bluuebunny/crossref_metadata_2025 huggingface dataset:
Immobilization of Glucose Oxidase on 4-(pyrrole-1-yl) Benzoic Acid Functionalized Carbon Nanotubes for Direct Electrochemistry and Glucose Sensing
Authors: Kowalewska Barbara , Jakubow Katarzyna
Published: February 2020

In recent years, carbon nanotubes (CNT) have gained considerable attention, because of their remarkable electronic and mechanical properties, which have made them extremely attractive for a wide range of sensing applications from structural materials to nanoelectronic components. The ability of CNT-modified electrodes to promote electron transfer reactions has been documented in connection with important biomolecules [1]. Our goal is to explore new applications of CNT as an electrode material in facilitating the electron transfer between enzyme molecule and electrode in the bioelectrocatalytic system for glucose oxidation that is of potential utility for bioelectronic devices such as biosensors and biofuel cells.

Our research focuses on the direct electrochemical performance of glucose oxidase (GOx) immobilized on 4-(pyrrole-1-yl) benzoic acid (PyBA) modified multi-walled carbon nanotubes (CNTs). GOx is a homodimer containing two tightly bound flavin adenine dinucleotide (FAD) redox centers embedded deeply in the enzyme [2]. Modification of carbon nanostructures allow to obtain thin and organized films, causing a rapid and effective transfer of electrons between the active center of the biocatalyst (GOx) and the electrode surface. The presence of PyBA in our composite film significantly improves their stability and introduces new functional groups that have great importance in the enzyme immobilization process onto the CNTs-modified electrode [3].

In this work stable immobilization and direct electron transfer of glucose oxidase were achieved on the composite film modified glassy carbon electrode. The resulting electrode gave a well-defined redox peaks with a formal potential of about −440 mV (vs. Ag/AgCl) in 0.1 phosphate buffer solution pH=7.0. The electron transfer rate constant was estimated to be 3.15 s-1, due to the combined contribution of CNTs/PyBA and GOx. Furthermore, the method for detecting of glucose was proposed based on the decrease of oxygen caused by the enzyme-catalyzed reaction between GOx and glucose. The low calculated apparent Michaelis–Menten constant (KM
app) was 10.2 mM, implying the high enzymatic activity and affinity of immobilized enzyme for glucose. It can reasonably be expected that this observation might hold true for other noble carbon nanostructure-electroactive protein systems, providing a promising platform for the development of biosensors and biofuel cells.

References

[1] J.J.Gooding, R.Wibowo, J. Liu, W. Yang, D. Losic, S. Orbons, F.J. Mearns, J.G. Shapter, D.B. Ilibbert, J. Am. Chem. Soc. 125 (2003) 9006.

[2] H.J. Hecht, H.M. Kalisz, J. Hendle, R.D. Shmid, D.Schomburg, J. Mol. Biol. 229 (1993) 153.

[3] B. Kowalewska, M. Skunik, K. Karnicka, K. Miecznikowski, M. Chojak, G. Ginalska, A. Belcarz, P.J. Kulesza, Electrochim. Acta 53 (2008) 2408.
Understanding the Mechanisms of Proton Transport in Hydrogen Bonded Media from First-Principle Molecular Dynamics
Authors: Tuckerman Mark
Published: February 2020

Proton transport in aqueous and non-aqueous hydrogen-bonded media has long been an area of intense study due to its fundamental importance in emerging energy technologies such as hydrogen fuel cells and in biological problems such as proton pumping. Our understanding of proton transport phenomena is based on the concept structural diffusion of a topological defect in the hydrogen bond network originally proposed by C. J. T. von Grotthuss in 1806. Within this picture, long-range proton transport is driven by specific structural rearrangements in the local hydrogen bonding environment, however, pinning down the specific microscopic mechanisms in different media remains an immense challenge that has an immediate impact on the problem of designing novel materials for enhancing the proton transport process. In this talk, I will show how first-principles molecular dynamics has contributed to our understanding of proton transport phenomena in a variety of systems including aqueous acidic and basic solutions, acid hydrate crystals, and phosphate based materials including pure phosphoric acid and its mixtures with heterocycles. It will be shown that proton transport in aqueous systems relies largely on local fluctuations in the hydrogen bond network while phosphate systems, by contrast, transport protons along extended, polarized chains in a manner much closer to the original picture suggested by von Grotthuss.
Oxygen Transport in Perovskite-Type Materials for SOFCs Cathodes: What Can We Learn from Quantum Mechanics
Authors: Muñoz-García Ana Belén , Pavone Michele , Ritzmann Andrew Marc , Carter Emily A.
Published: February 2020

