http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Tue, 02 Apr 2013 15:08:13 +0000 http://www.hindawi.com/isrn/electrochem/2013/142493/ This study presents electrochemical data concerning the aluminium alloy AA7075 surface modified by self-assembled monolayers (SAMs) of octadecyl-trimethoxy-silane and propyl-trimethoxy-silane. Polarisation curves have shown SAMs blocking effect, as they partially block the oxygen reduction reaction and displace the corrosion potential to positive values. Electrochemical impedance spectroscopy experiments have suggested that the protective effect comes from the oxide layer stabilization by the organic monolayers, which block the corroding species diffusion to the surface. These results show the potential of using methoxy-silanes SAMs as corrosion protective coatings; however, they are also indicative of the superior octadecyl-trimethoxy-silane protective characteristics. Rodrigo S. Neves, Daiane P. B. Silva, and Artur J. Motheo Copyright © 2013 Rodrigo S. Neves et al. All rights reserved. Sun, 31 Mar 2013 13:48:44 +0000 http://www.hindawi.com/isrn/electrochem/2013/403542/ The inhibition of the corrosion of mild steel in 1 M H2SO4 solution by the pharmaceutically active compound esomeprazole (ESP) has been investigated by using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements. The effect of temperature on the corrosion behavior with the addition of different concentrations of ESP was studied in the temperature range of 30–60°C. Results obtained revealed that the inhibition efficiency increased with the increase in concentration of the inhibitor but decreased with the increase in temperature. The addition of KI increased the inhibition of ESP to a considerable extent. The experimental results suggest that the presence of iodide ions in the solution stabilized the adsorption of the ESP molecule on the mild steel surface, thereby improving the inhibition efficiency. Polarization curves indicated that the ESP belonged to a mixed-type inhibitor. Adsorption of the inhibitor on the mild steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. Surface analysis via scanning electron microscope (SEM) and atomic force microscope (AFM) shows a significant improvement in the surface morphology of the mild steel plate. G. Karthik and M. Sundaravadivelu Copyright © 2013 G. Karthik and M. Sundaravadivelu. All rights reserved. Tue, 12 Mar 2013 17:29:34 +0000 http://www.hindawi.com/isrn/electrochem/2013/732815/ Although the pulse-current electrodeposition method is a commonly used technique, it has not been widely employed in electrode preparation. This method was applied to sintered nickel electrodes in a nickel salt solution containing additives. The active material that was obtained, nickel hydroxide, was studied using different characterization techniques. Electrodes impregnated with pulse current had higher capacity than those impregnated with continuous current. The active material is homogeneous and compact with optimum loading and good performance during discharge. These characteristics would provide a large amount of energy in a short time due to an increase in the electrode kinetic reaction. M. D. Becker, G. N. Garaventta, and A. Visintin Copyright © 2013 M. D. Becker et al. All rights reserved. Tue, 12 Feb 2013 18:43:01 +0000 http://www.hindawi.com/isrn/electrochem/2013/959128/ Electrochemical behavior of five progressively alkylated thiazine dyes has been investigated at glassy carbon/montmorillonite and glassy carbon/zeolite electrodes. Quantitative characteristics, associated with the positions of peak potentials ( and ) and current ratios (), are measured with scan rates. The peak current observed in the modified electrodes is dependent on both the porosity and nature and number of sites involved in partitioning the complex into film. The values of diffusion coefficient for different dyes have been calculated from electrochemical data. It is suggested that in clay-modified electrode along with physical diffusion the process of electron hopping seems to be most likely. Amitabha Chakraborty, Shamsuzzaman Ahamed, Subrata Pal, and Swapan K. Saha Copyright © 2013 Amitabha Chakraborty et al. All rights reserved. Mon, 11 Feb 2013 15:46:24 +0000 http://www.hindawi.com/isrn/electrochem/2013/240571/ The ionic conductivity and viscous flow data of , , have been collected in a large temperature range, below and above their glass transition temperatures (). A microscopic model is proposed, assuming that the ionic displacement would result from the migration of interstitial positively