Search results for "Volt"
showing 10 items of 2187 documents
Characterizing archaeological bronze corrosion products intersecting electrochemical impedance measurements with voltammetry of immobilized particles
2017
Application of electrochemical impedance measurements to microparticulate deposits of copper corrosion products attached to graphite electrodes in contact with 0.10 M aqueous HClO4 electrolyte is described. The impedance measurements were sensitive to the applied potential and the amount of solid sample and were modeled taking into account the contribution of the uncovered base electrode. Several pairs of circuit elements provide monotonic variations which are able to characterize different corrosion compounds regardless the amount of microparticulate solid on the electrode. Application to a set of archaeological samples from the archaeological Roman site of Gadara (Jordan, 4th century AD) …
Fabrication of a biocompatible and continuous glucose biosensor with the poly(3,4-ethylenedioxythiophene) modified electrode
2019
Abstract In this study, we have explored the potentiality of using GOx/AuNP/PEDOT(BSA)/Pt electrode as an implantable, long-lasting, and sensitive glucose biosensor. We have examined the performance of the electrode for glucose calibration with three electrochemical measurements, such as cyclic voltammetry, linear sweep voltammetry, as well as chronoamperometry, which all exhibited strong linear correlation between resulting signal and glucose concentration. In comparison, linear sweep voltammetry gave the best linear sensitivity, whose average was about 3.124 µA/mM/cm2 within a wide glucose concentration range from 0.416 to 50 mM. Meanwhile, the stability of the electrode was confirmed by …
Characterization and Electrochemical Properties of Oxygenated Amorphous Carbon (a-C) Films
2016
Amorphous carbon (a-C) films with varying oxygen content were deposited by closed-field unbalanced magnetron sputtering with the aim to understand the effect of oxygen on the structural and physical properties of the films and subsequently correlate these changes with electrochemical properties. The a-C films were characterized by transmission electron microscopy, helium-ion microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and time-of-flight elastic recoil detection analysis. The electrochemical properties were studied by electrochemical impedance spectroscopy and cyclic voltammetry with several redox systems (Ru(NH3)62+/3+, Fe(CN)64−/3−, dopamine an…
Voltage-controlled current loops with nanofluidic diodes electrically coupled to solid state capacitors
2016
[EN] We describe experimentally and theoretically voltage-controlled current loops obtained with nanofluidic diodes immersed in aqueous salt solutions. The coupling of these soft matter diodes with conventional electronic elements such as capacitors permits simple equivalent circuits which show electrical properties reminiscent of a resistor with memory. Different conductance levels can be reproducibly achieved under a wide range of experimental conditions (input voltage amplitudes and frequencies, load capacitances, electrolyte concentrations, and single pore and multipore membranes) by electrically coupling two types of passive components: the nanopores (ionics) and the capacitors (electr…
Electrosynthesis and properties of poly(3,4-ethylenedioxythiophene) films functionalized with titanocene dichloride complex
2006
Synthesis of a titanocene dichloride derivative functionalized with 3,4-etylenedioxythiophene group, Tc1EDOT (Cl 2TiCpC5H4(CH2) (3,4ethylenedioxythiophene)) has been described. Redox behavior of the monomer in tetrahydrofuran (THF), dichloromethane (DCM) and acetonitrile (AN) at different scan rates has been discussed in terms of different ability of these solvents to coordination with the reduced titanocene (Tc) complex and the solvation of Cl − anions. Electrooxidation of Tc1EDOT to get a conducting polymer film with immobilized titanocene dichloride centers and electrochemical properties of its polymer matrix in background acetonitrile solution have been compared with those of non-substi…
Evaluation of aging processes of petroleum asphalt cements by solid state electrochemical monitoring
2018
Abstract The changes in the chemistry of organosulfur compounds from asphalt cements during aging are studied using solid state voltammetry of immobilized microparticles. Five Brazilian asphalt cements were evaluated after three forced aging processes: Rolling Thin Film Oven Test (RTFOT), Pressure Aging Vessel (PAV) and SUNTEST. It was possible to identify the presence of thiophenes, sulfides and sulfoxides in the different samples and the reactional changes during the aging processes were proposed. Voltammetric data, supported by ATR-FTIR spectroscopy, indicate that aging asphalts involve the increase of the proportion of sulfoxide and thiophene components and that polythiophene compounds …
High-voltage measurements on the 5 ppm relative uncertainty level with collinear laser spectroscopy
2018
We present the results of high-voltage collinear laser spectroscopy measurements on the 5 ppm relative uncertainty level using a pump and probe scheme at the transition of involving the metastable state. With two-stage laser interaction and a reference measurement we can eliminate systematic effects such as differences in the contact potentials due to different electrode materials and thermoelectric voltages, and the unknown starting potential of the ions in the ion source. Voltage measurements were performed between −5 kV and −19 kV and parallel measurements with stable high-voltage dividers calibrated to 5 ppm relative uncertainty were used as a reference. Our measurements are compatible …
Graphene electrochemical responses sense surroundings
2012
Abstract Graphite oxide (GO) paper, obtained by direct filtration of exfoliated GO in water over PTFE membrane filters, was reduced by using hydrazine vapours. The graphene-paper thus obtained was characterized by the combination of different techniques. The electrochemical characterization by cyclic voltammetry, chronoamperometry and chronopotentiometry presents a strong influence of the working conditions: temperature, electrolyte concentration and current on the electrochemical responses, indicating a good ability of the material to sense ambient and working conditions. Electrochemical devices based on graphene are expected to work as dual, and simultaneous, sensing-actuators.
Metal thin-film temperature sensor embedded in heat-sink for CPV cells characterization
2014
The efficiency of a photovoltaic cell is dependent on its temperature, for this reason an accurate measurement of this parameter is important to fully characterize the device and to optimize its performance. For CPV applications a significant heat flux is needed to remove excess heat from the cell towards a heat sink, making it difficult to derive the cell temperature. In fact, measurements performed directly between the cell and the heat-sink, by use of commercial bulk sensors, would produce a significant disturbance in the heat flow; on the other hand, a measurement performed out of the cell / heat sink axis would be subject to large uncertainties, due to the high radial temperature gradi…
A critical approach to the toxic metal ion removal by hazelnut and almond shells
2018
The adsorption capacity of ground hazelnut (HS) and almond (AS) shells towards Pb(II) and Cd(II) has been studied at pH = 5, in NaNO3 and NaCl ionic media, in the ionic strength range 0.05-0.5 mol L-1. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry technique to check the amount of the metal ion removed by HS and AS materials. Different kinetic and equilibrium equations were used to fit experimental data and a statistical study was done to establish the suitable model for the data fitting. A speciation study of the metal ions in solution was also done in order to evaluate the influence of the ionic medium on the adsorption pr…