behjat deiminiat

A novel photoelectrocatalyst composed from multiwalled carbon nanotubes (MWCNTs), titanium dioxide (TiO2) and gold-platinum bimetallic nanoparticles (Au–PtNPs) was prepared on the surface of a fluorine-tin oxide (FTO) electrode and it was used for electrooxidation of ethanol molecules. Multiwalled carbon nanotubes were utilized as the catalyst support to improve the electrical transmission. The TiO2 nanoparticles were transferred onto the surface of MWCNTs/FTO modified electrode and then, the surface of the electrode was coated with gold-platinum nanoparticles. The surface morphology and chemical composition of the prepared Au-Pt/TiO2/MWCNTs photoelectrocatalyst were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The fabrication process of the photoelectrocatalyst was investigated by cyclic voltammetry and chronoamperometry techniques. The exchange current densities (J0) were calculated for Pt/FTO, Pt/MWCNTs/FTO, Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNT/FTO electrodes and they were found to be:  4.10 × 10-5, 6.06 × 10-5, 1.45 × 10-4 and 1.89 × 10-4 mA cm-2, respectively. Also, the values of J0 for Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNTs/FTO in the presence of light were obtained 2.0 × 10-4 and 5.1 × 10-4 mA cm-2, respectively. The obtained results reveal that the Au-Pt/TiO2/MWCNTs/FTO electrode has the higher J0 value in the presence of UV-Vis light and the light irradiation can accelerate the ethanol oxidation process. The experimental results showed that the proposed photoelectrocatalyst has an excellent catalytic activity for oxidation of ethanol molecules under the UV-Vis light irradiation which is due to the synergistic effect between the TiO2 photocatalyst and gold-platinum electrocatalyst.

In this research project, a sensitive electrochemical sensor was developed for simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA) based on a gold electrode modified with functionalized multi-wall carbon nanotubes/graphene oxide (f-MWCNTs/GO) nanocomposite capped with gold nanoparticles (AuNPs). The modified electrode showed excellent electrocatalytic activity for the oxidation of DA and PA molecules in aqueous solutions with well-separated oxidation peaks for each species. The fabrication process of the proposed sensor was evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Cyclic voltammetry (CV) and also electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of f-MWCNTs/GO/AuNPs/AuE. Under the optimized experimental conditions, the calibration curves were linear over the concentration ranges of 1-400 µM with a detection limit of 0.5 and 0.3 µM for DA and PA, respectively. Finally, the constructed electrode was successfully applied for the quantitative measurement of dopamine and paracetamol in pharmaceutical and urine samples.

A new nanocatalyst was prepared using montmorillonite (MMT) clay mineral as a low-cost substrate incorporation with platinum and osmium nanoparticles for electrocatalytic oxidation of methanol molecules. The morphology and microscopic structure of the nanocomposite film formed at the surface of the fluorine tin oxide (FTO) electrode, were characterized by scanning electron microscopy and energy dispersive X-ray analysis. The electrocatalytic activity of the Pt-Os/Clay/FTO modified electrode was compared with Pt/FTO and Pt/Clay/FTO electrodes using cyclic voltammetry and chronoamperometry techniques and it was found that the Pt-Os/Clay/FTO electrode has a better performance for oxidation of methanol molecules. The exchange current density (J0) values for Pt/FTO, Pt/Clay/FTO and Pt-Os/Clay/FTO were calculated using the Tafel equation and they were found to be: 2.48×10-6, 4.01×10-6 and 8.45×10-6 mA cm-2, respectively. The results indicate that the purposed electrode accelerates significantly the process of methanol electrooxidation. The effects of various parameters on the electro-oxidation of methanol molecules were investigated and the obtained experimental results were discussed. The new modified electrode, showed a significant electrocatalytic activity for methanol electrooxidation over the other Pt-modified electrodes.