , Kisiel Anna , Michalska Agata 
Published: February 2020

Alternating polymers were used to obtain self assembling micelles – nanospheres. In the polymer structure every second unit is maleic anhydride (poly(maleic anhydride alt-1-octadecene)), as upon spontaneous hydrolysis anhydride groups are transformed into carboxyl groups resulting in stability of thus obtained particles (micelles) in aqueous environment [1]. Crosslinking can be achieved in course of reaction with bis(hexamethylene)triamine.
Thus obtained nanospheres have size close to ~150 nm and negative surface charge, due to the presence of carboxyl groups on the surface. The above mentioned structures were incorporated into polypyrrole films, obtained electrochemically, where micelles with ionized carboxyl groups served as negative counter ions. The polymer was characterized by stable voltammetric responses and very well separated potential ranges corresponding to anion– and cation–exchanging properties (in contrast to classical polypyrrole / polystyrenesulfonate films, where overlapping of these ranges was observed). Potentiometric sensitivity of these films can be switched between anionic and cationic characteristics by appropriate conditioning / polarization. Polypyrrole / nanospheres composites exhibit also significant pH sensitivity both in voltammetric and potentiometric mode, resulting from the presence of carboxyl groups.
Controllable sensitivity to various groups of ions and possibility of ions accumulation is promising for analytical applications of these composites, because of the fact that nanospheres can be loaded with compounds of choice, e.g. ionophores or catalytic centers [2].

T. Pellegrino, L. Manna, S. Kudera, T. Liedl, D. Koktysh, A. L. Rogach, S. Keller, J. Rädler,
G. Natile, W. J. Parak, Hydrophobic nanocrystals coated with an amphiphilic polymer shell: a general route to water soluble nanocrystals. Nano Lett.
2004, 4. 703-707.

A. Kisiel, K. Kłucińska, Z. Głębicka, M. Gniadek, K. Maksymiuk, A. Michalska, Alternating polymer micelle nanospheres for optical sensing. Analyst, 2014, 139. 2515-2524.
Manipulation of Nanoscale Pattern Formation in Photoelectrochemically Deposited Chalcogenide Films Using Multiple Beam Illumination
Authors: Carim Azhar , Batara Nicholas , Premkumar Anjali , Atwater Harry A , Lewis Nathan S. 
Published: February 2020

Photoelectrochemical deposition of semiconducting chalcogenide films resulted in the spontaneous generation of ordered nanostructures wherein the pattern developed is a function of the illumination utilized during growth. Film adopted an ordered, highly anisotropic lamella-type pattern when deposited under conformal illumination with polarized light. Feature size and pitch were controlled the illumination wavelength, direction of anisotropy by the polarization vector and the growth direction by the incident light vector. In order to progress toward generation of intricate, 3-dimensional architectures for specific applications, the manipulation of the pattern formation by utilizing simultaneous illumination from multiple discrete beams during deposition has been investigated. Illumination with two parallel polarized, narrowband sources with two discrete mean wavelengths resulted in patterns with periods that were intermediate of those that would be expected for either source alone and a function of the relative source intensities. The use of two linearly polarized sources with polarization vectors separated by an acute angle produced structures oriented in a direction between the two polarization vectors: this direction was a function of the relative intensities and mean wavelengths of the sources. Illumination with orthogonally polarized sources provided for the generation of mesh-type structures wherein the periodicity and height of pattern in the two orthogonal, in-plane directions could be controlled independently by varying the intensities and wavelengths of the sources. Modeling of the growth was achieved with a Monte Carlo process wherein the probability of mass-addition was weighted based on simulations of the light-matter interactions in the films.
This photoelectrochemical deposition process is unique from other methods of generating ordered mesostructures with electrochemical means as no photomask, no photoactive substrate, no physically patterned substrate, nor any chemical templating agents (ligands, surfactants) were utilized. Additionally, tuning the deposition potential and electrolyte along with the illumination has enabled control of the material composition. The same general morphology was observed for a range of varying materials. Thus, this process displays significant, increasing potential to possibly enable the generation of complex morphologies for functional materials without some of the limitations imposed by traditional fabrication techniques.
Benchmarking of Heterogeneous CO2 Reduction Reaction Electrocatalysts
Authors: Ferrer Ivonne M. , McCrory Charles C L , Peters Jonas C , Jaramillo Thomas F 
Published: February 2020

