bakhsh raoof

Copper nanoparticles were fabricated by electro-reduction of CuSO4solution in the presence of cetyltrimethylammonium bromide (CTAB) cationic surfactant as an additive through potentiostatic method. The prepared copper nanoparticles were characterized by scanning electron microscopy (SEM) and electrochemical methods. The SEM images reveal that the nanoparticles with diameters at about 70 nm were uniformly dispersed on the electrode surface. Copper oxide nanoparticles modified glassy carbon electrode (nano CuO/MGCE) was prepared by using consecutive potential cycling between -1.0 to 1.0V at 100mVs −1 in 0.1 M NaOH solution. The electrochemical techniques such ascyclic voltammetry and chronoamperometry showed that the nano CuO/MGCE can catalyze the methanol oxidation in 0.1 M NaOH solution. It has been found that in the course of an anodic potential sweep, the methanol oxidation follows the formation of CuIII and is catalyzed by this species through a mediated electron transfer. Also, the modified electrode was stable for three weeks in dry conditions after repetitive measurements.

A chemically modified carbon paste electrode (MCPE) with tetrachloro-orthobenzoquinone(TOB) was employed to study the electrocatalytic oxidation of sulfite in aqueous solution using cyclic voltammetry (CV) and double-potential step chronoamperometry. It has been found that under an optimum condition (pH 2.0), the oxidation of sulfite at the surface of MCPE occurs at a potential of about 700 mV less positive than that of an unmodified CPE. The diffusion coefficient (D) for sulfite was found as 8.2×10-6 cm2 s-1 by chronoamperometry. The electron transfer coefficient, a, was estimated to be 0.4 and 0.24 for the oxidation of sulfite at the surface of MCPE and unmodified CPE, respectively. The electrocatalytic oxidation peak currents showed a linear dependence on the sulfite concentration in the range of 1×10-4 M -4.2×10-3 M with detection limit (3s) 5.7×10-5 M by CV. This method was also used for selective determination of sulfite in weak liquor.

The advantageous features of polymer modification and dispersion of metallic particles into the organic polymer was studied by construction of poly ortho-anisidine (POA) film and Ni(ΙΙ) were used in combination with POA films by immersion of the glassy carbon modified electrode in Nickel ions solution. This modified electrode exhibits good electrocatalytic activity toward the electrooxidation of hydrazine and has been studied by cyclic voltammetry (CV) and chronoamperometry techniques. The oxidation of hydrazine is occur at a potential about 140 mV less positive than that at unmodified electrode. The electron transfer coefficient (α) was determined and the electrocatalytic oxidation peak current of hydrazine showed a linear dependent on the hydrazine concentration and a linear calibration plot were obtained in the range of 5×10-5 M-1.4×10-2 M with cyclic voltammetry method. The detection limit (2σ) were determined as 3.9×10-5 M.

This paper reports the selective determination of carbidopa (CD) in the presence of uric acid (UA) using 2,7-bis(ferrocenyl ethyl)fluoren-9-one modified carbon nanotube paste electrode (2,7-BFCNPE) in 0.1 M phosphate buffer solution (PBS) pH 7.0. In PBS of pH 7.0, the oxidation current increased linearly with two concentration intervals of CD, one is 0.2 to 22.0 μM and, the other is 22.0 to 750.0 μM. The detection limit (3σ) obtained by DPV was 68.0 nM. The practical application of the modified electrode was demonstrated by determining CD in urine samples.

Electrooxidation of 4-chlorocatechol at a glassy carbon electrode (GCE) was investigated in the presence of some biologically important thiols (RSH), e.g. Dpenicillamine (D-PA), glutathione (GSH) and L-cysteine (L-Cys) in aqueous media using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and double step potential chronoamperometry methods. The 4-chlorocatechol exhibits strong electrochemical response toward thiols oxidation in wide pH rang (2.00–9.00). The results show that thiol-containing compounds participate in Michael addition reactions with 4-chlorocatechol to form the corresponding thioquinone derivatives. The reoxidation of the adduct leads to an increase in the anodic current. Therefore, in the optimum condition (pH=6.00) in CV, the oxidation of D-PA, GSH and L-Cys in the presence of 4-chlorocatechol occur at a potential about 420, 750 and 420 mV, respectively less positive than that in the absence of it. The kinetic parameters such as electron transfer coefficient, α and electrochemical reaction rate constant, kh was determined using electrochemical approaches.