Electrochemical characterization of polyaniline electrode for use in electrochemical power sources

Polyaniline (PANI) electrode was formed by electrochemical synthesis on graphite under galvanostatic condition at current density of 2.0 mA cm-2 from aqueous solution of 1.0 mol dm-3 HCl and 0.25 mol dm-3 aniline. Electrochemical characterization of the PANI electrode was performed in 0.5 mol dm-3 HCl using cyclic voltammetry and galvanostatic measurements. The overall charge capacity of the PANI electrode was estimated to be 0.154 mA h cm-2, corresponding to 25 % of the theoretical mass of PANI available for the dopant exchange. It was observed that during initial cyclization at low pH, the extent of PANI degradation products was insignificant and practically had no influence on the charge/discharge characteristics of the PANI electrode

Characteristics of polyaniline lead - dioxide power sources

Polyaniline (PANI) anode, electrochemically synthesized on graphite electrode from sulfuric acid solution, and electrochemically formed thin film lead dioxide cathode, were investigated for possible applications as electrode materials in PANI | H2SO4 | PbO2 aqueous based rechargeable power sources. The stimulation of charge/discharge characteristics of the cell, based on half cell reactions investigations, was evaluated. Charging of the cell would occur in the voltage range of 1.2 and 1.7 V, while discharge would occur in the range of 1.3 and 1 V

Korozija zavarenog spoja austenitnog i feritnog nerđajućeg čelika

Dissimilar metal connections are prone to frequent failures. These failures are attributed to the difference in the mechanical properties across the weld, the coefficients of thermal expansion of the two types of steels and the resulting creep at the interface. For the weld analyzed in this research, it was shown that corrosion measurements can be used for a proper evaluation of the quality of weld material and for the prediction of whether or not the material, after the applied welding process, can be in service without failures. It was found that the corrosion of the weld analyzed in this research resulted from the simultaneous activity of different types of corrosion. In this study, electrochemical techniques including polarization and metallographic analysis were used to analyze the corrosion of a weld material of ferrite and austenitic stainless steels. Based on surface, chemical and electrochemical analyses, it was concluded that corrosion occurrence was the result of the simultaneous activity of contact corrosion (ferrite and austenitic material conjuction), stress corrosion (originating from deformed ferrite structure) and inter-granular corrosion (due to chromium carbide precipitation). The value of corrosion potential of -0.53 V shows that this weld, after the thermal treatment, is not able to repassivate a protective oxide film.Spojevi različitih metala dobijenih zavarivanjem skloni su propadanju uglavnom usled pojave različitih vidova korozije. Fizičko-hemijska, mehanička svojstva, kao i koeficijenti toplotnog širenja različitih čelika najčešći su uzrok pucanja materijala na zavarenim spojevima. Istraživanja u ovom radu su pokazala da se ispitivanje korozije materijala može koristiti za procenu kvaliteta spojeva zavarenih materijala. Različite analitičke, metalografske i elektrohemijske tehnike i metode analize su primenjene za ispitivanje korozije zavarenog spoja nerđajućih čelika feritne i austenitne strukture. Ustanovljeno je da do pojave korozije na zavarenom spoju ispitivanih materijala prevashodno dolazi usled: kontaktne korozije, naponske korozije (koja potiče od deformisane strukture ferita) i međukristalne korozije (posledica izluživanja hrom-karbida) u feritnom delu zavarenog spoja

Electrochemical Polymerization of Aniline

In recent years, great focus has been placed upon polymer thin films. These polymer thin films are important in many technological applications, ranging from coatings and adhesives to organic electronic devices, including sensors and detectors. Electrochemical polymerization is preferable, especially if the polymeric product is intended for use as polymer thin films, because electrogeneration allows fine control over the film thickness, an important parameter for fabrication of devices. Moreover, it was demonstrated that it is possible to modify the material properties by parameter control of the electrodeposition process. Electrochemistry is an excellent tool, not only for synthesis, but also for characterization and application of various types of materials. This book provides a timely overview of a current state of knowledge regarding the use of electropolymerization for new materials preparation, including conducting polymers and various possibilities of applications

Characteristics of polyaniline lead - dioxide power sources

Polyaniline (PANI) anode, electrochemically synthesized on graphite electrode from sulfuric acid solution, and electrochemically formed thin film lead dioxide cathode, were investigated for possible applications as electrode materials in PANI | H2SO4 | PbO2 aqueous based rechargeable power sources. The stimulation of charge/discharge characteristics of the cell, based on half cell reactions investigations, was evaluated. Charging of the cell would occur in the voltage range of 1.2 and 1.7 V, while discharge would occur in the range of 1.3 and 1 V

