International Journal of Electrochemistry The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Evaluation of the Synergistic Effect of Erosion-Corrosion on AISI 4330 Steel in Saline-Sand Multiphase Flow by Electrochemical and Gravimetric Techniques Tue, 17 May 2016 11:26:48 +0000 The synergistic effects of fluid flow, sand particles, and solution pH on erosion-corrosion of AISI 4330 steel alloy in saline-sand medium were studied through a rotating cylinder electrode (RCE) system by weight-loss and electrochemical measurements. The worn surface was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that, under all the test conditions assessed, the passivity of the steel alloy could not be maintained; as a result, an activation mechanism dominates the corrosion process of steel alloy. Furthermore, the potentiodynamic curves show that, with the increasing of the electrode flow rate and particle size, the anodic current density increased, which is due to deterioration of the electrode by the impacting slurry. Although the increase of particle size affects the anodic current density, the effect of particle size does not cause a significant change in the polarization behavior of the steel electrode. The electrochemical impedance and potentiodynamic curves suggest that erosion-corrosion phenomenon of the ASISI 4330 steel is under mixed control of mass transport and charge transfer. The inductive loops formed in the impedance plots are representative of an increase in roughness of the electrode caused by the particles impacting at the surface. The change in the passivity of the steel alloy as the pH is altered plays an important role in the corrosion rate. Dario Yesid Peña Ballesteros, Yelsin Enrique Mendez Camacho, and Lizeth Viviana Barreto Hernandez Copyright © 2016 Dario Yesid Peña Ballesteros et al. All rights reserved. Factors Affecting Corrosion in Gulf of Finland Brackish Water Mon, 16 May 2016 11:42:34 +0000 The Baltic Sea is a relatively shallow inland sea surrounded by the countries of North-Eastern Europe and Scandinavia. The brackish water in the Baltic Sea has low salt concentration and it is typically one-sixth of the ocean seawater. The “nominal” amount of dissolved solids, upon which formulae for artificial seawater are based, is about 34,500 ppm, of which most is sodium chloride. The major constituents are those whose concentrations are greater than 1 mg/L and are not greatly affected by biological processes. The ratio of concentrations of these ions and molecules to each other is relatively constant. Corrosion rates were determined in long-term tests in Gulf of Finland brackish water off Helsinki. The water temperature varies through the year from about 0°C in January to 15-16°C in June to August. Salinity is 4–6, highest at the end of summer and lowest when ice melts. pH is between 7.0 and 8.1. Weight loss tests from one- to four-year tests for steel, stainless steel, copper, aluminium, zinc, and galvanized steel are reported and compared to short term laboratory tests in artificial seawater. Tests for passivation rates and crevice corrosion for stainless steel are discussed in terms of environment variation. The effect of corrosion on strength of steel is also discussed. Jari Aromaa and Olof Forsén Copyright © 2016 Jari Aromaa and Olof Forsén. All rights reserved. Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys Tue, 19 Apr 2016 11:14:43 +0000 Corrosion behavior of Mg-5Y-1.5Nd alloy was investigated after heat treatment. The microstructure and precipitation were studied by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The weight loss rates of different samples were arranged as T6-24 hT6-6 hT6-14 has-castT4. The open circuit potential (OCP) showed that T4 sample had a more positive potential than that of other samples. The potentiodynamic polarization curves showed that the T6-24 h sample had the highest corrosion current density of 245.362 μAcm−2, whereas the T4 sample had the lowest at 52.164 μAcm−2. The EIS results confirmed that the heat treatment reduced the corrosion resistance for Mg-5Y-1.5Nd alloy, because the precipitations acted as the cathode of electrochemical reactions to accelerate the corrosion process. The corrosion rates of different samples were mainly determined by the amount and distribution of the precipitations. The precipitations played dual roles that depended on the amount and distribution. The presence of the phase in the alloys could deteriorate the corrosion performance as it could act as an effective galvanic cathode. Otherwise, a fine and homogeneous phase appeared to be a better anticorrosion barrier. Xiumin Ma, Quantong Jiang, Yantao Li, and BaoRong Hou Copyright © 2016 Xiumin Ma et al. All rights reserved. Electroanalytical Performance of a Carbon Paste Electrode Modified by Coffee Husks for the Quantification of Acetaminophen in Quality Control of Commercialized Pharmaceutical Tablets Sun, 03 Apr 2016 16:10:41 +0000 Electrochemical determination of acetaminophen (APAP) was successfully performed using a carbon paste electrode (CPE) modified with coffee husks (CH-CPE). Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) were, respectively, used for the morphological and elemental characterization of coffee husks prior to their utilization. The electrochemical oxidation of APAP was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). SWV technique appeared to be more sensitive since the oxidation current of APAP was twofold higher with the CH-CPE sensor than with the bare CPE, in relation to the increase in the organophilic character of the electrode surface. Furthermore, on CH-CPE, the current response of APAP varied linearly with its concentration in the range of 6.6 μM to 0.5 mM, leading to a detection limit of 0.66 μM (). Finally, the proposed CH-CPE sensor was successfully used to determine the amount of APAP in commercialized tablets (Doliprane® 500 and Doliprane 1000), with a recovery rate ranging from 98% to 103%. This novel sensor opens the way for the development of low-cost and reliable devices for the electroanalysis of pharmaceutical formulations in developing countries. Serge Foukmeniok Mbokou, Maxime Pontié, Jean-Philippe Bouchara, Francis Merlin Melataguia Tchieno, Evangeline Njanja, Assad Mogni, Pierre Yves Pontalier, and Ignas Kenfack Tonle Copyright © 2016 Serge Foukmeniok Mbokou et al. All rights reserved. Determination of Thallium(I) by Hybrid Mesoporous Silica (SBA-15) Modified Electrode Mon, 28 Mar 2016 12:08:42 +0000 Chemically modified mesoporous silica material (SBA-15) was used for the construction of Tl(I) selective carbon paste electrode. The best response was found with the electrode containing 10% modifier as electrode material. The electrode has a lower detection limit of 6.0 × 10−9 M in a working concentration range of 1.0 × 10−8–1.0 × 10−1 M. The selectivity coefficient calculated by match potential method (MPM) shows the high selectivity of electrode towards Tl(I) over other tested ions. The electrode was successfully applied as an indicator electrode for the titration of 0.01 M TlNO3 solution with standards EDTA solution and for sequential titration of mixture of different anions. Geeta Rani and Sanjay Singh Copyright © 2016 Geeta Rani and Sanjay Singh. All rights reserved. Zn Electrodeposition on Single-Crystal GaN(0001) Surface: Nucleation and Growth Mechanism Tue, 09 Feb 2016 11:38:11 +0000 The electrochemical deposition of zinc on single-crystal -type GaN(0001) from a sulphate solution has been investigated on the basis of electrochemical techniques including cyclic voltammetry, chronoamperometry, and Tafel plot. The morphology and crystal structure of zinc deposits have been characterized by means of scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The result has revealed that the deposition of Zn on GaN electrode commenced at a potential of −1.12 V versus Ag/AgCl. According to the Tafel plot, an exchange current density of ~0.132 mA cm−2 was calculated. In addition, the current transient measurements have shown that Zn deposition process followed the instantaneous nucleation in 10 mM ZnSO4 + 0.5 M Na2SO4 + 0.5 M H3BO3 (pH = 4). Fei Peng, Shuang-Jiao Qin, Yu Zhao, and Ge-Bo Pan Copyright © 2016 Fei Peng et al. All rights reserved. Shape-Controlled Synthesis of Palladium-Copper Nanoalloys with Improved Catalytic Activity for Ethanol Electrooxidation Thu, 04 Feb 2016 07:39:36 +0000 A facile solvothermal strategy is developed for the preparation of nanometer sized Pd-Cu alloy. We can control the morphology of these alloys with the use of ethylene glycol (EG) in the presence of KOH. Namely, by increasing the concentration of KOH/EG, the Pd-Cu alloys with different morphologies from near-spherical nanoparticles (NPs) to nanorods and nanowire networks have been prepared. Among all these alloys, near-spherical Pd-Cu NPs-modified electrodes exhibit the highest catalytic activity (11.7 mA/cm2) and stability toward the electrooxidation of ethanol in comparison with commercial Pd/C-modified ones (2.1 