charged cationic pairs whose concentration is an activated function of temperature. Below , their migration is also an activated mechanism, but a “free volume” would prevail above this temperature. This discontinuity in the migration mechanism justifies a Dienes-Macedo-Litovitz (DML) relationship to be representative of conductivity data above and an Arrhenius law below. According to this model, the enthalpy deduced by the fit of high temperature data using a DML equation would correspond to the charge carrier formation, whose migration enthalpy, below , could be deduced by the difference between the activation energy measured in the Arrhenius domain and the charge carrier formation enthalpy. To reduce the number of adjustable parameters numerical values were physically justified. We also applied a complete test for conductivity below , using the so-called weak electrolyte model, splitting activation enthalpy into formation and migration enthalpies and also explaining the variation of pre-exponential term of conductivity with composition. Marcio Luis Ferreira Nascimento Copyright © 2013 Marcio Luis Ferreira Nascimento. All rights reserved. Sun, 03 Feb 2013 13:39:11 +0000 http://www.hindawi.com/isrn/electrochem/2013/486050/ Nickel-based nanocomposite coatings were prepared from a Watts-type electrolyte containing reinforcement’s particles (silicon carbide and graphite) to deposit onto the steel St-37 substrate. The electrochemical plating of the coatings in absence and presence of surfactants and reinforcements particles was carried out to optimize high quality coatings with appropriate mechanical and morphological features. The surfactants such as cetyltrimethylammonium bromide (CTAB), sodyumdodecyl sulfate (SDS), and saccharine affected electrodeposition plating and subsequently changed mechanical characteristics. Based on XRD results, the dominant phases in the absence of surfactants were nickel oxide (NiO), nickel, and silicon carbide (SiC), while the main phases in presence of surfactants were nickel (Ni) and SiC. The hardness of the resultant coatings was found to be from 332 to 593 (Hv) depending on the bath parameter and the reinforcements weight percentage (wt%) in the Ni matrix. Microscopic observations illustrated a cluster-like structure which consisted of some fine sphere particulates with average particle size of 65–150 nm. According to elemental mapping spectra, a homogenous distribution of nickel, silicon, and carbon particles appeared into the nickel matrix coating. Finally, the experimental outcomes demonstrated that the surfactants have significant influence on the composition of coatings, surface morphology, and mechanical properties. Abbas Fahami, Bahman Nasiri-Tabrizi, Mohsen Rostami, and Reza Ebrahimi-Kahrizsangi Copyright © 2013 Abbas Fahami et al. All rights reserved. Thu, 31 Jan 2013 07:51:23 +0000 http://www.hindawi.com/isrn/electrochem/2013/624163/ The early stages of Co deposition on a silver electrode in ammonia medium were studied using cyclic voltammetry and chronoamperometry coupled with quartz crystal microbalance (EQCM) in ammonia solution. The results obtained by means of EQCM showed that during the initial stages of cobalt deposition a monolayer is formed on the substrate both in the underpotential and overpotential region, and this monolayer is formed at −600 mV and −980 mV. Once the cobalt deposition process starts, the growth is very fast making the investigation of the initial stages rather difficult. During this process, cobalt atoms transfer their two electrons through free species and not through cobalt hydroxide species adsorbed on the electrode as CoOH+ or Co(OH)2. In addition, it has been found that at potentials more positive than −600 mV, ammonia adsorption takes place on the substrate surface, and theses species are replaced when the cobalt atoms arrive at potentials more negative than −600 mV. A. Montes-Rojas and A. L. Donjuan-Medrano Copyright © 2013 A. Montes-Rojas and A. L. Donjuan-Medrano. All rights reserved. Mon, 28 Jan 2013 08:20:26 +0000 http://www.hindawi.com/isrn/electrochem/2013/851921/ LiMnPO4 is anticipated to be a promising cathode material for next generation lithium battery. A reduction of particle size is recognized as a good strategy to improve its performance and it can be achieved by ball milling. However, the ball milling including carbon addition forms small LiMnPO4 particles with large carbon content, which leads to low volumetric energy density of electrode. In this study, carbon-coated LiMnPO4 prepared by hydrothermal route was applied to