Search results for "Industrial electrochemistry"
showing 10 items of 46 documents
Synthesis of self-standing Pd nanowires via galvanic displacement deposition
2009
This work shows that it is possible to obtain self-standing Pd nanowires into anodic alumina membranes by a simple metal displacement deposition. By using a proper arrangement, specifically designed in order to optimize the process, polycrystalline Pd nanowires were deposited from a solution containing Pd(NH3)4(NO3)2 as precursor. Morphological analysis showed the formation of perfectly aligned nanowires with a uniform diameter throughout the entire length. This last parameter was controlled by both the deposition time and the ratio between the anodic area (active metal) and the cathodic area (pore bottom). Keywords: Displacement deposition, Template synthesis, Palladium nanowires, Alumina …
Use of RGB digital video analysis to study electrochemical processes involving color changes
2017
Color changes on an electrode surface during the course of electrochemical processes were monitored by in situ digital video recording. The evolution of standard red, green and blue (sRGB) intensity channels extracted from digital images showed a close relationship with the electrochemical processes taking place. In particular, the derivative of the sRGB mean intensity with respect to time (dI−/dt) gave useful insights into the electrochemical mechanism. The standard deviation (std) of the sRGB intensity provided information about the color homogeneity of the studied region on the electrode surface. We selected poly(o-toluidine) electrochromism on a transparent electrode and anodic copper d…
Use of the electrochemical microcell technique and the SVET for monitoring pitting corrosion at MnS inclusions
2004
The purpose of this paper is to report on use of the electrochemical microcell technique and the scanning vibrating electrode technique for monitoring pitting corrosion on the same stainless steel microstructure. First, the electrochemical behaviour of sites containing a single inclusion was investigated in order to the determine both the successive steps occurring during the inclusions activation and some key-parameters such as the onset potential for MnS dissolution and the pitting potential. Then, the local current distribution around a pitting site was monitored at open circuit potential in order to locate anodic and cathodic regions and to obtain informations on the galvanic coupling b…
Room temperature electrodeposition of photoactive Cd(OH)2 nanowires
2009
Cd(OH)2 nanowires (NWs) were successfully prepared by room temperature electrogeneration of base using Cd(NO3)2 aqueous electrolyte and Anodic Alumina Membrane (AAM) as template. Cd(OH)2 films have been also deposited on tin-doped indium oxide (ITO) for comparison. SEM analysis shows high quality deposits made of closely packed nanowires (NWs) into AAM and uniform flake-like surface on ITO. XRD analysis reveals that Cd(OH)2 films on ITO are polycrystalline, while the nanowires grow along the preferential directions [100] and [110]. Photoelectrochemical measurements show that Cd(OH)2 NWs are photoactive materials with indirect and direct band gap of 2.15 and 2.75 eV, respectively. Keywords: …
Fe-N/C catalysts for oxygen reduction based on silicon carbide derived carbon
2017
This work was supported by the projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR “Nanomaterials - research and applications” (3.2.0304.12-0397) and by the Estonian Institutional Research Grant No. IUT20-13.
Application of total internal reflexion fluorescence microscopy for studying pH changes in an occluded electrochemical cell: Development of a wavegui…
2006
A device for pH mapping derived from optical sensors similar to total internal reflection fluorescence microscopy (TIRFM) has been developed for future possible applications in the field of localized corrosion. The sensing principle is the increase of the fluorescent yield of the fluorescein with the pH of the medium. The basic principle of this sensor is based on the excitation of a fluorescent silica polymer film of nanometre dimensions, deposited by sol–gel method on a waveguiding layer. The total internal reflexion conditions creates an evanescent wave which interacts with the molecules trapped in the silica layer. A conventional microscope located above the sample collects the fluoresc…
Electrical network of nanofluidic diodes in electrolyte solutions: Connectivity and coupling to electronic elements
2016
[EN] We consider a nanopore network with simple connectivity, demonstrating a two-dimensional circuit (full-wave rectifier) with ensembles of conical pores acting as nanofluidic diodes. When the bridge nanopore network is fed with an input potential signal of fluctuating polarity, a fixed output polarity is obtained. The full-wave rectification characteristics are demonstrated with square, sinusoidal, and white noise input waveforms. The charging of a load capacitor located between the two legs of the bridge demonstrates that the nanofluidic network is effectively coupled to this electronic element. These results can be relevant for energy transduction and storage procedures with nanopores …
Concatenated logic functions using nanofluidic diodes with all-electrical inputs and outputs
2018
[EN] Nanopore-based logical schemes in ionic solutions typically involve single gates and chemical inputs. The design of computer-like functions requires the consecutive concatenation of several gates and the use of electrical potentials and currents to facilitate the downstream transfer of electrochemical information. We have demonstrated the robust operation of concatenated logic functions using biomimetic nanofluidic diodes based on single pore membranes. To this end, we have implemented first the logic functions AND and OR with combinations of single nanopores using all-electrical input and output signals. The concatenation of these gates allows the output of the OR gate to act as one o…
Determination of time dependence of passive layer on nickel from instantaneous mass/charge function F(dm/dQ) in competitive passivation/dissolution c…
2006
Nickel metal deposited on gold electrodes was studied in the passivity range of potentials under potentiostatic conditions and in a weakly acid sulphate medium. Mass and current variations during electrochemical experiments were analysed with the help of the instantaneous mass/charge ratio (Fdm/dQ). This analysis allows to obtain the intensity current component associated to the formation of a passive layer of Ni(OH)2, and, in this way, the experimental thickness growth. These experimental findings have been fitted to a theoretical model based on the point defect model theory for obtaining the time dependence of the thickness of the passive layer during the first stages of growth of the pas…
Electro-generation of H2O2 and abatement of organic pollutant in water by an electro-Fenton process in a microfluidic reactor
2013
The electro-generation of H2O2 and the abatement of the model organic pollutant Acid Orange 7 (AO7) in water by an electro-Fenton process were performed both in a conventional undivided macro cell and, for the first time, in a microfluidic reactor. Under optimized operative conditions, the reduction of oxygen in the microdevice gave rise, using graphite cathode, to a concentration of H2O2 of about 6 mM, one order of magnitude higher than that achieved in conventional cells. Similarly, when electro-Fenton was performed in the microfluidic reactor a dramatic increase of the abatement of COD was achieved with respect to that obtained in a conventional cell. Keywords: Wastewater treatments, Mic…