Analytical & Bioanalytical Electrochemistry
Volume:11 Issue: 1, Jan 2019

In this study a novel electrode was developed to simultaneous determination of serotonin (5-HT) and sertraline (ST) in the presence of uric acid based on a glassy carbon electrode modified by a composition of Fe3O4@MCM-48-SO3H and multi-wall carbon nanotubes (MWCNTs) (Fe3O4@MCM-48-SO3H/MWCNTs/GCE). The results showed that the modified electrode is a promising one for the simultaneous determination of 5-HT and ST in the presence of uric acid (UA) at optimized circumstances. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to study behavior of the modified electrode. The DPV results showed a linear relationship between 5-HT concentration and the oxidation peak current in the concentration ranges from 0.05 μM to 100 μM with a detection limit of 0.015 μM. For ST, a linear relationship between the concentration and the oxidation peak current in the ranges from 0.1 μM to 85 μM was obtained. The corresponding detection limit for ST was 0.025 μM. The Fe3O4@MCM-48-SO3H/MWCNTs/GCE was used for determination of 5-HT and ST in real samples like human blood serum and urine with reasonable outcomes.

The corrosion inhibition of carbon steel in acidic medium (1 M HCl) containing a borated vitreous glasses was studied by electrochemical technique (potentiodynamic polarization and electrochemical impedance spectroscopy).The various vitreous samples were synthesized from ammonium dihydrogen phosphate (NH4) 2HPO4), the niobium oxide Nb2O5, the Bi2O3 bismuth oxide, the B2O3 boron oxide and the niobium oxide Nb2O5. The vitreous compositions are correlated with the system Bi2O3-B2O3- (0.5Nb2O5 -0.5P2O5) by stoichiometric mixing. These phases were characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR). Polarization curve technique reveals that the inhibition efficiency E% increased with the concentration of the different borated vitreous which appears to be a anodic type inhibitors in the acidic medium. Electrochemical impedance spectroscopy confirms this result, indeed the transfer resistance increases with these compounds concentration. The action mechanism of vitreous phases has been elucidated by a thermodynamic study.

In this research, plasma electrolytic oxidation (PEO) coating on AZ31B magnesium alloy having various concentrations has been studied in order to amend the surface corrosion resistance. To do this, phosphate electrolyte with different concentrations of 4, 8 and 10 g/l is investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization tests on an uncoated base alloy and a coated one are studied in a body simulant physiological solution (Ringer's solution). Surface morphology and microstructural surveys were done by X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM). The obtained results of this study displayed that rising the sodium phosphate concentration led to an increase in coating thickness and decreases its porosity. The highest corrosion resistance arose from the lowest corrosion current density (0.45×10-6 A/cm2) of the formed coating in electrolyte containing 10 g/l sodium phosphate.

The inhibition effect of three acetanilide compounds namely acetanilide (Ac1), o-methyl acetanilide (Ac2) and p-nitroacetanilide (Ac3) on the corrosion of 304L in 1 M HCl solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy methods. The results show that compound Ac3 is the best inhibitor and the inhibition efficiency follows the order: Ac3>Ac2>Ac1. Potentiodynamic polarization curves indicated that the inhibitors acted as mixed-type inhibitors. The adsorption of inhibitors on the stainless steel surface obeys to the Langmuir adsorption isotherm and has physisorption mechanism. All techniques employed in this study show the same order of inhibition efficiency.

In this work, we synthesized nano plate oxalate precursor via solvothermal method to obtain Nano Sponge Li1.2Mn0.54Ni0.13Co0.13O2 (NS-LMNCO) cathode material. During solvothemal process, ethanol and water solvents arrange oxalate nuclei to form plate-like shape. With increasing temperature at calcination step, the oxalate precursor is converted to NS-LMNCO by removing CO2. The structure, morphology and elemental composition of synthesized samples are investigated with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron spectroscopy (XPS), respectively. The thickness and length of nano plate are 60 nm and 2 μm, respectively. However, the diameter of particles made NS-LMNCO is 40 nm. The NS-LMNCO delivers discharge capacities of 207.6 mAh g-1 at 0.1 C. Furthermore, electrochemical data show that NS-LMNCO sample retain discharge capacities of 147.5 mAh g-1 (71.1% of the first discharge capacity) after 50 cycles at 0.1 C-rate. The results obtained in this work clearly confirmed that electrochemical properties of lithium ion cell e.g. specific capacity, cycle life and rate performance can be significantly controlled by properties of active materials, especially cathode particles, e.g. porosity, surface area and density related to morphology of active particles.

