bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ UV-Vis Reflectance Spectroscopy Study of Bromide Oxidation on a Platinum Rotating Disk Electrode in Aqueous Solutions
Authors: Xu Jing , Georgescu Nicholas Stefan , Scherson Daniel 
Published: February 2020

In situ reflection absorption UV-visible spectroscopy was used to detect solution phase products generated during the oxidation of bromide on the surface of a polycrystalline platinum rotating disk electrode, Pt(poly) RDE, as a function of the applied potential and rotation rate, ω, in 0.01M KBr in 0.1M HClO4 aqueous solutions.
The experimental set up employed for these measurements was similar to that described by Shi et al.1 involving, in this case, a Cary 60 spectrophotometer and a modified set of reflection optics. The data collected were analyzed by theoretical simulations (COMSOL 4.3) that account for the formation of tribromide in solution using diffusion coefficients and homogeneous rates constants for the bromide|tribromide reaction reported earlier in the literature2, 3, expect for the diffusion coefficient of bromide which was adjusted to achieve a better fit, i.e. DBr
- =2.66 ×10-5 cm2/s, as opposed to DBr
- =2.08 ×10-5 cm2/s as reported in the literature4.
Statistical analyses of the Ilim vs √ω (E = 1.4 V vs RHE), data yielded both for the experimental (see black symbols) and theoretical data (red symbols) best fit straight lines with virtually identical slopes and close to zero intercepts (see caption, Fig. 1).
Shown in black symbols in Fig. 2, are potential difference UV visible reflection absorption spectra recorded simultaneously at a wavelength, λ = 266 nm, which corresponds to the absorption maxima of the peak associated with tribromide in solution.2 Also shown therein (see red symbols) are the results of the theoretical simulations. Although the slopes of the linear fits seem in very good agreement, the experimental results appear higher than the theoretical ones. The most likely origin of this effect relates to changes in the intensity of the reflected light induced both by the adsorption of bromide and the formation of a layer of oxide on the Pt surface at the high potentials at which the oxidation of bromide was monitored5.

REFERENCES

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Analytical Quality Solid-State Composite Reference Electrode
Authors: Sokalski Tomasz , Lewenstam Andrzej , Granholm Kim , Mousavi Zekra 
Published: February 2020

The reference electrode is an indispensable part of an electrochemical measurement setup and its role is to establish a precise, stable, and reproducible potential which is independent of the sample composition [1]. Internal filling solution used in conventional reference electrodes causes many drawbacks and inconveniences [2]. There are several papers proposing alternative ways of eliminating the inner filling solutions. The reference electrodes proposed there are indeed interesting from the scientific point of view but they should be further developed to be of practical applicability. The classical reference electrodes have so far been superior in terms of continuous, prolonged, and intensive usage.
A new type of all-solid-state reference electrodes based on a polymer/inorganic salt composite (SSC) was designed and characterized. Both a chemical polymerisation method [3] and an injection moulding method [4] were used for fabricating those novel electrodes.
A rigorous testing procedure was used to reveal possible influence of pH, solution composition, as well as the concentrations and mobility of ions. The tests demonstrated the insensitivity of the electrodes to the matrix effects, excellent stability of the potential readings, and significantly reduced leakage of inorganic salt. It was shown that composite reference electrodes were on par or better in the performed tests than high-quality commercial reference electrodes. The SSC reference electrodes described here are of analytical quality allowing for continuous, prolonged, and intensive usage.
References
1. G. Inzelt, A. Lewenstam, F. Scholz Handbook of reference elctrodes (2013) Springer, Berlin.
2. T. Blaz, J. Migdalski, A. Lewenstam, Analyst 130 (2005) 637-643.
3. Z. Mousavi, K. Granholm, T. Sokalski, A. Lewenstam, Analyst 138 (2013) 5216-5220.
4. K. Granholm, Z. Mousavi, T. Sokalski, Andrzej Lewenstam, J Solid State Electrochem DOI 10.1007/s10008-013-2294-x
Acknowledgements
The study was supported by the SalWe Research Program for IMO (Tekes -the Finnish Funding Agency for Technology and Innovation grant 648/10).
Simple Voltammetric Method for the Determination of the Partition and Diffusion Coefficients in Solvent Polymeric Membranes
Authors: Lindner Erno , Sheppard James , Kivlehan Francine , Pendley Bradford , Chaum Edward 
Published: February 2020

