Sharif Digital Repository

Platinum nanowires (PtNWs) were electrodeposited on the polycarbonate templates (PCTs) in aqueous solution of H2PtCl6 in triply distilled water. Nanowires with diameters of 50 and 100 nanometers were electrodeposited on the same condition. The kinetics of electrodeposition process was studied by electrochemical techniques such as voltammetry and chronoamperometry methods. Increasing the scan rate, the peaks shifted to more negative potentials and the current density also increased in each peak which was typical for a diffusion-control process. The potential range for the deposition of platinum nanowires was specified and consequently the potentiostatic i-t transients were utilized to produce... 

Oxygen reduction on a polycrystalline silver electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The reaction occurred by a two-electron pathway. The steps in the mechanism were observed in the cyclic voltammograms recorded with different scan rates. The intermediates formed in the steps were detected by electrochemical impedance spectroscopy  

This article reports experimental results on laser sintering of A356 aluminum alloy and A356/SiC composite powders. Effects of scan rate, sintering atmosphere, hatch spacing, and SiC volume fraction (up to 20%), and particle size (7 and 17 μm) on the densification were studied. The phase formation and microstructural development were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Laser sintering under argon atmosphere exhibited higher densification compared to nitrogen. A faster sintering kinetics was observed as the scan rate decreased. Except at a low SiC content (5 vol%), the composite powders exhibited... 

By combination of 1-ethyl-3-methyl immidazolium ethyl sulfate as a typical room temperature ionic liquid (IL) and graphene oxide (GO) nanosheets, a nanocomposite was introduced for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase (GOx). The enzyme on the IL-GO-modified glassy carbon electrode exhibited a quasireversible cyclic voltammogram corresponding to the flavine adenine dinucleotide/FADH2 redox prosthetic group of GOx. At the scan rate of 100 mV s-1, the enzyme showed a peak-to-peak potential separation of 82 mV and the formal potential of -463 mV (vs Ag/AgCl in 0.1 M phosphate buffer solution, pH 7.0). The kinetic parameters of the charge transfer... 

Ni II-(N,N′-bis(2,4-dihydroxyacetophenone)-2, 2-dimethylpropandiimine (Ni II{salnptn(4-OH) 2}) complex has been encapsulated within the supercage of zeolite-NaY by reacting Ni 2+-exchanged NaY with the flexible Schiff-base ligand that diffuses into the cavities. The encapsulated complex is characterized by EDX, scanning electron microscopy, powder X-ray diffraction, FT-IR, and cyclic voltammetry studies. Density functional calculation is being carried out on both the free nickel Schiff-base complex and that encapsulated in NaY zeolite to investigate changes in structural parameters, energies of the HOMO and LUMO, and absolute hardness and softness. Electrochemical properties of the NaY... 

Nickel and nickel-manganese alloy modified graphite electrodes (G/Ni and G/NiMn) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, in the presence of methanol NiMn alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel hydroxide increase is followed by a decrease in the corresponding cathodic current in presence of methanol. The anodic peak currents show linear dependency upon the... 

Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox processes and electro-catalytic activities towards the oxidation of glucose in alkaline solutions. The methods of cyclic voltammetry (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. It is also observed that the overpotential for O 2 evolution increases for NiCu alloy modified electrode. In CV studies, NiCu alloy modified electrode yields significantly higher... 

In the present work, an amperometric inhibition biosensor for the determination of sulfide has been fabricated by immobilizing Coprinus cinereus peroxidase (CIP) on the surface of screen printed electrode (SPE). Chitosan/acrylamide was applied for immobilization of peroxidase on the working electrode. The amperometric measurement was performed at an applied potential of -150. mV versus Ag/AgCl with a scan rate of 100. mV in the presence of hydroquinone as electron mediator and 0.1. M phosphate buffer solution of pH 6.5. The variables influencing the performance of sensor including the amount of substrate, mediator concentration and electrolyte pH were optimized. The determination of sulfide... 

A sensitive and selective electrochemical sensor was fabricated via the drop-casting of carbon nanoparticles (CNPs) suspension onto a glassy carbon electrode (GCE). The application of this sensor was investigated in simultaneous determination of acetaminophen (ACE) and tramadol (TRA) drugs in pharmaceutical dosage form and ACE determination in human plasma. In order to study the electrochemical behaviors of the drugs, cyclic and differential pulse voltammetric studies of ACE and TRA were carried out at the surfaces of the modified GCE (MGCE) and the bare GCE. The dependence of peak currents and potentials on pH, concentration and the potential scan rate were investigated for these compounds... 

A new sensitive and selective electrochemical sensor was developed for determination of naltrexone (NAL) in pharmaceutical dosage form and human plasma. Naltrexone is an opioid antagonist which is commonly used for the treatment of narcotic addiction and alcohol dependence. A voltammetric study of naltrexone has been carried out at the surface of glassy carbon electrode (GCE) modified with Nafion-doped carbon nanoparticles (CNPs). The electrochemical oxidation of naltrexone was investigated by cyclic and differential pulse voltammetric techniques. The dependence of peak currents and potentials on pH, concentration and the potential scan rate was investigated. The electrode characterization... 

We have investigated hydrogen sensing properties of electrodeposited Pd clusters on macroporous silicon substrates. Porous layer was prepared by electrochemical etching of p-type silicon (100) wafer in organic electrolyte DMF (dimethylformamide) diluted by HF (%95 Vol. %). The deposition of Pd was carried out by linear voltammetry (LV) technique. This technique was taken for reduction of palladium ions in the potential range from 0.4 V to -1 V vs. SCE, at the scan rate of 20 mV s-1. Some samples were annealed at 300°C for an hour in air to study the effect of heat treatment on their gas sensitivity. Surface structural and chemical properties of the samples were characterised using Scanning... 

Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. In CV studies, in the presence of methanol NiCu alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel... 

Multi-walled carbon nanotube decorated with silver nanoparticles (AgNPs-MWCNT) is used as an effective strategy for modification of the surface of pyrolytic graphite electrode (PGE). This modification procedure improved colloidal dispersion of the decorated MWCNTs in water, affording uniform and stable thin films for altering the surface properties of the working electrode. Robust electrode for sensing applications is obtained in a simple solvent evaporation process. The electrochemical behavior of sumatriptan (Sum) at the bare PGE and AgNPs-MWCNT modified PGE is investigated. The results indicate that the AgNPs-MWCNT modified PGE significantly enhanced the oxidation peak current of Sum. A...