10 research outputs found
Electrodeposition of transition metals from highly concentrated solutions of ionic liquids
No full textFive different ionic liquids (ILs), obtained by dissolving bistriflimide salts of Ag, Cu, Co, Ni and zinc in 1-butyl-3-methylimidazolium bistriflimide ([bmim][Tf2N]) were synthesized and electrochemically characterized by means of cyclic voltammetry and chronoamperometry. Silver-bearing IL represents the simplest electrochemical system since silver is present as uncoordinated or weakly coordinated Ag+ ions. Homogeneous and crack-free silver coatings were potentiostatically obtained from this ionic liquid and the nucleation and growth mechanism were determined. In contrast, copper-cobalt- and zinc-bearing systems were highly moisture sensitive. The presence of large amounts of water changes the nature of the coordination species present in the solution, facilitating the electroreduction of the metal complexes. However, in hydrated solutions we observe simultaneous hydrogen evolution, which impairs the electrochemical investigation of the metal nucleation and growth mechanism. Nevertheless, metallic deposits were obtained and their morphologies investigated as a function of the deposition potential and water content. Conversely, within the investigated electrochemical window, the Ni-bearing IL does not form electroactive species
Verso l'ingegnerizzazione di un sensore elettrochimico combinato per il monitoraggio in continuo del tenore di ioni cloruro e della conduttività elettrica di acque potabili
No full textElectrodeposition of transition metals from highly concentrated solutions of ionic liquids
No full textLow-Cost Potentiometric Sensor for Chloride Measurement in Continuous Industrial Process Control
No full textLow-Cost Potentiometric Sensor for Chloride Measurement in Continuous Industrial Process Control
No full textRecently, the new updates in legislation about drinking water control and human health have increased the demand for novel electrochemical low-cost sensors, such as potentiometric ones. Nowadays, the determination of chloride ion in aqueous solutions has attracted great attention in several fields, from industrial processes to drinking water control. Indeed, chloride plays a crucial role in corrosion, also influencing the final taste of beverages, especially coffee. The main goal is to obtain devices suitable for continuous and real-time analysis. For these reasons, we investigated the possibility to develop an easy, low-cost potentiometric chloride sensor, able to perform analysis in aqueous mediums for long immersion time and reducing the need of periodic calibration. We realized a chloride ion selective electrode made of Ag/AgCl sintered pellet and we tested its response in model solutions compatible with drinking water. The sensor was able to produce a stable, reproducible, and accurate quantification of chloride in 900 s, without the need for a preliminary calibration test. This opens the route to potential applications of this sensor in continuous, in situ, and real time measurement of chloride ions in industrial processes, with a reduced need for periodic maintenance
Corrosion Resistance Test of Electroplated Gold and Palladium Using Fast Electrochemical Analysis
No full textNoble metal coatings are commonly employed to improve corrosion resistance of metals in the electronic and jewellery industry. The corrosion resistance of electroplated goods is currently determinate with long, destructive and almost subjective interpretation corrosion tests in artificial atmosphere. In this study we present the application of electrochemical analysis to obtain fast and numerical information of the antiaging coating. We performed open circuit potential (OCP) and corrosion current measurement; we employed also the electrochemical impedance spectroscopy (EIS), commonly applied to organic or passivated metal with high-impedance, to find the best option for noble low-impedance coating analysis. For comparison, traditional standardized tests (damp heat ISO 17228, salt spray ISO 9227 and sulphur dioxide ISO 4524) were also performed
Corrosion Resistance Test of Electroplated Metals using Fast Electrochemical Non-Destructive Analysis
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On the Electrochemical Growth of a Crystalline p‐n Junction From Aqueous Solutions
No full textOur society largely relies on inorganic semiconductor devices which are, so far, fabricated using expensive and complex processes requiring ultra-high vacuum equipment. Here we report on the possibility of growing a p–n junction taking advantage of electrochemical processes based on the use of aqueous solutions. The growth of the junction has been carried out using the Electrochemical Atomic Layer Deposition (E-ALD) technique, which allowed to sequentially deposit two different semiconductors, CdS and Cu2S, on an Ag(111) substrate, in a single procedure. The growth process was monitored in situ by Surface X-Ray Diffraction (SXRD) and resulted in the fabrication of a thin double-layer structure with a high degree of crystallographic order and a well-defined interface. The high-performance electrical characteristics of the device were analysed ex-situ and show the characteristic feature of a diode
On the Contrasting Effect Exerted by a Thin Layer of CdS against the Passivation of Silver Electrodes Coated with Thiols
No full textThe passivation of metal electrodes covered by self-assembled monolayers of long-chain thiols is well known. The disappearance of the voltammetric peak of redox species in solution is a classical test for the formation of full layers of thiols. Similar studies on semiconductors are still very limited. We used silver surfaces covered by an ultrathin layer of CdS as substrate for self-assembling of n-hexadecanethiol (C16SH), and we compared the experimental results with those obtained by using the bare silver surface as substrate. The strong insulating effect of C16SH deposited on Ag(III) is shown by the inhibition of the voltammetric peak of Ru(NH3)63+/2+. On the contrary, the voltammogram obtained on CdS-covered Ag(III) is very similar to that obtained on the bare Ag(III) electrode, thus suggesting that the presence of CdS exerts a contrasting effect on the passivation of the silver electrode. A crucial point of our work is to demonstrate the effective formation of C16SH monolayers on Ag(III) covered by CdS. The formation of full layers of C16SH was strongly suggested by the inhibition of the stripping peak of Cd from the CdS deposit covered by C16SH. The presence of C16SH was confirmed by electrochemical quartz crystal microbalance (EQCM) measurements as well as by Auger electron spectroscopy (AES) analysis