the ball milling without carbon addition. The reduction of particle size of carbon-coated LiMnPO4 was achieved by the ball milling without destroying the surface carbon layer. The ball-milled LiMnPO4 particle revealed better cathodic performance than non-milled sample. This was attributed to shortening Li ion diffusion path, improvement of structural flexibility, and large surface area of electrode due to reduction of particle size. The ball milling is attested to be a promising method to improve cathodic performance of carbon-coated LiMnPO4. Masashi Kotobuki Copyright © 2013 Masashi Kotobuki. All rights reserved. Sun, 30 Dec 2012 15:35:03 +0000 http://www.hindawi.com/isrn/electrochem/2013/256086/ The interfacial behavior of fluconazole on mild steel in 1 M HCl solution was studied by electrochemical methods, namely, polarization (Tafel Plot) and Electrochemical Impedance Spectroscopy (EIS). The surface morphology of mild steel in the presence and absence of fluconazole was studied by Atomic Force Microscopy (AFM). The results of the study showed that fluconazole reduced the corrosion rate in HCl acid solution by adsorbing on the surface of mild steel. Tafel results suggest that fluconazole behaves predominantly as an anodic inhibitor and shows greater inhibition efficiency (96%) at 0.30 mM. Thermodynamical parameters suggest that fluconazole is adsorbed on mild steel mainly by chemical mode. The EIS studies reveal the formation of a thin barrier film on mild steel surface. The AFM image of mild steel immersed in optimum concentration of fluconazole has confirmed the film formation on metal surface. T. Jebakumar Immanuel Edison and M. G. Sethuraman Copyright © 2013 T. Jebakumar Immanuel Edison and M. G. Sethuraman. All rights reserved. Thu, 27 Dec 2012 11:55:09 +0000 http://www.hindawi.com/isrn/electrochem/2013/564784/ Durability of single-walled (SWCNT) and multiwalled carbon nanotubes (MWCNT) as Pt supports was studied using two accelerated durability tests (ADTs), potential cycling and potentiostatic treatment. ADT of gas diffusion electrodes (GDEs) was once studied during the potential cycling. Pt surface area loss with increasing the potential cycling numbers for GDE using SWCNT was shown to be higher than that for GDE using MWCNT. In addition, equilibrium concentrations of dissolved Pt species from GDEs in 1.0 M H2SO4 were found to be increased with increasing the potential cycling numbers. Both findings suggest that Pt detachment from support surface plays an important role in Pt surface loss in proton exchange membrane fuel cell electrodes. ADT of GDEs was also studied following the potentiostatic treatments up to 24 h under the following conditions: argon purged, 1.0 M H2SO4, 60°C, and a constant potential of 0.9 V. The subsequent electrochemical characterization suggests that GDE that uses MWCNT/Pt is electrochemically more stable than other GDE using SWCNT/Pt. As a result of high corrosion resistance, GDE that uses MWCNT/Pt shows lower loss of Pt surface area and oxygen reduction reaction activity when used as fuel cell catalyst. The results also showed that potential cycling accelerates the rate of surface area loss. Mehdi Asgari and Elaheh Lohrasbi Copyright © 2013 Mehdi Asgari and Elaheh Lohrasbi. All rights reserved. Tue, 25 Dec 2012 15:31:57 +0000 http://www.hindawi.com/isrn/electrochem/2013/174834/ Platinum cluster formations have been investigated as a way to reduce the amount of Pt at the cathode of polymer electrolyte membrane fuel cells. One, two, and three layers of Pt (0.05 mg/cm2) sputtered directly on microporous layers of gas diffusion layers with and without interfacial carbon-Nafion layers and carbon-polytetrafluoroethylene (CPTFE) layers have been used as a cathode. Comparison with experimental results had showed that the best performance was obtained with three layers of Pt sputtered on carbon-Nafion containing 34.8 wt.% of Nafion and sputtered carbon-polytetrafluoroethylene containing 16.9 wt.% of polytetrafluoroethylene. High limiting current densities (>1.1 A/cm2) have been reached with cathode Pt loading as low as 0.05 mg/cm2. SEM imagery and cyclic voltammetry characterization have been performed to consolidate this study. High Pt utilization can be showed by this method. The factor influencing Pt utilisation in the oxygen reduction reaction is intrinsically related to Pt clusters formation and helps in enhancing the PEMFC performance with low Pt loading. Daouda Fofana, Sadesh Kumar Natarajan, Pierre Bénard, and Jean Hamelin Copyright © 2013 Daouda Fofana et al. All rights reserved.