Search

A composite electrode comprised of graphite, Nujol, and nanoparticles of FeO core-cobalt hexacyanoferrate shell was prepared and the charge transport processes in the bulk of this composite were studied. The electrode/solution interface was assumed as a binary electrolyte whose charge transport occurred between redox sites of the nanoparticles present in the composite and counter cations present in the solution. Using cyclic voltammetry, the diffusion of counter cation in the shell was investigated. Using chronoamperometry, an effective diffusion coefficient and its dependency on the applied potential was obtained. In the Nyquist diagrams, different time constants were appeared with relation to different physical and electrochemical processes. Percolation of electron in the shell of the nanoparticles appeared at very high frequencies and exhibited the feature of a diffusion process with a transmissive boundary condition at interface of core-shell structure/graphite particles. The diffusion coefficients of electron and counter cation and the standard rate constants of each individual electrochemical reaction were obtained. [ABSTRACT FROM AUTHOR]

The electrooxidation of Gabapentin was studied on nanotubes of nickel oxide-modified carbon paste electrode for the first time. Cyclic voltammetry was employed to investigate the electrooxidation process. A simple, sensitive, and efficient amperometric method was developed for the analysis of the drug, and the corresponding analytical parameters were reported. For Gabapentin, a detection limit of 0.3 μM was obtained in a linear range of 2.4-50 μM. The proposed amperometric method was also applied to the analysis of commercial capsules, and the results were in good agreement with the declared values. Also, the applicability of the method to the direct assay of the drug in human serum and urine was described. [ABSTRACT FROM AUTHOR]

Nanoparticles of lithium cobalt oxide (LiCoO) and nanosheets of lithium vanadium oxide (LiVO) were synthesized by a citrate sol-gel combustion route. The physical characterizations of the electrodic materials were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also X-ray diffraction (XRD) measurements. Near spherical nanoparticles of ≈100 nm and compact nanosheets with a few nanometers thick were observed by SEM and TEM for LiCoO and LiVO, respectively. XRD data indicated that the as-prepared active materials presented pure phase of rhombohedral LiCoO with R-3m symmetry and monoclinic LiVO with p2/m symmetry. The kinetics of electrochemical intercalation of lithium ion into the nanoparticles of LiCoO and nanosheets of LiVO from 1.0 mol l LiNO aqueous solution were investigated by cyclic voltammetry and chronoamperometry. An aqueous rechargeable lithium-ion battery consisting of LiCoO nanoparticles as positive and LiVO nanosheets as negative electrode was assembled. This battery represented a discharge voltage of about 1 V with good cycling performance. [ABSTRACT FROM AUTHOR]

The electrooxidation of dextromethorphan on a composite constructed with carbon nanotube–ionic liquid–carbon microparticles was investigated by cyclic voltammetry in a 100 mM phosphate buffer solution, pH 7.40. In the voltammograms, an irreversible diffusion-controlled anodic peak appeared. The diffusion coefficient of dextromethorphan, the electron-transfer coefficient, and the standard rate constant of the electrooxidation process were found to be 3.45 × 10−6 cm2 s−1, 0.65, and 1.67 × 10−3 cm s−1, respectively. A sensitive and timesaving determination procedure was developed for the analysis of dextromethorphan, and the corresponding analytical parameters were reported. Using this method, dextromethorphan was determined with an LOD and LOQ of 8.81 and 29.36 μM in a linear range of 2.5 × 10−4 to 3.3 × 10−3 M, respectively. The proposed amperometric method was successfully applied to the analysis of commercial pharmaceutical products (syrup and oral drop), and the results were in good agreement with the declared values. [ABSTRACT FROM AUTHOR]