For feedback controlled monitoring of the popular anesthetic drug propofol we used an organic membrane-coated voltammetric sensor.1 The membrane coating prevents electrode fouling, and provides outstanding detection limit and selectivity for the voltametric working electrode that is adequate for continuous monitoring of propofol in whole blood in the presence of physiologically relevant interferences.
The detection limit of the voltametric sensor is controlled by diffusion coefficient (D) and the concentration of the analyte in the membrane (cM), where cM is a function of membrane/solution partition coefficient (P). The selectivity of the membrane-coated sensor, on the other hand, depends on the partition coefficients of the analyte and interfering compounds.
To assess the attainable detection limit and selectivity of the membrane coated sensor the diffusion and the partition coefficients have to be known. For the determination of the diffusion coefficients in the membrane it has been loaded with the analyte and the steady state current of a membrane coated planar electrochemical cell with a carbon fiber ultra microelectrode has been recorded in air (D=i/(4nFcMr)). By placing the membrane-coated planar electrochemical cell into a solution the concentration of the analyte in the membrane will be determined by its partition coefficients. From cyclic voltammetric experiments with the membrane-coated sensor in an analyte solutions one can calculate the partition coefficient of the analyte.
In our contribution we discuss the unique advantages of the voltammetric method and report the partition coefficients of a variety of compounds (e.g., propofol, ascorbic acid, p-acetamido phenol) between plasticized PVC membranes and aqueous electrolytes as well as the diffusion coefficients of these compounds in the membranes.
1. Kivlehan, F.; Garay, F.; Guo, J. D.; Chaum, E.; Lindner, E., Anal. Chem. 2012, 84 (18), 7670-7676.
Role of Conducting Polymers on Potentiometric and Floating Gate Field Effect Transistor (FGFET) Array-Based Immunoassays
Authors: Levon Kalle 
Published: February 2020

Semiconductor-based diagnostics have revolutionized genome sequencing since the application of ion-sensitive field effect systems for the monitoring of pH changes during the polymerization of DNA. Similar charge-dependent changes can be monitored during protein-protein binding as in antibody-antigen reaction-based immunoassays. Organic semiconductors have several beneficial effects with such CMOS FET arrays. First, the organic semiconducting layer makes the covalent conjugation of the biospecific ligands on the gate surface very convenient: We have successfully used both thiolation and glutaraldehyde linkage, especially with polyaniline layer on the floating gate. Interfacial electrochemical polymerization gives the important control of surface area with the nanofiber formation for improved sensitivity. Depending on the device architecture, the band-gap engineering for optimal Schottky barrier performance or the additional capacitive effects, both give amplified threshold voltage changes.
We have designed and manufactured autonomic floating gate (FG) field-effect transistor (FET) arrays and used them for monitoring biological reactions The advantage of FGFET array is that with a floating gate, the threshold voltage doesn't need to be “scanned”, but only the shifts in the threshold can be monitored. We compared the FET array in both IS (with reference electrode) and FGFET architecture to follow pH changes and bindings of cationic and anionic polyelectrolytes, always with a conducting polymer layer coated on the floating gate. Further on, we followed the change in the threshold voltage during protein binding on the surface, and also the effect of enzymatic substrate reacting with the conjugated enzyme as in the traditional ELISA test.
Oxygen Plasma Functionalized Graphene Nanoplatelets As Support for Pt Catalyst
Authors: Chetty Raghuram , Drzal Lawrence T. 
Published: February 2020