mA/cm2). Hao Wang, Weihua Yang, Qinhao Zhang, and Qingchao Qiu Copyright © 2016 Hao Wang et al. All rights reserved. Theoretical and Experimental Study of Copper Electrodeposition in a Modified Hull Cell Thu, 04 Feb 2016 06:36:01 +0000 The primary current distribution and the resistance of a modified Hull cell are calculated by using conformal mapping technique coupled with numerical evaluation of the resulting integral equations. An approximate analytical expression for the primary current distribution of a modified Hull cell is presented. The primary current distribution along the cathode surface is noticed varying in controlled manner as a function of position on the substrate. The current distributions (primary, secondary, and tertiary) in the cell have also been calculated at different applied average current densities (2, 4.1, and 8.2 mA cm−2) through numerical simulation by using finite element based software. The numerical simulation result of the primary current distribution is then compared with the analytical solution and a good match is found. Experimentally, single Cu metal electrodeposition is carried out at different applied average current densities (2, 4.1, and 8.2 mA cm−2) in a modified Hull. The current distribution (primary, secondary, and tertiary) results obtained from the numerical simulation are compared with the experimental results and a satisfactory match is found. Surface morphology of the Cu deposits is examined using scanning electron microscopy (SEM). Srinivas Palli and Suhash R. Dey Copyright © 2016 Srinivas Palli and Suhash R. Dey. All rights reserved. Square Wave Voltammetric Determination of Residues of Carbendazim Using a Fullerene/Multiwalled Carbon Nanotubes/Nafion/Coated Glassy Carbon Electrode Sun, 31 Jan 2016 09:36:06 +0000 A glassy carbon electrode (GCE) was modified with a fullerene/Multiwalled Carbon Nanotubes (MWCNTs)/Nafion composite and applied to the determination of carbendazim, a fungicide. The voltammetric behavior of the analyte was investigated using Cyclic Voltammetry (CV), on the bare GCE and on the same electrode coated by a thin film of the composite material. The electrode response was more than fourfold important on the modified electrode, due to electrical conductivity of fullerene and MWCNT and to favorable electrostatic interaction between the negatively charged Nafion and the protonated fungicide. A sensitive electroanalytical procedure based on Square Wave Voltammetry (SWV) was then developed to detect the analyte. Under the optimum conditions, a linear relationship was obtained between the peak current and the concentration of carbendazim, in the range from 2.0 × 10−8 mol/L to 3.5 × 10−7 mol/L, leading to a detection limit of 1.7 × 10−8 mol/L and to a quantification limit of 5.57 × 10−8 mol/L. The developed procedure was successfully applied to detect carbendazim upon adsorption by some ferritic soils. Djimadoum N. Teadoum, Seraphine K. Noumbo, Kamdem T. Arnaud, Temgoua T. Ranil, Antoine D. Mvondo Zé, and Ignas K. Tonle Copyright © 2016 Djimadoum N. Teadoum et al. All rights reserved. Utility of Activated Glassy Carbon and Pencil Graphite Electrodes for Voltammetric Determination of Nalbuphine Hydrochloride in Pharmaceutical and Biological Fluids Wed, 27 Jan 2016 08:49:50 +0000 This work compares voltammetric response of nalbuphine hydrochloride (NP·HCl) at both activated glassy carbon and pencil graphite electrodes. The electrochemical oxidation of the drug was studied using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) techniques. For analytical purpose a well-resolved irreversible diffusion controlled voltammetric peak was established in Britton-Robinson (B-R) buffer solution of pH 6.00 using pencil graphite electrode (PGE). Using activated glassy carbon electrode (GCE) a well-resolved irreversible diffusion controlled voltammetric peak was obtained at pH 7.00 using the same buffer solution. According to the linear relationship between the peak current and NP·HCl concentration, DPV and SWV methods were developed for their quantitative determination in pharmaceutical and human biological fluids. The linear response was obtained in the range from to  mol L−1 using PGE and from to  mol L−1 using a GC electrode, respectively. Precision and accuracy of the developed method were checked by recovery studies. Hoda M. Elqudaby, Hassan A. M. Hendawy, Eglal R. Souaya, Gehad G. Mohamed, and Ghada M. G. Eldin Copyright © 2016 Hoda M. Elqudaby et al. All rights reserved. A Method for the