Sharif Digital Repository

ZnFe2O4 nanoparticles have been successfully prepared through a controlled microwave-assisted co-precipitation. X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used for the structural, morphological and magnetic investigation of the product. SEM micrographs of ZnFe2O4 nanopowder also reveal that nanoparticles have spherical shape. Average particle size was obtained as 12 nm from XRD. Catalytic activity of ZnFe2O4 nanopowder for O-acylation of alcohol and phenol has been investigated. A trace amount of ZnFe2O4 has been effectively used as a nanocatalyst for the acylation of alcohol and... 

An indirect colorimetric method is presented for detection of trace amounts of hydroquinone (1), catechol (2) and pyrogallol (3). The reduction of AuCl4- to Gold nanoparticles (Au-NPs) by these phenolic compounds in the presence of cetyltrimethylammonium chloride (CTAC) produced very intense surface plasmon resonance peak of Au-NPs. The plasmon absorbance of Au-NPs allows the quantitative colorimetric detection of the phenolic compounds. The calibration curves derived from the changes in absorbance at λ = 568 nm were linear with concentration of hydroquinone, catechol and pyrogallol in the range of 7.0 × 10-7 to 1.0 × 10-4M, 6.0 × 10-6 to 2.0 × 10-4 M and 6.0 × 10-7 to 1.0 × 10-4 M,... 

A promising electrochemical sensor was developed based on a layer by layer process by electro-polymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the multi-walled carbon nanotubes (MWCNTs) pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The electrochemical behavior of SUM was investigated on the surface of the modified electrode using linear sweep voltammetry (LSV). The results showed a remarkable increase (∼12 times) in the anodic peak current of SUM in comparison to the bare GCE. The effect of experimental variables such... 

Multi-walled carbon nanotubes decorated with Fe 3O 4 nanoparticles (Fe 3O 4NPs/MWCNT) were prepared and used to construct a novel biosensor for the simultaneous detection of adenine and guanine. The direct electro-oxidation of adenine and guanine on the modified electrode were investigated by linear sweep voltammetry. The results indicate a remarkable increase in the oxidation peak currents together with negative shift in the oxidation peak potentials for both adenine and guanine, in comparison to the bare glassy carbon electrode (GCE). The surface morphology and nature of the composite film deposited on GCE were characterized by transmission electron microscopy, atomic force microscopy,... 

A composite film constructed of surfactant doped over-oxidized polypyrrole and multi-walled carbon nanotube was prepared on the surface of glassy carbon electrode by the electro-polymerization method. Surface characterization of the modified electrode was performed by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectrometry. The investigations have been proved that the over-oxidation of the modifier film resulted in a porous thin layer that improves the interlayer diffusion mechanism for the electroactive species. On the other hand, the negative charge density on the surface of the electrode excludes the negative analytes (e.g. ascorbate and Fe(CN)63?/4?)... 

A modified glassy carbon electrode, prepared by potentiostatic electrodeposition of platinum-ruthenium nanoparticles (Pt-RuNPs) onto a multi-walled carbon nanotube (MWCNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric responses toward methyldopa (m-dopa) compared to glassy carbon electrodes individually coated with MWCNT or Pt-RuNPs. The surface morphology and nature of the hybrid film (Pt-RuNPs/MWCNT) deposited on glassy carbon electrodes was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. A remarkable enhancement in the microscopic area of the electrode together... 

The preparation and electrochemical performance of the carbon nanotube-paste electrode modified with salophen complexes of cobalt(III) perchlorate, with various substituents on the salophen ligand, as well as their electrocatalytic activity toward the oxidation of N-acetylcysteine (NAC) is investigated. Several Schiff base complexes containing various nucleophilic and electrophilic functional groups were prepared, and their electrochemical characteristics for the electro-oxidation of NAC were evaluated using cyclic and differential pulse voltammetry (CV and DPV). The results revealed, the modified electrodes show an efficient and selective electrocatalytic activity toward the anodic... 

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...