Fuel cell technology offers an attractive combination of highly efficient fuel utilization and environmentally friendly operation. Numerous efforts have been made in the past decade to develop materials for proton exchange membrane fuel cells. Among them, the catalyst support used for decreasing the usage of noble metals (e.g. platinum) and increase the utilization of catalyst is one of the key materials.
Since the discovery of graphene, a great deal of work has been focused on the development of graphene for energy conversion and storage applications because of its high surface area, high degree of graphitization and excellent electrical conductivity. The highly oriented basal plane structures in pristine graphene may provide many of the desired properties, however, results show poor wetting and reduced interaction with deposited metal particles when used as an electrocatalyst support. To overcome these problems, graphene is subjected to surface modification. In this work, we have used oxygen plasma treatment for the functionalization of Graphene Nanoplatelets (GnP) and then Pt nanoparticles were synthesized by a simple microwave process in the presence of ionic liquids on the functionalized GnP. The electrocatalysts were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, electron microscopy and X-ray diffraction techniques, and their electrocatalytic activity towards methanol oxidation was studied and compared to a conventional carbon support.
Enhancing MRI Relaxivity of the Gd3+ Ions Coordinated to Carboxylated Highly Water-Soluble Graphene Nanoribbons
Authors: Gizzatov Ayrat , Keshishian Vazrik , Guven Adem , Dimiev Ayrat M. , Qu Feifei , Muthupillai Raja , Bryant Robert G. , Tour James M. , Wilson Lon J. 
Published: February 2020

Magnetic resonance imaging (MRI) is a powerful tool for diagnostic medicine.1 One of applications of MRI is the ability to track cells and nanoconstucts in vivo. For this purpose chemical contrast agents (CAs) need to be internalized into cells to exhibit both safe cell internalization and enhanced proton relaxivity per Gd3+ion, so that the amount of internalized CA is as minimal as possible.
In this work, we report that Gd3+ ions coordinated to carboxylated surfactant-free highly water-soluble graphene nanoribbons2 (GNRs) result in Gd/GNRs (as shown in Figure 1a-d) to produce enhanced r1 and r2 relaxivities, which are up to 20 times higher when compared to the commercially-available MRI CA, magnevist. Here we also show that the new Gd/GNR CAs can be used for T1 and T2 weighted MRI imaging (Figure 1e,f). Also, taking into account the lipophilic nature of the Gd/GNRs, they possible can be used for cell internalization as has been previously shown for other honeycomb carbon-based nanostructures such as gadonanotubes3 and gadofullerenes.4Available results will be reported.
ACKNOWLEDGEMENTS
A. Gizzatov, V. K., A. Guven, and L. J. W. acknowledge The Welch Foundation (C-0627) for partial support of this work, while A. M. D. and J. M. T. acknowledge the ONR (#00006766, N00014-09-1-1066), the AFOSR MURI (FA9550-12-1-0035), and the AFOSR (FA9550-09-1-0581).
REFERENCES
1. P. Caravan, J. J. Ellison, T. J. McMurry, R. B. Lauffer, Chem. Rev. 99, 2293 (1999).
2. A. Gizzatov, A. Dimiev, Y. Mackeyev, J. M. Tour, L. J. Wilson, Chem. Commun. 48, 5602 (2012).
3. L. A. Tran, R. Krishnamurthy, R. Muthupillai, M. G. Cabreira-Hansen, J. T. Willerson, E. C. Perin, L. J. Wilson, Biomaterials 31, 9482 (2010).
4. B. Sitharaman, L. A. Tran, Q. P. Pham, R. D. Bolskar, R. Muthupillai, S. D. Flamm, A. G. Mikos, L. J. Wilson, Contrast Media Mol. Imaging 2, 139 (2007).
Figure 1. TEM images of a) Gd/GNRs and b) GNRs. Electron dispersion spectroscopy - TEM mapping for Gd3+c) Gd/GNRs and d) GNRs. (scale bars = 600 nm). MRI images of e) T1-weighted MRI inversion recovery phantom images acquired at different inversion times (TI) for the GNR, Gd/GNR samples in aqueous solutions and H2O at 1.5 T and f) T2-weighted MRI spin-echo phantom images acquired at different echo times (TE) for the GNR, Gd/GNR samples in aqueous solutions and H2O at 1.5 T.
Optimal Charging Profile for Mechanically Constrained Lithium-Ion Batteries Using Reformulated Pseudo Two Dimensional Models
Authors: Suthar Bharatkumar , Northrop Paul W. C. , De Sumitava , Ramadesigan Venkatasailanathan , Braatz Richard D. , Subramanian Venkat R. 
Published: February 2020