Effective, rational design of innovative, low-cost materials with high oxygen reduction reaction (ORR) catalytic activity at intermediate temperatures (ITs) requires a deep understanding of the underlying reaction mechanisms of oxygen incorporation and diffusion in solid oxide fuel cell (SOFC) cathodes.

We use state-of-the-art first-principles calculations in order to gain atomic scale insights into the relationships between composition, structure, and transport properties of traditional perovskite-type cathode materials ABO3 (A=La, Sr; B=Mn, Fe, Co, Cr) and the new, promising Sr2Fe1.5Mo0.5O6-δ
electrode. Specifically, we study the factors that govern bulk oxide ion diffusion in these materials, namely, the oxygen vacancy formation energy and migration barrier, as well as the surface features that allow the dissociation and incorporation of oxygen.

Beyond quantitative agreement with measurements, our results provide new insights into the origin of the observed material behavior. The electronic structure of the B-site transition metal, the A-site cation charge and the B-O bond nature are the main features that determine perovskite cathode performance. The subtle interplay of long-range electrostatics and local electronic effects is ultimately responsible for vacancy formation, ion and transport, and electronic conductivity. All these properties and processes can be fine-tuned by appropriate choices of A- and B-site constituent elements and aliovalent substitutions at each site. The ratio and nature of the additives are crucial for obtaining the desired performance.

Our findings provide foundational and systematic understanding of perovskite bulk and surface properties and of the emergent ORR performance so that new generations of effective SOFC cathodes can be developed.

[1] Muñoz-García, A. B.; Pavone, M.; Carter, E. A. Chem. Mater. 2011, 23, 4525–4536.

[2] Pavone, M.; Ritzmann, A. M.; Carter, E. A. Energy Environ. Sci. 2011, 4, 4933–4937.

[3] Muñoz-García, A. B.; Bugaris, D. E.; Pavone, M.; Hodges, J. P.; Huq, A.; Chen, F.; zur Loye, H.-C.; Carter, E. A. J. Am. Chem. Soc. 2012, 134, 6826–6833

[4] Muñoz-García, A. B.; Pavone, M.; Ritzmann, A. M.; Carter, E. A. Phys. Chem. Chem. Phys 2013, 15, 6250–6259.

[5] Ritzmann, A. M.; Muñoz-García, A. B.; Pavone, M.; Keith, J. A.; Carter, E. A. Chem. Mater. 2013, 25, 3011–3019.

[6] Ritzmann, A. M.; Muñoz-García, A. B.; Pavone, M.; Keith, J. A.; Carter, E. A. MRS Commun. 2013, 3, 161–166.
Chronoamperometric In Situ Measurement of the Specific Conductivity of a Thin Film on the Disc Electrode Surface
Authors: Vorotyntsev Mikhail A , Konev Dmitry V
Published: February 2020

A new method to measure both the total resistance and the specific conductivity of a thin film (for the current flow in the normal direction) is proposed [1].

It is assumed that the film has been deposited on the surface of a disc electrode (in static or rotating conditions). A relatively small diameter of the disc is preferable to ensure the maximal uniformity of the film along the surface. The thickness of the film, Lf, should be sufficiently small compared to the disc radius, ro, but it should cover the surface in a uniform manner. The conductivity properties of the deposited material may be isotropic or anisotropic (different in the normal and tangential directions).