The identification of earth abundant, efficient electrocatalysts for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR) is crucial for the development of solar-fuels devices. Historically, procedures and conditions used for the evaluation of various electrocatalysts differ from laboratory to laboratory, resulting in performance metrics that are not easily compared. We have developed a benchmarking protocol that allows for the consistent assessment of activity, stability, electrochemically-active surface area and Faradaic efficiencies of electrocatalysts. Using this benchmarking protocol, we have evaluated the performance of over 50 HER and OER electrocatalyts. The standardized evaluation of OER and HER electrocatalysts has allowed us to identify important trends for the advancement of solar-fuels research. More recently, we have developed electrochemical methods for the standardized analysis of electrocatalysts for CO2RR. This has included the development of analytical methods for standardized identification and quantification of CO2 reduction products. Given the complexity of CO2 reduction reactions and the variety of products that can be formed depending upon the catalyst, product analysis plays a key role on the Benchmarking of CO2 reduction catalysts. Herein, we present benchamrking of CO2RR catalysts and the analytical methods developed for the identification and quantification of liquid and gaseous products.
Calculating the Proton Transport and Dielectric Properties of Phosphates and Related Materials
Authors: Tuckerman Mark E. 
Published: February 2020

Phosphate based systems are cosidered to be promising electrolyte materials for use in fuel cells. It is know, for example, that liquid phosphoric acid has the highest known intrinsic proton conductivity of any substance. However, little is known about the microscopic mechanisms of proton conduction is phosphate based systems or about their dielectric properties. In this talk, I will discuss efforts we have made to elucidate these properties in pure phosphoric acid, phosphoric acid with imidazole (as a model for the types of stabilizers often used in phosphoric acid fuel cells) and in related phosphonic anc phosphinic acid systems for comparison. The approaches used mostly rely on first-principles molecular dynamics calculations, which are able to treat the bond-breaking and forming events associated with proton transport, however, I will also discuss the performance of several force fields applied to these systems, which also allow us to test finite-size effects (system sizes are, by necessity, small in first-principles molecular dynamics calculations) and effecdts of simulation length (simulation lengths are also, by necessity, short in first-principles molecular dynamics).. As will be discusssed in the talk, by examining diffusion, kinetics, microscopic mechanisms, and dipole distributions, we have garnered considerable new insights into these ccomplex systems.
Mathematical Modeling of Multi-Physics Electrochemical Devices
Authors: Farrell Troy W. 
Published: February 2020

Electrochemical devices such as batteries and electrochemical solar cells are often described as multi-physics devices. This is a catch-all term meant to convey the fact that these devices are inherently multi-scale, multi-component and multi-phase in nature and that their operation involves complicated interfacial charge transfer and bulk solid and solution phase charge transport. Consequently, the development of accurate and meaningful mathematical models and numerical simulations for such devices is a complex task. Such modelling however, can play a vital role in the optimization of these devices via the identification of the key parameters that control their operational behaviour for a range of conditions and material configurations.
In this presentation we will consider examples from some of the authors previous(1-10) and current work on the mathematical modelling of multi-physics electrochemical devices such as battery electrodes, solar cells and nano-diodes to highlight the challenges, approaches and outcomes of such modelling.
REFERENCES

T. W. Farrell, C. P. Please, D. L. S. McElwain and D. A. J. Swinkels, J. Electrochem. Soc., 147, 4034 (2000).

T. W. Farrell and C. P. Please, J. Electrochem. Soc., 152, A1930 (2005).

M.A. Penny, T.W. Farrell and G.D. Will, Sol. Energy Mat. & Sol. Cells, 92, 24-37, 2008.

Troy Farrell and Steven Psaltis, in Physics of Nanostructured Solar Cells, eds. V. Badescu and M. Paulescu, pp. 327-353, Nova Science Publishers, Inc., New York, ISBN: 978-1-60876-110-4, 2010.

S. Dargaville and T.W. Farrell, J. Electrochem. Soc., 157, A830 (2010).

S. T. P. Psaltis and T. W. Farrell, J. Electrochem Soc., 158, A33 (2010).

S. Dargaville and T.W. Farrell, Electrochimica Acta,
94

(1), pp. 143-158 (2013).