Electrochemical characterization of polyaniline electrode for use in electrochemical power sources

Polyaniline (PANI) electrode was formed by electrochemical synthesis on graphite under galvanostatic condition at current density of 2.0 mA cm-2 from aqueous solution of 1.0 mol dm-3 HCl and 0.25 mol dm-3 aniline. Electrochemical characterization of the PANI electrode was performed in 0.5 mol dm-3 HCl using cyclic voltammetry and galvanostatic measurements. The overall charge capacity of the PANI electrode was estimated to be 0.154 mA h cm-2, corresponding to 25 % of the theoretical mass of PANI available for the dopant exchange. It was observed that during initial cyclization at low pH, the extent of PANI degradation products was insignificant and practically had no influence on the charge/discharge characteristics of the PANI electrode

Electrochemical determination of ascorbic acid using electrochemically deposited polyaniline

Electroconducting polymers are promising materials to be used in various fields including: batteries, capacitors, electronic devices, corrosion, biosensors and sensors[1,6]. Polyaniline is probably the most investigated electroconducting polymer, due to low cost monomer, conductivity, environmental stability. Polyaniline can be obtained by chemical or electrochemical oxidative polymerization of aniline. Electrochemical synthesis is performed in anodic process directly from acidic aqueous electrolyte containing aniline. Polyaniline can be used as electrode material for electrochemical determination of ascorbic acid based on electrocatalytic oxidation of ascorbic acid

Electrochemical Water Treatment Devices

Paper published in 43rd International October Conference on Mining and Metallurgy - IOC 2011, October 12-15, 2011, Kladovo, Serbia: Proceedings, Bor : Technical Faculty, 2011

Površinska modifikacija platine zlatom i zlata platinom i njen uticaj na reakcije izdvajanja vodonika i redukcije kiseonika

Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal-chloride complexes using cyclic voltammeter. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER) and oxygen reduction (ORR) reactions. Aplatinum overlayer on a gold substrate increases the activity for HER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.Površinska modifikacija platine zlatom i zlata platinom je izvršena iz rastvora sumporne kiseline i odgovarajućih hloridnih kompleksa metala primenom ciklične voltametrije. Poređenjem količine naelektrisanja u oblasti potpotencijalne depozicije vodonika i odgovarajućih oblasti redukcije oskida čistih i modifikovanih elektroda zaključeno je da platina na zlatu formira 3D, a zlato na platini 2D ostrva. Aktivnosti ovako modifikovanih površina za reakcije izdvajanja vodonika i redukcije kiseonika u rastvoru sumporne kiseline poređene sa aktivnostima čistih metala. Elektroda od zlata modifikovana platinom značajno uvećava aktivnost za obe ispitivane rekacije u poređenju sa čistim zlatom. Sa druge strane, elektroda od platine modifikovana zlatom ima neznatno manju aktivnost u poređenju sa čistom platinom. Zbog ograničenih resursa i visoke cene platine platina modifikovana zlatom može biti zamena za čistu platinu kao dobar katalizator za reakciju redukcije kiseonika, posebno u gorivim spregovima u oblasti niskih temperatura

Uticaj gustine struje izmene na proces taloženja tankih filmova metala na nesrodnim podlogama

The initial stage of thin surface metal film formation on inert substrate is considered. The simultaneous action of both active centers and nucleation exclusion zones was taken into consideration when discussing the saturation nucleation exclusion zones was taken into consideration when discussing the saturation nucleus density. The saturation nucleus density increases with increasing number of active centers and decreasing the radii of nucleation exclusion zones (enhancing the thin metal film formation). Atone at the same deposition current density deposition overpotential increases with decreasing deposition process exchange current density, leading to the increase in the number of active centers and to decrease of crystallization overpotential and radii of nucleation exclusion zones. Because of this compact surface metal film will be formed at a lower quantity of electrodeposited metal with a decrease in exchange current density.Razmatrana je početna faza nastajanja površinskog filma metala. Diskutovan je uticaj aktivnih centara i zona isključenja nukleacije na zasićenu gustinu nukleusa. Zasićena gustina nukleusa raste sa porastom broja aktivnih centara i sa smanjenjem poluprečnika zona isključenja nukleacije, što simuliše nastajanje tankog filma metala. Pri jednoj gustini struje taloženja prenapetost raste sa smanjenjem gustine struje izmene za proces taloženja, što dovodi do povećanja broja aktivnih centara i smanjenja kristalizacione prenapetosti i poluprečnika zona isključenja. Na taj način se formiraju kompaktni površinski filmovi pri taloženju manje količine metala kada je proces taloženja okarakterisan manjom vrednošću gustine struje izmene