This presentation considers the problem of obtaining the optimal current profile for charging a lithium-ion battery using the reformulated porous electrode pseudo 2D (P2D) model. Our previous efforts (1) in deriving the optimal charging profile considering intercalation-induced stress were limited to single particle level dynamics of an electrode. At higher charge/discharge rates, the dynamics at the sandwich level (anode, separator and cathode) become critical and are considered a natural extension to the previous work. Optimal charging profiles will be derived by incorporating stress into the reformulated P2D model (2). Faster computing and advancement in nonlinear programming algorithms have made it possible to use nonlinear transport and electrochemical engineering-based models (3) to derive optimal charging profiles in real time.
When conventional charging profiles for lithium-ion batteries (e.g., constant current followed by constant voltage) are deployed, they do not consider capacity fade mechanisms. These charging profiles are not only inefficient in terms of lifetime usage of the batteries but also slower (4) as they do not exploit the changing dynamics of the system. The progress made in understanding the capacity fade mechanisms (5-8) has paved the way for including that knowledge in deriving optimal control. This work explores the possibilities of using transport and electrochemical-based models in deriving open-loop optimal charging profiles that minimize capacity fade by restricting the development of stresses in the solid phase as well as other capacity fade mechanisms.

Acknowledgements

The work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000275.

References

1. B. Suthar, V. Ramadesigan, S. De, R. D. Braatz and V. Subramanian, Physical Chemistry Chemical Physics (2013).
2. P. W. C. Northrop, V. Ramadesigan, S. De and V. R. Subramanian, J. Electrochem. Soc., 158, A1461 (2011).
3. S. Santhanagopalan, Q. Guo, P. Ramadass and R. E. White, Journal of Power Sources, 156, 620 (2006).
4. R. Klein, N. A. Chaturvedi, J. Christensen, J. Ahmed, R. Findeisen and A. Kojic, Proceedings of the American Control Conference, p. 382 (2011).
5. J. Christensen and J. Newman, J Solid State Electr, 10, 293 (2006).
6. S. K. Rahimian, S. C. Rayman and R. E. White, J. Electrochem. Soc., 157, A1302 (2010).
7. P. Arora, R. E. White and M. Doyle, J. Electrochem. Soc., 145, 3647 (1998).
8. R. Deshpande, M. Verbrugge, Y.-T. Cheng, J. Wang and P. Liu, J. Electrochem. Soc., 159, A1730 (2012).
Mechanism Study of Crack Formation at Si Thin Film Anodes with Different Crystalline during Lithiation/Delithation
Authors: Jung Changhoon , Jung Heechul , Ko Dong-su , Kim Heegoo , Byun Sunjung , Moon Eui-seong , Jeon Woo Sung 
Published: February 2020

Thin film electrodes have the advantage for fundamental study owing to the ability to not use binder and conductive additive in testing them as anodes. Particularly, Si thin film electrodes have attracted the most attention due to their superior cyclic performance and high initial coulombic efficiency. It is well known that the problem is crack formation which leads to poor cycle ability during charge/discharge at Si thin films.
In order to study the behavior of crack formation at Si anodes with different crystalline, amorphous Si (a-Si) thin films have been treated by laser annealing technique. When the heat exceeds the melting point of the a-Si, the Si melt and it generally form polycrystalline structures (p-Si) during re-solidification.
Crystalline of a-Si is dramatically transformed to p-Si of cylindrical column type whose diameter ranges from tens of nanometers to hundred nanometers in p-Si thin film by the laser annealing as shown in Fig. 1.
We prepared two adjacent Si patterns, whose size is 30 μm × 30 μm, with different crystalline. At initial stage, we found that the behavior of crack formation was very different in term of shape, size, and density of cracks.
In this work, the cracking feature of Si films with different crystalline after first and 30th cycles has been investigated.
Fig.1. Optical and cross-sectional TEM images of a-Si, and p-Si thin film.
Strain Effects in Heterogeneous Oxide Electrolyte Films
Authors: Shen Weida , Jiang Jun , Hertz Joshua L. 
Published: February 2020