S. Dargaville and T.W. Farrell, Electrochimica Acta,
111
, pp. 474-490 (2013).

S. Dargaville and T.W. Farrell, Journal of Computational and Applied Mathematics, 273, pp 255-244 (2014).

S. Psaltis, T. Farrell, K. Burrage, P. McCabe, T. Moroney, I. Turner and S. Mazumder, “Mathematical Modelling of Gas Production and Compositional Shift of a CSG Field: Local Mo del Development”, submitted to Energy (2014).
Simulations of Phase Transformation Dynamics in LiFePO4 Particles in Battery Electrode
Authors: Yu Hui-Chia , Orvananos Bernardo , Akyildiz Oncu , Thornton Katsuyo 
Published: February 2020

Lithium iron phosphate (LFP) has been a successful material for Li-ion battery cathodes due to its enhanced safety and rate capability. For cathodes consisting of LFP nanoparticles, the current-voltage response in macroscopic electrochemical measurements exhibits a feature indicative of solid-solid phase transformation during the charge-discharge processes. However, the Li concentration evolution within individual nanoparticles remains to be elucidated.
In this work, we used phase field modeling to investigate the effects of a variety of material parameters and their anisotropies on the morphological evolution of the lithiated and delithiated phases in cathode particles. An elliptical particle of 45 and 35 nm in diameters along the longest and shortest axes was used in the simulations. This particle was assumed to be immersed in electrolyte and to be placed in contact with a current collector. To simulate the lithium concentration evolution during the electrochemical process, six coupled governing equations were solved self-consistently. These equations describe lithium transport in (1) the particle and (2) the electrolyte, electrostatic potential in (3) the particle and (4) the electrolyte, (5) the electrochemical reaction rate at the particle surface, and (6) mechanical equilibrium in the particle.
The highly anisotropic material properties of LFP reported in the literature were adopted as the simulation parameters, including lithium diffusivities, interfacial energies, surface insertion rate, electronic conductivity, misfit strain, and elastic moduli. To examine the individual and combined effects from these parameters, the simulation parameters were altered from the reported values in our parametric studies. By exploring the material parameter space, we found that the anisotropy of electronic conductivity is the dominant factor in determining phase evolution in a bare LFP particle (without conductive coating). In contrast, for a carbon-coated particle, the anisotropy in electronic conductivity loses its significance and the lithiation process becomes more isotropic.
This work was supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583.

Figure 1
Molecular Simulations of Proton and Hydroxide Transport in Fuel Cell Membranes
Authors: Tse Ying-Lung Steve , Savage John , Chen Chen , Knight Chris , Voth Gregory 
Published: February 2020

Acid/base reactions are ubiquitous in nature and they have received extensive experimental and theoretical attention over the past several decades. Even though we now understand reasonably well how the Grotthuss hopping mechanism is responsible for the rapid charge diffusion in aqueous acidic and basic solutions, the mechanisms for long-range proton and hydroxide transport in fuel cell membranes are not nearly as well understood. While there is similarity in the solvation structures for the hydroxide and the hydronium ions, the underlying hopping mechanisms in both cases have significant differences. Through careful parameterization based on ab initio calculations, accurate and efficient multistate reactive molecular dynamics (MS-RMD) models are constructed to study proton and hydroxide transport in both proton-exchange and anion-exchange membrane (PEM and AEM) systems. These MS-RMD models allow for the calculations of statistically converged properties and reveal important transport mechanisms in these energy materials. In this talk, the mechanistic pictures of proton and hydroxide transport in PEM and AEM will be discussed and compared.
Figure Caption: The left figure shows the typical solvation structures around hydronium ions (green) in the 3M PEM and illustrates how a hydronium bridges two sulfonates. The right figure shows the solvation around hydroxide ions (green) in poly(vinyl benzyl trimethylammonium) AEM.
Acknowledgment: This research used resources of Research Computing Center (RCC) at the University of Chicago, the Innovative and Novel Computational Impact on Theory and Experiment (INCITE), ASCR Leadership Computing Challenge (ALCC) programs, and the Argonne Leadership Computing Facility (ALCF) at Argonne National Laboratory (Supported by DOE contract DE-AC02-06CH11357).