The primary and secondary distributions of the electric potential and the current after a small-amplitude potential step have been analyzed for such a film-coated electrode in contact with an electrolyte solution, CE and RE being located sufficiently far from the disc electrode (WE). The three-dimensional (3D) character of these distributions inside the solution has been taken into account.

Analytical expressions have been derived for the overall short-time resistance of the system, Rtot, with taking into account the contributions of both the solution and the film. Due to the 3D effect this quantity for the primary distribution is not equal to the sum of the short-time resistances of these components of the system, Rs for solution and Rf for the film. Analytical formulas have been deduced, allowing one to calculate immediately the film resistance, Rf, on the basis of measured values of Rtot and Rs. Then, the specific conductivity of the film, kf, is found from relation: kf = Lf / Rf pro
2.

Both parameters of the film may be determined by this method for a set of electrode potential values, see Fig.1 for a poly(titanocene-propyl-pyrrole) film.

The merits of this procedure to determine the high-frequency transport parameters are: 1) film deposition at a small surface area (but still macroscopic) substrate; 2) no lower restriction for the film thickness (except for their uniformity); 3) in situ measurements inside the conventional cell; 4) non-destructive procedure (film may be used for further texts); 5) simple data treatment; 6) weak effects of local film's imperfections, etc.

Support of RFFI (projects 09-03-01172 and 10-08-00847) is acknowledged.

Fig. 1 Dependence of the specific conductivity of the poly(titanocene-propyl-pyrrole) film on the potential.

[1]. M.A. Vorotyntsev, D.V. Konev / Electrochim. Acta 56 (2011) 9105– 9112
The Physical Properties of Room Temperature Ionic Liquids Near Electrified Surfaces: A Simulation Study
Authors: HU Zongzhi , Vatamanu Jenel , Bedrov Dmitry
Published: February 2020

The influence of the electrode geometry and electrolyte chemical structure on the electrode-electrolyte interfacial properties and electrode capacity are discussed based on an extensive theoretical study of several room temperature ionic liquids near flat, corrugated and curved electrodes. The flat and curved electrode surface generates a weakly changing capacitance versus potential for a large variety of electrolytes investigated. However, a dramatically different behavior of capacity, and enhanced capacities were observed for rough electrodes. An atomistic explanation of the observed electrode-electrolyte structure and its implication on capacity dependence on voltage will be proposed. We will review and discuss possible origins of several major discrepancies experiment-theory regarding the prediction of electrode differential capacitance shape versus potential and the controversial issue of temperature dependence of the capacitance.
Dielectric Properties of Hydrated Perfluorosulfonic acid membranes
Authors: Minutolo Anthony , Wang Chen , Paddison Stephen , Sangoro Joshua
Published: February 2020

Broadband Dielectric Spectroscopy is employed to investigate the link between hydrated morphology, local water dynamics and charge transport in a series of commercially available Perfluorosulfonic Acid (PFSA)

membranes of different equivalent weights and hydration levels[1-2]. Different experimental set-ups are used to determine dielectric properties of both dry and hydrated membranes in a wide frequency range spanning more than 11 orders of magnitude. The dielectric spectra are dominated by long-range proton conduction on the low frequency regime and local water dynamics at higher frequencies. The results are discussed within the framework of recent studies of charge transport in nano-confined membranes.

References

1. K.-D. Kreuer, M. Schuster, B. Obliers, O. Diat, U. Traub, A. Fuchs, U. Klock, S. J. Paddison and J. Maier, J. Power Sources, 178, 499 (2008).