A number of opportunities exist to use thin film deposition methods to nanoengineer materials so that we can understand and improve their ion transport behavior and other electrochemical properties. Here, we describe experiments on sputter-deposited ceramic films with controlled, heterogeneous chemical composition. Films are created using a technique developed in our lab where pure, single-element targets are reactively co-sputtered to create ceria-zirconia films where both the host and dopant atom concentrations can be controlled at the nanometer scale through the film thickness. The ionic conductivity of all samples was determined using impedance spectroscopy in the temperature range 573 K to 1073 K and over a range of oxygen partial pressures.
Two sets of results using this system will be presented. First, we will discuss films made to have heterogeneous dopant content. By placing the dopants in 2-D atomic planes, defects are trapped in engineered space charge zones surrounding the interface, and vacancy-dopant associations can be studied. Specifically, by comparing samples using heterogeneous La, Gd, or Y dopants, the role of strain in the mobility and concentration of defects in the space charge region is examined, with larger dopant ion correlated to increased space charge conductivity. A second system to be presented will involve modulation of the Ce/Zr ratio through the thickness. Since the lattice parameter is a linear function of Ce/Zr ratio, these samples can be used to smoothly and systematically control lattice strain. Strain was determined by x-ray diffraction and microscopy, including selected area electron diffraction. Clear differences in interfacial structure are found as the lattice parameter differential between the layers is adjusted. The strained multilayers indicate both a strain-based change in vacancy mobility and a general reduction in conductivity as the interfacial density increases.
Spatial Fluctuation Fluorescence Spectroscopy: A New Method for Studying Single-Walled Carbon Nanotube Dispersions
Authors: Streit Jason K. , Bachilo Sergei M. , Weisman R. Bruce 
Published: February 2020

We describe a novel spectroscopic method that has been applied to characterize liquid suspensions of single-walled carbon nanotubes (SWCNTs). When fluorescence spectra are sequentially measured from small volumes of very dilute samples, the intensities of emission features can fluctuate significantly because relatively few nanotubes of each type are present within the observation volume, and these concentrations vary statistically from observation to observation. By restricting acquisition times to ~200 ms and slowly flowing the sample so that a different region is sampled by each spectrum, we can observe such spatial concentration variations as spectral intensity fluctuations. Using observation volumes of only 10-7 mL and sample mass concentrations down to ~60 ng/mL, we acquire sequences of 3000 spectral snapshots and then analyze the set of data. At each emission wavelength, we compute the mean intensity and the variance (squared standard deviation) of intensity. The ratio of squared mean intensity to variance is then plotted as a function of wavelength to give an abundance spectrum, reflecting the number of nanoparticles contributing to emission at that wavelength.
Spatial fluctuation spectroscopy thus gives relatively direct access to the absolute (n,m) composition of SWCNT samples. Another benefit of this technique is that emission features from different (n,m) SWCNTs are better resolved in the variance spectrum than in the squared mean emission spectrum, allowing clearer detection of species with overlapping fluorescence spectra. In addition, the mean intensity spectrum can be divided by the abundance spectrum to obtain the relative fluorescence efficiency per nanotube for all of the (n,m) species represented in the data. These values can be used to validate the calibration factors that are central to conventional quantitative fluorimetric analysis of mixed SWCNT samples.
Furthermore, we have analyzed the spectral data sets to find correlations between signal fluctuations at different wavelengths. These are interpreted as reflecting the spatial correlations of nanotubes of different types, which implies the presence of aggregates. Studies will be reported showing how these cross-correlations depend on sample condition and processing. Spatial fluctuation spectroscopy appears to be a powerful new tool for analyzing and studying SWCNT suspensions.
Invited Presentation: Photoluminescence Imaging Probes of Contrasting 1-D and 0-D Exciton Behavior in Doped Carbon Nanotubes
Authors: Doorn Stephen K. , Yamaguchi Hisato , Yalcin Sibel , Ma Xuedan , Htoon Han 
Published: February 2020

Introduction of new photoluminescent (PL) states upon low-level covalent doping of carbon nanotubes1,2 is gaining interest due to their chemical stability and potential for tube brightening. The nature of these optical states is not yet well-understood. We present PL imaging and spectroscopic studies of oxygen-doped tubes1 at the single-tube and single-dopant site levels. Dynamic and static emission behaviors will be presented as modulated by the relative dopant concentration. Results will be discussed as the interplay of 1-D bright exciton behaviors and 0-D trap states introduced at the dopant sites.
1. S. Ghosh, et al., Science, 330, 1656 (2010).
2. Y. Piao, et al., Nature Chem., 5, 840 (2013).