Simultaneous Cleansing of H2S and SO2 Sun, 17 Jan 2016 14:16:33 +0000 A method for the simultaneous electrochemical purification of hydrogen sulfide and sulfur dioxide from sea water or industrial wastes is proposed. Fundamentally the method is based on the electrochemical affinity of the pair H2S and SO2. The reactions (oxidation of H2S and reduction of SO2) proceed on а proper catalyst in a flow reactor, without an external power by electrochemical means. The partial curves of oxidation of H2S and reduction of SO2 have been studied electrochemically on different catalysts. Following the additive principle the rate of the process has been found by intersection of the curves. The overall process rate has been studied in a flow type reactor. Similar values of the process rate have been found and these prove the electrochemical mechanism of the reactions. As a result the electrochemical method at adequate conditions is developed. The process is able to completely convert the initial reagents (concentrations ), which is difficult given the chemical kinetics. Dzhamal R. Uzun, Elena Razkazova-Velkova, Venko Beschkov, and Konstantin Petrov Copyright © 2016 Dzhamal R. Uzun et al. All rights reserved. Investigation of Imbalanced Activated Carbon Electrode Supercapacitors Wed, 30 Dec 2015 06:29:42 +0000 Imbalanced supercapacitor was constructed by using various ratio of activated carbon (AC) of positive to negative electrode. The electrochemical behavior of imbalanced supercapacitor was investigated using 1.0 M spiro-(1,1′)-bipyrrolidinium tetrafluoroborate electrolyte in propylene carbonate. The results showed that there are some factors that influenced the imbalanced supercapacitor with different AC ratio of positive to negative electrode, the utilization of AC, electrode potential distribution, and life cycle. The imbalanced supercapacitor with an AC weight ratio of 80 : 120 of positive to negative electrode has an average potential distribution in each electrode, and it revealed the best electrochemical performance: specific capacitor was 39.6 Fg−1, while the charge-discharge efficiency was 97.2% after 2000 life cycle tests. Tieshi He, Xue Ren, Junping Nie, Jun Ying, and Kedi Cai Copyright © 2015 Tieshi He et al. All rights reserved. A Novel Electrochemical Method for Protionamide Determination Based on Its Interaction with Alizarin Red S Thu, 20 Aug 2015 13:25:07 +0000 The interaction of protionamide with alizarin red S (ARS) and its analytical application were carefully investigated in this contribution. The interaction conditions were carefully studied and optimized by cyclic voltammetry. Under the optimum conditions, the cyclic voltammetry curve of ARS showed an oxidation peak with the peak potential of 0.57 V. After the addition of protionamide to the ARS solution, the peak potential was negatively moved, and meanwhile the oxidation peak current decreased apparently to the concentration of protionamide and then a new method for the protionamide determination was established. The linear equation between the decreasing current (Δip) and protionamide concentration was got as Δip (μA) = 0.01514 (mg/L) −0.01553   with the linear range of 10.0~50.0 mg/L, and the detection limit () was got as 8.25 μg/mL. The effects of coexisting substances on the determination were carefully investigated and the protionamide artificial and tablet samples were detected with satisfactory results. Weili Zhang, Xueliang Niu, Hua Zhang, Qingqing Jiang, and Pingping Zhang Copyright © 2015 Weili Zhang et al. All rights reserved. Evaluation of Hydrophilized Graphite Felt for Electrochemical Heavy Metals Detection (Pb2+, Hg2+) Wed, 08 Jul 2015 10:34:14 +0000 Hydrophilized graphite felt has been used, for the first time, for the electrochemical detection of Hg2+ ions both as single metal species and via its simultaneous detection with Pb2+. To do so, square wave voltammetry (SWV) method was developed with alginate modified graphite felt as working electrode. The structure of the graphite felt such as its high porosity and specific surface area coupled with its good electrical conductivity allows achieving large peak currents via the SWV method, suggesting that the alginate coating helps to preconcentrate metals at the carbon surface. The as-described electrode has low cost, it is easy to manipulate, and the electrochemical analysis can be performed by simple immersion of the felt in the metal solution. Laila Bouabdalaoui, Benjamin Le Ouay, Thibaud Coradin, and Christel Laberty-Robert Copyright © 2015 Laila Bouabdalaoui et al. All rights reserved. An Empirical Rate Constant Based Model to Study Capacity Fading in Lithium Ion Batteries Tue, 07 Jul 2015 12:01:13 +0000 A one-dimensional model based on solvent diffusion and kinetics to study the formation of the SEI (solid electrolyte interphase) layer and its impact on the capacity of a lithium ion battery is developed. The model uses the earlier work on silicon oxidation but studies the kinetic limitations of the SEI growth process. The rate constant of the SEI formation reaction at the anode is seen to play a major role in film formation. The kinetics of the reactions for capacity fading for various battery systems are studied and the rate constants are evaluated. The model is used to fit the capacity fade in different battery systems. Srivatsan Ramesh, K. Venkata Ratnam, and Balaji Krishnamurthy Copyright © 2015 Srivatsan Ramesh et al. All rights reserved. Modeling the Lithium Ion/Electrode Battery Interface Using Fick’s Second Law of Diffusion, the Laplace Transform, Charge Transfer Functions, and a [4, 4] Padé Approximant Wed, 17 Jun 2015 13:39:02 +0000 This work investigates a one-dimensional model for the solid-state diffusion in a LiC6/LiMnO2 rechargeable cell. This cell is used in hybrid electric vehicles. In this environment the cell experiences low frequency electrical pulses that degrade the electrodes. The model’s starting point is Fick’s second law of diffusion. The Laplace transform is used to move from time as the independent variable to frequency as the independent variable. To better understand the effect of frequency changes on the cell, a transfer function is constructed. The transfer function is a transcendental function so a Padé approximant is found to better describe the model at the origin. Consider . John H. Summerfield and Charles N. Curtis Copyright © 2015 John H. Summerfield and Charles N. Curtis. All rights reserved. Structural and Electrochemical Analysis of PMMA Based Gel Electrolyte Membranes Sun, 18 Jan 2015 07:40:59 +0000 New gel polymer electrolytes containing poly(vinylidene chloride-co-acrylonitrile) and poly(methyl methacrylate) are prepared by solution casting method. With the addition of 60 wt.% of EC to PVdC-AN/PMMA blend, ionic conductivity value  S cm−1 has been achieved. XRD and FT-IR studies have been conducted to investigate the structure and complexation in the polymer gel electrolytes. The FT-IR spectra show that the functional groups C=O and C≡N play major role in ion conduction. Thermal stability of the prepared membranes is found to be about 180°C. Chithra M. Mathew, K. Kesavan, and S. Rajendran Copyright © 2015 Chithra M. Mathew et al. All rights reserved. Electrocatalytic Oxidation and Determination of Cysteine at Oxovanadium(IV) Salen Coated Electrodes Sun, 28 Dec 2014 07:40:33 +0000 A transition metal complex, oxovanadium(IV) salen (where salen represents N,N′-bis(salicylidene)ethylenediamine) is immobilized on glassy carbon (GC) electrodes and utilized for electrocatalytic oxidation of cysteine. In presence of oxovanadium(IV) salen, increased oxidation current is observed due to the effective oxidation of cysteine by the electrogenerated oxovanadium(V) salen species. The oxidation current linearly varies with the concentration of cysteine from 0.1 to 1.0 mM. The modified electrode has good sensitivity and low limit of detection. These properties make the oxovanadium(IV) salen as an effective electrocatalyst for the determination of cysteine. Piyush Kumar Sonkar, Vellaichamy Ganesan, and Vijay Rao Copyright © 2014 Piyush Kumar Sonkar et al. All rights reserved. Selection of the Best Process Stream to Remove Ca2+ Ion Using Electrodialysis from Sugar Solution Sun, 14 Dec 2014 10:37:09 +0000 Electrodialytic removal of calcium chloride (CaCl2, 25–50 mol·m−3) from 5% sugar solution was executed in batch recirculation mode. Calcium ion removal rate was monitored with (i) applied potential, (ii) feed flow rate, (iii) solution viscosity and conductivity, and (iv) catholyte streams (NaOH or sodium salt of ethylene diamine tetraacetic acid-acetic acid, Na2EDTA-AA). Unsteady state model for ion concentration change was written for the ED cell used. Linearized Nernst-Planck equation instead of Ohm’s law was applied to closely obtain the current density and concentration change theoretically. The model developed could closely predict the experimental observation. Mass transfer coefficients and specific energy densities were estimated for each combination