1,721,221 research outputs found
Nanomaterials for the development of electrochemical sensors
No full textSome electrochemical sensors fabricated at the Department of Industrial Chemistry are described in order to highlight the potentialities of nanotechnologies in the field of sensing. Electrochemical deposition is the elective technique for the modification of conductive substrates. In particular, the nanomaterials exploited for the development of sensors are conductive or molecularly imprinted polymers, silver nanoparticles and a composite made of carbon nanotubes and reduced graphene oxide. The reported applications are related to the food field
Electrochemical characterisatio n of electrodes modified with a Co/Al hydrotalcite-like compound
No full texttechniques and electrochemical impedance spectroscopy in aqueous solution. The latter technique was used in order to study the electronic
and ionic transport, both inside and on the surface of the material. The behaviour of the modified electrode was studied at different OH−
concentrations (pH 11–12.8) and at different temperatures, with the aim to calculate the activation energies of the electronic conduction and
charge-transfer processes.
The electronic conductivity of the bulk material is dependent on the CoIII/CoII ratio and results the limiting parameter of the overall redox
process. The same result was previously obtained for the Ni based hydrotalcite, but the latter material showed a better electrical conductivity
Electrocatalytic determination of thiols using hybrid Copper Cobalt Hexacyanoferrate modified glassy carbon electrode
No full textAn electrochemical sensor based on a glassy carbon electrode (GCE) modified by a thin film of hybrid copper cobalt hexacyanoferrate (Cu-CoHCF) was prepared and tested for the determination of three thiols: l-cysteine (CySH), l-glutathione (GSH) and 1,4-butanedithiol (BdSH). Cyclic voltammetry (CV) measurements were carried out with the as prepared and thermally treated chemically modified electrode (CME) in phosphate buffer solution from pH 2 to 7. From the CV measurements, it was concluded that at pH higher than 5, the Cu-CoHCF layer was unstable and underwent significant fouling when biased at a potential at which the three thiols were electrocatalically oxidized. Following the preliminary CVs chronoamperometric measurements were carried out to determine the optimum conditions to develop an analytical method for the determination of thiols. Cysteine showed the lowest limit of detection (7.5 × 10-7 M), but very low values were displayed also by GSH (2.5 × 10-6 M) and BdSH (2.0 × 10-6 M). The range of linearity extended up to 6.0 × 10-5 M for CySH, 9.0 × 10-5 M for GSH and 1.2 × 10-4 M for BdSH without significant fouling of the CME. The analytical method was applied to the determination of GSH in a nutraceutical purchased from the local market. © 2015 Elsevier B.V. All rights reserved
Iron vs Aluminum Based Layered Double Hydroxides as Water Splitting Catalysts
No full textThis paper describes the electrosynthesis, characterization and electrocatalytic properties towards oxygen evolution reaction (OER) of four layered double hydroxides (LDHs) containing cobalt or nickel as divalent cation and aluminum or iron as trivalent metal. The electrochemical behaviour of the LDH modified electrodes was studied by cyclic voltammetry (CV), and the LDHs were characterized by XRD and SEM/EDS. Two materials, i.e.; platinum and glassy carbon (GC), were investigated as electrode supports recording polarization and chronopotentiometric curves, with a rotating disk electrode in alkaline solutions. LDHs containing iron exhibited higher activity for OER and all the materials showed a good stability and durability in alkaline media. When GC was used as electrode support the performances of the OER catalysts resulted to be even better than those exhibited by the same LDHs electrodeposited on Pt
Beyond the iron-dithiolate mimics paradigm: diiron complexes with m-carbyne ligands as electrocatalyst for proton reduction
No full textGLASSY CARBON MODIFIED ELECTRODES WITH LAYERED DOUBLE HYDROXIDES FOR THE OXYGEN EVOLUTION REACTION
No full textGlassy carbon electrodes (GCE) were modified with a thin film of Ni/Al and Ni/Fe Layered Double Hydroxides (LDHs). The LDHs were chemically synthesized, by the double-microemulsion method according to literature data1. That modified electrodes were found to be active towards the oxygen evolution reaction (OER). The OER activity of LDHs modified electrodes was investigated in 0,1 M NaOH, at a slow scan rate of 5 mV/s, between 0 V and the OER onset potential (Ag/AgCl/3 M was used as reference electrode). During the measurements the working electrode was rotating at 1600 rpm to remove the generated oxygen bubbles from it surface. The electrochemical characterization of the Ni/Al and Ni/Fe-LDHs evidenced that the OER onset potential of those modified electrodes occurred respectively at +0.55 V and +0.53 V, showing a considerably reduced potential, compared to the values recorded in the same conditions with the bare GCE or GCE modified with a film of not redox active Mg/Al and Mg/Fe-LDHs (onset of OER current at ~1.20 V). A similar behaviour to the chemically synthesized active catalysts, was observed for the ones electrochemically synthesized from a solution of Ni(NO3)2 and Fe(NO3)3 or Al(NO3)3 (molar ratio 3:1), by applying an anodic potential of -0,9 V for 90 seconds. Furthermore the active LDHs exhibited a good stability in alkaline solution, since the chronopotentiometry curves, recorded applying a current density of 2,5 mA/cm2 for five minutes, showed that the catalysts had a nearly constant operating potential
Diiron Complexes with Bridging Hydrocarbyl Ligands as Electrocatalysts for Proton Reduction
No full textAnalytical performances of Ni LDH films electrochemically deposited on Pt surface: phenol and glucose detection
No full textNi/Al Layered Double Hydroxide thin films have been prepared by electochemical deposition on Pt electrodesNi/Al Layered Double Hydroxide (LDH) thin films have been prepared by electrochemical deposition on Pt electrodes, with the aim to study the performances of the coated electrodes as sensors for phenol and glucose detection. The electrochemical behavior of the devices has been assessed and the adhesion of the coatings evaluated since this parameter plays an important role for the long term performance of the sensor. In particular adhesion has been studied as a function of the Pt surface features which depend on the electrode pretreatment
Electrochemical Deposition of Nanomaterials for Electrochemical Sensing
No full textThe most commonly used methods to electrodeposit nanomaterials on conductive supports or to obtain electrosynthesis nanomaterials are described. Au, layered double hydroxides (LDHs), metal oxides, and polymers are the classes of compounds taken into account. The electrochemical approach for the synthesis allows one to obtain nanostructures with well-defined morphologies, even without the use of a template, and of variable sizes simply by controlling the experimental synthesis conditions. In fact, parameters such as current density, applied potential (constant, pulsed or ramp) and duration of the synthesis play a key role in determining the shape and size of the resulting nanostructures. This review aims to describe the most recent applications in the field of electrochemical sensors of the considered nanomaterials and special attention is devoted to the analytical figures of merit of the devices
- …