Development of a facile synthesis rout for preparation of polymer coted, metal ion doped magnetic nanoparticles, which have proper magnetic and physicochemical properties for bio-medical uses, is one of the most active research areas in advanced magnetic nano-materials. In this work, we demonstrate an easy electrochemical method for fabrication of PEG-coated Zn2+ or Gd3+ doped magnetic iron oxides (i.e. PEG/Zn-MIOs and PEG/Gd-MIOs). Characterization of the synthesized MIOs was carried out by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR), Field-emission electron microscopy (FE-SEM), thermal gravimetric analysis (TGA), and vibrating sample magnetometry (VSM) analyses. The XRD and EDAX analyses proved that the electro-synthesized MIOs were magnetite (Fe3O4) doped with 8.6% Zn2+ and/or 19.7% Gd3+. The PEG layer on the Zn-MIOs and/or Gd-MIOs surface was evidenced by FT-IR. FE-SEM showed a spherical morphology with average diameters of 20 nm and 25 nm for PEG/Zn-MIOs and PEG/Gd-MIOs, respectively. TGA data demonstrated that the PEG content of Gd-MIOs was about 10% by weight. Superparamagnetic nature of both prepared magnetic powders was verified by VSM measurements. In final, the analyses results supported that the prepared magnetic nano-particles have suitable size, crystal phase, surface layer and magnetism for bio-medical uses.

In this work, chemical precipitation was used to form ytterbium tungstate nanoparticles (Yb2(WO4)3). This was achieved through the direct addition of a solution of ytterbium ions in water to that of tungstate. The structural and chemical properties of the prepared nanomaterial were evaluated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (XRD). The modified electrochemical electrode was prepared using synthesized ytterbium tungstate nanoparticles and electrochemical behavior of this electrode was investigated by electrochemical methods like CV, CA and DPV. Also, the effects concentration, pH and the potential scan rate were on the electrochemical process were investigated. It was found that the electrode modified with ytterbium tungstate nanoparticles enjoys excellent electrocatalytic activity for nitrotriazolone (NTO). The response of the electrode to NTO was linear in the concentration range of 10-3 M to 10-5 M, and the limit of detection in DPV analyses reached 5×10-6 M. Good performance for determination of NTO in water samples was obtained by DPV method.

In this paper, magnetic iron oxide nanoparticles (MIOs) of controlled size distribution were electrochemically fabricated through applying typical galvanostatic deposition conditions from dissolved iron(II) chloride, iron(III) nitrate, Gd(III) chloride salts in aqueous media. The produced deposit was MIOs doped with ~19% Gd3+ cations (i.e. Gd-MIOs). In situ surface grafting of the deposited Gd-MIOs with polyvinylpyrrolidone (PVP/Gd-MIOs) polymer was also achieved through only addition of PVP into the deposition bath without using any supporting electrolyte. The presence of PVP-grafted layer onto the Gd-MIOs surface was supported via EDS and FTIR data. The magnetic evolution results indicated that the prepared PVP/Gd-MIOs powder has all the magnetic qualification requirements and hence could be a potential candidate for use in bio-medicine.

In this paper, an electrochemical method was developed for fabrication of copper ions doped iron oxide particles and their surface coating with a bio-compatible layer. Using this method, polyethylenimine-coated Cu2+ doped super-paramagnetic magnetite nanoparticles were prepared on the cathode surface through base electro-generation strategy. The prepared PEI/Cu-IOs powder was analyzed by XRD, FE-SEM, EDS and VSM technique. The crystalline magnetite phase of the prepared PEI/Cu-IOs powder was verified by XRD data. FE-SEM observations and EDS data reveled the particle morphology and presence of Cu2+ ions content in the prepared sample, respectively. The FT-IR analysis proved the PEI layer on the surface of the fabricated Cu-IOs nanoparticles. The super-paramagnetic performance of the prepared powder was concluded through the measured negligible remanence (i.e. Mr=0.36 emu/g) and low intrinsic coercivity (i.e. Hci=8.54G). These results certificated the eligibility of prepared nanoparticles for various biomedical applications.

CuAl2O4/CuO nanocomposite were synthesized through the simple and fast procedure (sol-gel method) in the presence of sodium tetraphenylborate NaB(C6H5)4 as the novel capping agent. The analysis of CuAl2O4/CuO nanocomposite was performed through some techniques including, Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray microanalysis (EDX), and Transmission electron microscopy (TEM). Synthesis of nanocomposite used for sensitive electrochemical detection of dopamine (DA). The linear range of 0.5-1 μM and 1-20 μM with the detection limit of 0.08 μM for DA, was obtained using differential pulse voltammetry (DPV) (pH=7.0).