of catholyte stream used. NaOH showed better performance for a short duration over Na2EDTA-acetic acid combination. Jogi Ganesh Dattatreya Tadimeti, Shilpi Jain, Sujay Chattopadhyay, and Prashant Kumar Bhattacharya Copyright © 2014 Jogi Ganesh Dattatreya Tadimeti et al. All rights reserved. Solvent Effects on the Electrochemical Behavior of TAPD-Based Redox-Responsive Probes for Cadmium(II) Tue, 25 Nov 2014 11:12:20 +0000 Two tetralkylated phenylenediamines (TAPD) 1 and 2 have been prepared by reductive alkylation of para-dimethylaminoaniline with furfural or thiophene 2-carboxaldehyde, respectively. Their chelation ability has been evaluated as electrochemical guest-responsive chemosensors for Cd(II) in acetonitrile (ACN), dimethylformamide (DMF), propylene carbonate (PC), and nitromethane (NM). The voltamperometric studies showed that these compounds are able to bind the Cd(II) cation with strong affinities except in DMF. The redox features of the chemosensors changed drastically when they are bounded to Cd(II) to undergo important anodic potential peak shifts comprised between ca. 500 and ca. 900 mV depending on the solvent. The addition of ∼4–10% molar triflic acid (TfOH) was found to be necessary to achieve rapidly the cation chelation which is slow without the acid. The electrochemical investigations suggested the formation of 1 : 2 stoichiometry complexes [Cd(L)2]2+. The results are discussed in terms of solvent effects as a competitive electron donating ligand to the cation. The reaction coupling efficiency (RCE) values were determined and were also found to be solvent-dependent. Rihab Sahli, Janet Bahri, Issa Tapsoba, Khaled Boujlel, and Noureddine Raouafi Copyright © 2014 Rihab Sahli et al. All rights reserved. Action of Chicory Fructooligosaccharides on Biomimetic Membranes Sun, 16 Nov 2014 11:48:27 +0000 Fructooligosaccharides from chicory (FOSC) are functional prebiotic foods recognized to exert several well-being effects in human health and animal production, as decreasing blood lipids, modulating the gut immune system, enhancing mineral bioavailability, and inhibiting microbial growth, among others. Mechanisms of actions directly on cell metabolism and structure are however little known. In this sense this work was targeted to investigate the interaction of FOSC with biomimetic membranes (liposomes and supported bilayer membrane; s-BLM) through cyclic voltammetry, impedance spectroscopy, spectrofluorimetry, and microscopy. FOSC was able to disrupt the membrane structure of liposomes and s-BLM from the onset of molecular pores induced on it. The mechanism of interaction of fructans with biomimetic membranes suggests hydrogen bonding between the polyhydroxylated structure of the oligosaccharides and the negative polar group of L--phosphatidylcholine (PC) present in both liposomes and s-BLM. A. F. Barbosa, R. S. Henrique, A. S. Lucho, V. Paffaro Jr., and J. M. Schneedorf Copyright © 2014 A. F. Barbosa et al. All rights reserved. Effect of Low Cobalt Loading on TiO2 Nanotube Arrays for Water-Splitting Sun, 09 Nov 2014 07:23:41 +0000 This work is intended to define a new possible methodology for the TiO2 doping through the use of an electrochemical deposition of cobalt directly on the titanium nanotubes obtained by a previous galvanostatic anodization treatment in an ethylene glycol solution. This method does not seem to cause any influence on the nanotube structure, showing final products with news and interesting features with respect to the unmodified sample. Together with an unmodified photoconversion efficiency under UV light, the cobalt doped specimen reports an increase of the electrocatalytic efficiency for the oxygen evolution reaction (OER). Alfonso Pozio Copyright © 2014 Alfonso Pozio. All rights reserved. Synthesis and Characterization of Electrodeposited C-PANI-Pd-Ni Composite Electrocatalyst for Methanol Oxidation Thu, 16 Oct 2014 14:42:07 +0000 Electropolymerization of aniline at the graphite electrodes was achieved by potentiodynamic method. Electrodeposition of Pd (C-PANI-Pd) and Ni (C-PANI-Ni) and codeposition of Pd-Ni (C-PANI-Pd-Ni) microparticles into the polyaniline (PANI) film coated graphite (C-PANI) were carried out under galvanostatic control. The morphology and composition of the composite electrodes were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods in acidic medium. The C-PANI-Pd-Ni electrode showed an improved catalytic performance towards methanol oxidation in terms of lower onset potential, higher