2. G. A. Giffin, G. M. Haugen, S. J. Hamrock, and V.D. Noto, Journal of the American Chemical Society,

135
(2), 822-834 (2013).
Effect of the Electrolyte Formulation on the Performances of Edlc and Li-Ion Batteries
Authors: Ghamouss Fouad , Zhang Wanjie , Dahbi Mouad , Jacquemin Johan , Tran-Van François , Monconduit Laure , Martinez Hervé , Dedryvère Rémi , Lemordant Daniel
Published: February 2020

One of the most important components in electrochemical storage devices (batteries and supercapacitors) is undoubtedly the electrolyte. The basic function of any electrolyte in these systems is the transport of ions between the positive and negative electrodes. In addition, electrochemical reactions occurring at each electrode/electrolyte interface are the origin of the current generated by storage devices. In other words, performances (capacity, power, efficiency and energy) of electrochemical storage devices are strongly related to the electrolyte properties, as well as, to the affinity for the electrolyte to selected electrode materials. Indeed, the formulation of electrolyte presenting good properties, such as high ionic conductivity and low viscosity, is then required to enhance the charge transfer reaction at electrode/electrolyte interface (e.g. charge accumulation in the case of Electrochemical Double Layer Capacitor, EDLC). For practical and safety considerations, the formulation of novel electrolytes presenting a low vapor pressure, a large liquid range temperature, a good thermal and chemical stabilities is also required.

This lecture will be focused on the effect of the electrolyte formulation on the performances of electrochemical storage devices (Li-ion batteries and supercapacitors). During which, a summary of the physical, thermal and electrochemical data obtained by our group, recently, on the formulation of novel electrolyte-based on the mixture of an ionic liquid (such as EmimNTf2 and Pyr14NTf2) and carbonate or dinitrile solvents will be presented and commented. The impact of the electrolyte formulation on the storage performances of EDLC and Li-ion batteries will be also discussed to further understand the relationship between electrolyte formulation and electrochemical performances. This talk will also be an opportunity to further discuss around the effects of additives (SEI builder: fluoroethylene carbonate and vinylene carbonate), ionic liquids, structure and nature of lithium salt (LiTFSI vs LiPF6) on the cyclability of negative electrode to then enhance the electrolyte formulation. For that, our recent results on TiSnSb and graphite negative electrodes will be presented and discussed, for example 1,2.

1-C. Marino, A. Darwiche1, N. Dupré, H.A. Wilhelm, B. Lestriez, H. Martinez, R. Dedryvère, W. Zhang, F. Ghamouss, D. Lemordant, L. Monconduit “ Study of the Electrode/Electrolyte Interface on Cycling of a Conversion Type Electrode Material in Li Batteries” J. Phys.chem. C, 2013, 117, 19302-19313

2- Mouad Dahbi, Fouad Ghamouss, Mérièm Anouti, Daniel Lemordant, François Tran-Van “Electrochemical lithiation and compatibility of graphite anode using glutaronitrile/dimethyl carbonate mixtures containing LiTFSI as electrolyte” 2013, 43, 4, 375-385.
Templating Effect of Polymeric Electrolytes on the Electropolymerization of Aniline
Authors: Nekrasov Alexander A. , Gribkova Oxana L. , Isakova Alexandra A. , Zolotarevsky Victor I. , Ivanov Victor F. , Vannikov Anatoly V.
Published: February 2020

Preparation of polyaniline (PANI) in the presence of polymeric electrolytes is known to produce the polymer with improved characteristics such as mechanical properties, thermal stability, adherence, controlled morphology, wide pH-range of electroactivity, etc. This contribution describes the results of systematic studies on the influence of the structure of water-soluble polymeric sulfonic acids on PANI electrodeposition and properties. The course of polymerization in potentiostatic, galvanostatic and potential sweep regimes was traced by chronoamperometry, chronopotentiometry, cyclic voltammetry and in situ AFM measurements. It was shown that the structure of polyacid, namely, the rigidity of the polymer backbone, the distance between sulfonic groups on the backbone, the length and rigidity of the side chains containing sulfonic groups, strongly affect the onset potential of aniline oxidation, the character and the rate of the initial stages of PANI/polyacid film growth. The in situ AFM studies performed during potentiostatic polymerization showed that the structure of polyacid (primarily the backbone rigidity) has a direct influence on the shape of PANI “nuclei” and the morphology of the film in the early stages of the electropolymerization (Fig. 1). The obtained films were also characterized by UV-Vis-NIR spectroscopy and spectroelectrochemistry and cyclic voltammetry.

