Search results for "electrode"

Operating Modes of Sandwiched Light-Emitting Electrochemical Cells

2011

Light-emitting electrochemical cells (LECs) are promising lighting devices in which the redistribution of ionic charges allows for double electronic carrier injection from air-stable electrodes. Uncertainties about the mode of operation are limiting the progress of these devices. Using fast (with respect to the current growth time) but resolutive electrical measurement techniques, the electronic transport mechanism in state-of-the-art sandwiched devices can be monitored as a function of the operation time. The results indicate the formation of doped transport layers adjacent to the electrodes that reduces the extent of the central neutral light-emitting layer where electronic transport is l…

Thermogalvanic corrosion of Alloy 31 in different heavy brine LiBr solutions

2012

Thermogalvanic corrosion generated between two electrodes of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated imposing different temperature gradients in three deaerated LiBr solutions, under open circuit conditions by using a zero-resistance ammeter (ZRA). Besides EIS spectra were acquired in order to explain the obtained results. On the whole, cold Alloy 31 electrodes were anodic to hot Alloy 31 electrodes, since an increase in temperature favoured the cathodic behaviour of the hot electrode. Thermogalvanic corrosion of Alloy 31 in the LiBr solutions studied was not severe, although it negatively affects the corrosion resistance of the cold anode. …

Highly activated screen-printed carbon electrodes by electrochemical treatment with hydrogen peroxide

2018

An easy effective method for the activation of commercial screen-printed carbon electrodes (SPCEs) using H2O2 is presented to enhance sensing performances of carbon ink. Electrochemical activation consists of 25 repetitive voltammetric cycles at 10 mV s−1 using 10 mM H2O2 in phosphate buffer (pH 7). This treatment allowed us to reach a sensitivity of 0.24 ± 0.01 μA μM−1 cm−2 for the electroanalysis of H2O2, which is 140-fold higher than that of untreated SPCEs and 6-fold more than screen-printed platinum electrodes (SPPtEs). Electrode surface properties were characterized by SEM, EIS and XPS. The results revealed atomic level changes at the electrode surface, with the introduction of new ca…

Ascorbic Acid determination using linear sweep voltammetry on flexible electrode modified with gold nanoparticles and reduced graphene oxide

2020

Indium tin oxide (ITO) coated on flexible polyethylene terephthalate (PET) substrate electrode was modified with reduced graphene oxide and gold nanoparticles by simple co-electrodeposition performed at -0.8 V vs SCE for 200 s. All samples were characterized by electron scan microscopy. The as prepared electrode was used as electrochemical sensor to selective detection of ascorbic acid using linear sweep voltammetry. Excellent results were obtained in a linear range from 20 to 150 µM of ascorbic acid with a limit of detection of about 3.1 µM (S/N=3.3). The sensors have a reproducibility of about 5.5% and also show high selectivity towards different interferents such as chlorine, calcium, ma…

Electrochemical Impedance Spectra of Particulate Matter and Smoke

2011

Particularly aerosol particles of fine dimensions are recognized to have a strong impact on the climate change, on the atmospheric energy budget, on the environment and on human health. In this study coarse aerosol particles with different black carbon mass concentrations were investigated by electrochemical impedance spectroscopy. Present work describes preparation of particulate matter samples for impedance measurements, the principles of the structure of electrochemical cell and the relationship between parameters obtained from impedance spectra and black carbon mass concentration. Using complex electrode it is possible to obtain qualitative impedance spectra of particulate matter which …

Nanostructured Electrodes For Biosensing: An Innovative Technology With Huge Potential Applications

2019

One-Step Electrodeposition of CZTS for Solar Cell Absorber Layer

2015

CZTS thin films were obtained by one-step electrochemical deposition from aqueoussolution at room temperature. Films were deposited on two different substrates, ITOon PET, and electropolished Mo. Differently from previous studies focusing exclu‐sively on the formation of kesterite (Cu4ZnSnS4), here, the synthesis of a phase withthis exact composition was not considered as the unique objective. Really, startingfrom different baths, amorphous semiconducting layers containing copper–zinc–tin–sulphur with atomic fraction Cu0.592Zn0.124Sn0.063S0.221 and Cu0.415Zn0.061Sn0.349S0.175, werepotentiostatically deposited. Due to the amorphous nature, it was not possible to de‐tect if one or more phases…

Improvement in the performance of low temperature H2-O2 fuel cell with chitosanephosphotungstic acid composite membranes

2016

Abstract Free-standing chitosan/phosphotungstic acid polyelectrolyte membranes, prepared by ionotropic gelation on alumina porous supports, were employed as proton conductor in low temperature H 2 –O 2 fuel cell. A drying step on glass substrate was introduced in the fabrication procedure to reduce shrinkage and consequent corrugation. Membranes were tested with electrodes prepared according to different procedures and with two different Pt loadings, namely 0.5 and 1 mg cm −2 . Both the investigated kinds of electrodes allowed to get very promising power peaks of 550 mW cm −2 in spite of the different Pt content. The polarization curves and the electrochemical impedance spectra suggest that…

Trapping of 27 bp–8 kbp DNA and immobilization of thiol-modified DNA using dielectrophoresis

2006

Dielectrophoretic trapping of six different DNA fragments, sizes varying from the 27 to 8416 bp, has been studied using confocal microscopy. The effect of the DNA length and the size of the constriction between nanoscale fingertip electrodes on the trapping efficiency have been investigated. Using finite element method simulations in conjunction with the analysis of the experimental data, the polarizabilities of the different size DNA fragments have been calculated for different frequencies. Also the immobilization of trapped hexanethiol- and DTPA-modified 140 nm long DNA to the end of gold nanoelectrodes was experimentally quantified and the observations were supported by density functiona…

Ni alloy nanowires as high efficiency electrode materials for alkaline electrolysers

2021

Abstract The fabrication and characterization of nickel-alloy electrodes for alkaline electrolysers is reported. Three different alloys (Ni–Co, Ni–Zn and Ni–W) at different composition were studied in order to determine the optimum condition. Nanostructured electrodes were obtained by template electrodeposition into a nanoporous membrane, starting from aqueous solution containing the two elements of the alloy at different concentrations. Composition of alloys can be tuned by electrolyte composition and also depends on the difference of the redox potential of elements and on the presence of complexing agents in deposition bath. Electrochemical and electrocatalytic tests, aimed at establishin…