Figure 1
First-Principles Based Modeling of Structures and Processes at Electrochemical Electrode-Electrolyte Interfaces
Authors: Gross Axel 
Published: February 2020

In spite of its technological relevance in the energy conversion and storage,
our knowledge about the microscopic structure of electrochemical
electrode-electrolyte interfaces and electrical double layers is still rather
limited. The theoretical description of these interfaces from first
principles is hampered by three facts. i) In electrochemistry, structures and
properties of the electrode-electrolyte interfaces are governed by the
electrode potential which adds considerable complexity to the theoretical
treatment since charged surfaces have to be considered. ii) The theoretical
treatment of processes at solid-liquid interfaces includes a proper
description of the liquid which requires to determine free energies instead of
just total energies. This means that computationally expensive statistical
averages have to be performed. iii) Electronic structure methods based on
density functional theory (DFT) combine numerical efficiency with a
satisfactory accuracy. However, there are severe shortcomings of the DFT
description of liquids, in particular water, using current functionals.
Despite these obstacles, there has already significant progress been made in
the first-principles modeling of electrochemical electrode-electrolyte
interfaces. In this contribution, I will present our attempts to contribute to
this progress by systematically increasing the complexity of the considered
systems [1, 2]. Different approaches to describe aqueous electrolytes at
electrodes using first-principles calculations will be compared: the
electrolyte can be described either as a thermodynamic reservoir or using
implicit of explicit solvent models. The equilibrium coverage of specifically
adsorbed anions such as halides will be addressed which is an integral part
of the realistic modeling of electrochemical double layers. Finally,
first attempts to model the structure of battery electrodes using electronic
structure calculations will be presented.
[1] Axel Gross, Florian Gossenberger, Xiaohang Lin, Maryam Naderian, Sung
Sakong, and Tanglaw Roman, Water structures at metal electrodes studied by
ab initio molecular dynamics simulations, J. Electrochem. Soc. 161, E3015-E3020 (2014).
[2] Nicolas Hoermann, Markus Jaeckle, Florian Gossenberger, Tanglaw Roman,
Katrin Forster-Tonigold, Maryam Naderian, Sung Sakong, and Axel Gross,
Some challenges in the first-principles modeling of structures and processes
in electrochemical energy storage and transfer, J. Power Sources 275, 531-538 (2015).
Defect Chemistry of CeO2 Surfaces from First Principles and Space Charge Theory
Authors: Bjoerheim Tor Svendsen , Kotomin Eugene , Maier Joachim 
Published: February 2020

CeO2 (ceria) is a diverse oxide with numerous technologically important functional properties. It is one of the most studied oxygen incorporation materials, and exhibits remarkable catalytic properties towards hydrocarbon and CO oxidation, and water splitting reactions.1-3 Further, acceptor doped ceria is of great interest as electrolyte for solid oxide fuel cells due to its considerable oxide ion conductivity at intermediate temperatures.4 Recently, nanocrystalline CeO2 ceramics were shown to display significant proton conduction even at room temperature,5 suggested to be due to surface, or sub-surface proton migration. The majority of these functional properties are affected by, or even originate from the rich surface, or interface defect chemistry of ceria, and corresponding space charge layers.3
,
6

In this contribution, we explore the defect chemistry of various surface terminations of CeO2 at finite temperatures, by combining first principles calculations and space charge theory. Plane-wave based electronic/atomic structure calculations at the GGA+U and hybrid HF-DFT levels are used to determine bulk defect formation energetics and the defects' surface segregation energies in CeO2. The first principles results are further combined with space charge theory through numerical evaluation of the space charge potential profiles and corresponding defect concentration profiles.
The charged oxygen vacancies and protonic defects exhibit highly favorable surface segregation energies, and therefore tend to accumulate on CeO2 surfaces. Although such accumulation is partly charge compensated by oxide and hydroxide ad-ions and Ce3+ species at the surface, the surface turns out to be overall positively charged, and charge-compensated by a negative sub-surface space charge region, at least for low defect concentrations. Under humid conditions, especially at lower temperatures, the surfaces are saturated by protonic species, forming water layers. Finally, the effect of such surface saturation by protonic species, and also H2O monolayer and film formation on the sub-surface space charge potential and defect concentration profiles are discussed.
1. A. Trovarelli, Catalysis Reviews, 1996, 38, 439-520.
2. E. P. Murray, T. Tsai and S. A. Barnett, Nature, 1999, 400, 649-651.
3. Z. A. Feng, F. El Gabaly, X. Ye, Z.-X. Shen and W. C. Chueh, Nat Commun, 2014, 5.
4. H. L. Tuller and A. S. Nowick, Journal of The Electrochemical Society, 1975, 122, 255-259.
5. E. Ruiz-Trejo and J. Kilner, Journal of Applied Electrochemistry, 2009, 39, 523-528.
6. G. Gregori, M. Shirpour and J. Maier, Advanced Functional Materials, 2013, 23, 5861-5867.