This work was supported by the Russian Foundation for Basic Research (grant No.12-03-01087).
Simultaneous Electrochemical EPR in Probing the Oxygen Reduction Mechanism of Non-Precious Electrocatalysts for PEMFC
Authors: Zhang Congling , Lawton Jamie S. , Foister Shane , Goenaga Gabriel A. , Zawodzinski Thomas A.
Published: February 2020

The ORR mechanism as catalyzed by non precious metal catalysts to replace Pt based catalysts at the cathode of PEMFC has been controversial for decades, though this category of catalysts has recently achieved remarkable ORR performance.1,2 More understanding of the ORR mechanism is essential to the further improvement of the performance of catalysts of this class. Cu(II) based non precious metal catalysts are advantageous for the study of the ORR mechanism due to their biomimetic significance in mimicking copper oxidases and, when not pyrolyzed to their well defined structure.3

To gain deeper understanding of the ORR mechanism, an in situ electrochemical half cell for EPR has been designed and applied to probe the mechanism of the ORR catalyzed by a Cu(II)-3,5-diamino-1,2,4-triazole based (shown here) and other catalysts. Simultaneous observation of electrochemical behavior and the corresponding Cu(II) EPR signal evolution at different potentials was realized as shown in Figure 1. The intensity of the Cu(II) signal decreases as the potential steps negative because more Cu(II) is reduced to Cu(I) at more negative potentials. In Figure 2, the EPR spectroscopic behaviors of Cu(II) during a cyclic voltammogram are different in the presence and absence of O2, with a shift in potential indicating a complex formation between O2and Cu ions during ORR catalysis. A study of the effects of oxygen concentration will be conducted to estimate the amount of active catalytic sites in the catalyst. A quantitative relationship will be investigated to determine the reaction order of Cu species in the ORR catalysis. Finally, this method will be applied to a number of related non-precious metal catalysts.

Acknowledgements:

The authors gratefully acknowledge the support of theUS DOE Office of Fuel Cell Technology and the office of Naval Research for financial support of this work.

References:

[1]. Proietti, E.; Jaouen, F.; Lefèvre, M.; Larouche, N.; Tian, J.; Herranz, J.; Dodelet, J.-P. Nat. Commun. 2011, 2, 416

[2]. Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P. Science 2011, 332, 443–7

[3]. Thorum, M. S.; Yadav, J.; Gewirth, A. A. Angew. Chem. Int. Ed. Engl. 2009, 48, 165–7
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

Shi, P.; Scherson, D. A., Anal. Chem. 2004,
76, 2398.

Liu, Q.; Margerum. D.W. Environ. Sci. Technol. 2001, 35, 1127.

I. Ruff. J. Phys.Chem. 1972, 76, 2957.

J. Newman. Electrochemical Systems; third edition John Wiley & Sons. Inc., Hoboken, NJ, 2004.

Zhao, M.; Scherson, D. A; Anal. Chem. 1992, 64, 3064.
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.
Surface Treatment of the Activated Carbon on Capacitive Deionization
Authors: Kim Jiyoung , Peck Dong-Hyun , Lee Byungrok , Jung Doo-Hwan
Published: February 2020

The capacitive deionization (CDI) which has huge interest as an energy efficient and eco-friendly desalination process, is an electrochemically water purification technology using electro-static adsorption/desorption of ions on the charged electrode. Activated carbons are commonly used for an electrode material due to its high surface area. The surface condition of activated carbon is a remarkable point on the CDI process that repeats reversible adsorption and desorption of ions on the interface between the carbon electrode and the saline electrolyte. In this experiment, we investigated the effect of surface treatment of activated carbons on CDI performance by two kinds of commercial activated carbons which were Maxsorb-III and P-60 with a surface area of 3000, 1800m2g-1, respectively. Each activated carbon was treated by two different methods. One was to remove the surface functional groups by heat treatment in hydrogen atmosphere. Another way was to introduce the oxygen functional groups on the surface by H2O2 treatment. The characteristics such as the specific surface area and chemical states of carbon surface were evaluated by N2 adsorption isotherm and FT-IR analysis. The specific capacitance was examined using cyclic voltammetry in saline or acid electrolyte. Unit-cell CDI performances were tested and compared in a view point of surface functional groups of activated carbons
Spectroscopic Investigation of Electrochemically Charged Individual Single-Walled Carbon Nanotubes
Authors: Krauss Todd , Schafer Sebastian
Published: February 2020