anodic oxidation current, greater stability, lower activation energy, and lower charge transfer resistance. The enhanced electrocatalytic activity might be due to the greater permeability of C-PANI films for methanol molecules, better dispersion of Pd-Ni microparticles into the polymer matrixes, and the synergistic effects between the dispersed metal particles and their matrixes. S. S. Mahapatra, S. Shekhar, B. K. Thakur, and H. Priyadarshi Copyright © 2014 S. S. Mahapatra et al. All rights reserved. Role of Indium Alloying with Lead as a Means to Reduce the Passivation Phenomena in Lead/Acid Batteries Tue, 23 Sep 2014 00:00:00 +0000 The influence of indium content on the anodic behaviour of Pb-In alloys in 4 M H2SO4 solution is investigated by potentiodynamic, potentiostatic, chronopotentiometric, and cyclic voltammetric techniques. The composition and microstructure of the corrosion layer on Pb-In alloys are characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDX), and scanning electron microscopy (SEM). The potentiodynamic and chronopotentiometric curves show that the anodic behavior of all investigated electrodes exhibits active/passive transition. The active dissolution (except for alloy I) and passive currents increase with increasing both In content and temperature. This indicates that the conductivity of the anodic film on Pb-In alloy is enhanced. This study exhibits that indium catalyses the oxidation of Pb (II) to Pb (IV) and facilitates the formation of a more highly conductive corrosion layer on lead. Alloy I (0.5% In) exhibits that the corrosion rate is lower, while the passive current is higher than that of Pb. XRD, EDX, and SEM results reveal that the formation of both PbSO4 and PbO on the surface decreases gradually with increasing In level in the alloy and completely disappear at higher In content (15% In). Therefore, recharge of the battery will be improved due to indium addition to Pb. Abdel-Rahman El-Sayed, Hossnia S. Mohran, and Hoda Abdel Shafy Shilkamy Copyright © 2014 Abdel-Rahman El-Sayed et al. All rights reserved. Using Poly-L-Histidine Modified Glassy Carbon Electrode to Trace Hydroquinone in the Sewage Water Mon, 08 Sep 2014 00:00:00 +0000 A sensitive voltammetric method for trace measurements of hydroquinone in the sewage water is described. The poly-L-histidine is prepared to modify the glassy carbon electrode in order to improve the electrochemical catalysis of interesting substances such as hydroquinone. The influence of the base solution, pH value, and scanning speed on the tracing of hydroquinone is discussed, and the experimental procedures and conditions are optimized. The laboratory results show that it is possible to construct a linear calibration curve between the peak current of hydroquinone on modified electrode and its concentration at the level of 0.00001 mol/L. The potential limitation of the method is suggested by a linear peaking shift model as well. The method was successfully applied to the determination of hydroquinone in the actual sample of industrial waste water. Bin Wang and Jun Steed Huang Copyright © 2014 Bin Wang and Jun Steed Huang. All rights reserved. Electron Transfer of Myoglobin Immobilized in Au Electrodes Modified with a RAFT PMMA-Block-PDMAEMA Polymer Sun, 31 Aug 2014 08:24:50 +0000 Myoglobin was immobilized with poly(methyl methacrylate)-block-poly[(2-dimethylamino)ethyl methacrylate]PMMA-block-PDMAEMA polymer synthesized by reversible addition-fragmentation chain transfer technique (RAFT). Cyclic voltammograms gave direct and slow quasireversible heterogeneous electron transfer kinetics between Mb-PMMA-block-PDMAEMA modified electrode and the redox center of the protein. The values for electron rate constant () and transfer coefficient () were ·s−1 and , respectively. The reduction potential determined as a function of temperature (293–328 K) revealed a value of reaction center entropy of of  J·mol−1·K−1 and enthalpy change of  kJ·mol−1, suggesting solvent effects and charge ionization atmosphere involved in the reaction parallel to hydrophobic interactions with the copolymer. The immobilized protein also exhibits an electrocatalytical response to reduction of hydrogen peroxide, with an apparent Km of  μM. The overall results substantiate the design and use of RAFT polymers towards the development of third-generation biosensors. Carla N. Toledo, Fábio H. Florenzano, and José M. Schneedorf Copyright © 2014 Carla N. Toledo et al. All rights reserved. Exploration of Electrochemical