Individual single walled carbon nanotubes (SWNTs) of (6,5) chirality were investigated by means of optical spectroscopy while their charge state was controlled electro-chemically. The photoluminescence of the SWNTs was found to be quenched at positive and negative potentials, where the onset and offset varied for each individual SWNT. We propose that differences in the local environment of the individual SWNT lead to a shift of the Fermi energy, resulting in a distribution of the oxidation and reduction potentials. The exciton emission energy was found to correlate with the oxidation and reduction potential. Further proof of a correlation was found by deliberately doping individual SWNTs and monitoring their photoluminescence spectral shift.
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.
Graduate Student Award of the Energy Technology Division - Solid State Award Reactivity of Hydroxyl Radicals Towards Reduced Graphene Oxide
Authors: Kamat Prashant V , Radich James
Published: February 2020

Graphene oxide (GO) based nanostructure assemblies have important applications in the development of new electrode and photocatalyst architectures. The paper discusses the reactivity of reduced graphene oxide (RGO) towards chemically and photocatalytically generated hydroxyl radicals. Presence of Au nanoparticles catalyzes the oxidative reaction and creates a new graphene morphology with nanopores and wrinkles. In the chemical generation of hydroxyl radicals, UV-photolysis of H2O2 has been employed to produce OH· radicals. Elucidation of OH· radical reactivity toward graphene is important from the perspective of material applications. It shows potential challenges with evolution of hydroxyl radicals in energy-related reactions such as TiO2 photocatalysis and fuel cell cathode O2 reduction. Understanding of the mechanism behind the oxidation of RGO to ORGO provides opportunities to suppress these unwanted reactions in photocatalytic or electrochemical systems containing graphene-based composite materials.
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

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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).

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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.
Carbon Nanotubes As Photoluminescent Quantitative Bioanalytical Sensors
Authors: Heller Daniel A
Published: February 2020

Real-time, spatially resolved detection and identification of analytes in biological media present important goals for next-generation sensors. To this end, the intrinsic near-infrared fluorescence of single-walled carbon nanotubes can be modulated by their immediate environment. The encapsulation of nanotubes in synthetic polymers and biopolymers creates a handle for the transduction of analyte binding. Small molecules, such as reactive oxygen species and other genotoxins, can be detected by transduction of the binding event to the polymer or the nanotube itself. In these cases, small molecule analyte identification is achieved by observing variations in the nanotube’s spectral response, resulting in distinct optical fingerprints. Nanotube emission can undergo both wavelength and intensity modulation, permitting the identification of analytes which are difficult to differentiate via conventional methods. The responses can be spatially mapped in live cells and tissues, and measured in real-time with sensitivity down to the single-molecule level, facilitating unprecedented bioanalytical studies.
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

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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).
The Role of Elasto-Plasticity on Phase Kinetics in Lithiated Silicon Nanowires: Phase Field Simulation
Authors: Chen Lei , Chen Long Qing , Chen James
Published: February 2020

Silicon (Si) is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. In addition to volumetric expansion, huge stresses, and fracture, recent experiments reveal that the kinetics of Li insertion and extraction, which critically control the rates of charging and discharging, are of great importance for the high performance of LIBs. Here, we first propose a phase field model coupled to elasto-plasticity to study the lithiation kinetics in individual Si nanowires. In contrast to other models, the proposed phase field model is thermodynamically consistent, and the corresponding thermodynamic and kinetics parameters can be obtained from the experiments or Density function theory (DFT) calculations. The developed model describes well the experimental known self-limiting lithiation phenomenon, which is attributed to the retardation effect of the lithiation-induced stress. Further, the proposed model has general character and is applicable to any electrode systems.
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.
The Effect of Battery Potential and Charge Rate on the Decomposition Reaction on the Anode Electrode of Lithium Ion Polymer Battery
Authors: Agubra Victor , Fergus J. W. , Fu Rujian , Choe Song-yul
Published: February 2020