Intermediates of the Anticancer Drug Doxorubicin Hydrochloride Using Cyclic Voltammetry and Simulation Studies with an Evaluation for Its Interaction with DNA Sun, 03 Aug 2014 11:46:06 +0000 Electrochemical behavior of the anticancer drug doxorubicin hydrochloride was studied using cyclic voltammetry in aqueous medium using Hepes buffer (pH~7.4). At this pH, doxorubicin hydrochloride undergoes a reversible two-electron reduction with value − mV (versus Ag/AgCl, saturated KCl). Depending on scan rates, processes were either quasireversible (at low scan rates) or near perfect reversible (at high scan rates). This difference in behavior of doxorubicin hydrochloride with scan rate studied over the same potential range speaks of differences in electron transfer processes in doxorubicin hydrochloride. Attempt was made to identify and understand the species involved using simulation. The information obtained was used to study the interaction of doxorubicin hydrochloride with calf thymus DNA. Cathodic peak current gradually decreased as more calf thymus DNA was added. The decrease in cathodic peak current was used to estimate the interaction of the drug with calf thymus DNA. Nonlinear curve fit analysis was applied to evaluate the intrinsic binding constant and site size of interaction that was compared with previous results on doxorubicin hydrochloride-DNA interaction monitored by cyclic voltammetry or spectroscopic techniques. Partha Sarathi Guin and Saurabh Das Copyright © 2014 Partha Sarathi Guin and Saurabh Das. All rights reserved. Synthesis and Electrochemical Performance of LiMnPO4 by Hydrothermal Method Tue, 08 Jul 2014 07:19:54 +0000 LiMnPO4 with olivinestructure which is the promising candidate for high voltage cathode material was synthesized by hydrothermal method. In order to synthesize high purity and well-defined LiMnPO4, several precursors for Li, Mn, and P sources and hydrothermal reaction parameters including temperature and [H2O]/[Mn] value are optimized. By analyzing the structure, Mn valence, morphology, and chemical ratio via XRD, XPS, Raman, SEM, and ICP LiMnPO4 synthesized from manganese acetate tetrahydrate have single phase of LiMnPO4 without impurity and showed charge and discharge reaction caused by Mn2+/Mn3+ redox. Specific capacity of synthesized LiMnPO4 grew up during cycling. Moreover, when hydrothermal temperature was set at 150°C and [H2O]/[Mn] value was set at 15, discharge capacity as high as 70 mAh/g was obtained at rate. Daichi Fujimoto, Yu Lei, Zheng-Hong Huang, Feiyu Kang, and Junichi Kawamura Copyright © 2014 Daichi Fujimoto et al. All rights reserved. Synthesis of Nitrogen Doped Carbon and Its Enhanced Electrochemical Activity towards Ascorbic Acid Electrooxidation Thu, 26 Jun 2014 13:31:17 +0000 Nitrogen doped carbon, synthesized by a novel way of carbonizing polyaniline in an inert atmosphere at a constant temperature of , exhibits several unique features. The carbon: nitrogen ratio is found to increase with the treatment duration up to 120 minutes and a mass reduction of 60 wt% is observed with an interesting observation of the retention of the bulk polymer morphology, surprisingly, even after the carbonization process. The electrochemical activity evaluated with potassium hexacyanoferrate and hexamine ruthenium redox systems at a regular time interval helps to tune the catalytic activity. This type of nitrogen doped carbon prepared from polyaniline base exhibits excellent electrocatalytic activity as illustrated by the oxidation of ascorbic acid in neutral medium. Sankararao Mutyala and Mathiyarasu Jayaraman Copyright © 2014 Sankararao Mutyala and Mathiyarasu Jayaraman. All rights reserved. Pd-Au Electrocatalysts for Hydrogen Evolution Reaction at Neutral pH Mon, 31 Mar 2014 12:12:23 +0000 Pd-Au codeposits with different ratio of both metals were electrodeposited on carbon felt, characterized by scanning electron microscopy, and investigated as electrocatalysts towards hydrogen evolution reaction in neutral phosphate buffer solution. The quantities of the produced hydrogen gas with different electrocatalysts, estimated from data obtained by chronoamperometry, were confirmed by mass spectrometry analysis. The highest hydrogen evolution rate was achieved with the electrocatalysts, produced from electrolyte with equal Pd and Au content. Elitsa Chorbadzhiyska, Mario Mitov, Georgi Hristov, Nina Dimcheva, Lori Nalbandian, Antigoni Evdou, and Yolina Hubenova Copyright © 2014 Elitsa Chorbadzhiyska et al. All rights reserved.