The formation of the solid electrolyte interface (SEI) layer on the surface of the anode electrode prevents further electrolyte decomposition reaction. However, certain battery operating parameters initiate electrolyte solvent and salts decomposition reaction with lithium on the surface to the anode electrode. This decomposition reaction results in the formation of an insoluble reaction products that is non-uniform, electronically insulating, and unstable on the surface of the graphite particles. The loss/consumption of recyclable lithium ions at the anode by this passivation layer is one of the causes of major reversible capacity loss in the lithium ion battery. Understanding the potential and the charge rate that initiates the formation of the surface film layer is critical to effectively controlling/limiting these operational parameters in order to extend the calendar life performance of the battery. This paper seeks to investigate the effect of the state of charge and charge rate on the electrolyte decomposition reaction resulting in the formation of the surface film deposit. An image based quantitative analysis of the thickness of the surface film will be conducted to collaborate the observed changes in the electrochemical properties of the battery.
Diffusion Mechanisms in the Solid Electrolyte Interphase in Li-Ion Batteries from First Principle Calculation
Authors: Liu Zhe , Zhang Hao Wei , Qi Yue , Harris Stephen J , Lu Peng , Chen Long-Qing
Published: February 2020

The understanding of the mechanisms of Li-ion transport and electron leakage through the solid electrolyte interphase (SEI) layer is crucial to enhance the performance of rechargeable Li-ion batteries. Our study was based on a slab model of Li metal covered by Li2CO3 with contact with ethylene carbonate (EC) electrolyte. Pure Li metal is an ideal negative electrode for its high capacity and low voltage level. The layer of crystalline Li2CO3 was used to mimic the SEI layer, since our recent recognition by TEM that Li2CO3 was the component responsible for stabilizing the SEI. The barriers for Li and electron transport under applied voltage will be computed within the framework of DFT and constrained-DFT to understand the mechanism in electrochemical systems. Ab inito molecular dynamics (AIMD) simulations will be performed to explicitly track Li+ diffusion pathways. Energy profiles as a function of the electric field during this reduction reaction will be determined to understand the effects of electric field on the diffusion barrier.
Electrochemical Strain Microscopy of Doped Ceria at Elevated Temperatures
Authors: Chen Qian Nataly , Liu Yuanming , Adler Stuart , Li Jiangyu
Published: February 2020

Solid oxide fuel cells have emerged as a promising electrochemical conversion technology due to its high efficiency, stability, and low cost. A major component of these fuel cells is its electrolyte, a solid ion-conducting ceramic, which must be ionically conductive but electrically insulating. Nanocrystalline doped ceria has been explored as an electrolyte that can operate at lower temperatures, but the nature of the increased ionic conductivity is still under investigation. In this paper, electrochemical strain microscopy, a nanoscale probing technique in which an AC bias is applied to the surface of the electrolyte material, is used to evaluate induced strains on samarium doped ceria, and the corresponding electrochemistry on the surface is evaluated. Due to the typically high operating temperatures of solid oxide fuel cells, electrochemical strain microscopy was performed at varying temperatures, up to 250°C. We find that the induced strain increases proportionally with increased temperature, particularly at grain boundaries due to the space-charge effect. Furthermore, large DC biases were applied to the electrolyte at individual points, and the resulting strain relaxation after removal of the bias was measured at varying temperatures. We find here that the temperature and other environmental conditions can lead to dramatic differences in the relaxation behavior. Furthermore, the relaxation behavior along grain boundaries is also significantly different compared to the behavior on the bulk portion of the grain. Determination of the mechanisms behind such changes can lead to increased fundamental understanding of the chemical expansion behavior of ceramic electrolytes.