فهرست مطالب nahid farzaneh

In this study, graphene oxide was prepared by a modified Hummers’ method and used as support for dispersing of nanoparticles. SrCoO3-δ nanoparticles were prepared and characterized by X-ray diffraction technique. They were used accompanied by Pt nanoparticles on the reduced graphene oxide (RGO) support for preparing of Pt-SrCoO3-δ-RGO catalyst. Transmission electron microscopy images were used to show the morphology and distribution of nanoparticles. The catalytic activity of the prepared catalyst was investigated for methanol electrooxidation by cyclic voltammetry and electrochemical impedance spectroscopy techniques and compared with the catalytic activity of Pt-RGO catalyst. The effects of some experimental parameters affecting on methanol oxidation such as methanol concentration, temperature and scan rate were investigated on Pt-SrCoO3-δ-RGO catalyst and the optimum conditions were suggested. Pt-SrCoO3-δ-RGO catalyst showed better catalytic activity for methanol oxidation compared with Pt-RGO catalyst indicating that Pt-SrCoO3-δ-RGO can be used as a promising catalyst for application in direct methanol fuel cells.

Here, graphene oxide is synthesized and functionalized with methyl viologen and chitosan to be used as a novel catalyst support for Pt nanoparticles. The particle size and distribution of Pt nanoparticles are characterized by transmission electron microscope images. Pt nanoparticles with the mean particle size of 3.62 nm are dispersed on the support very uniformly. The catalytic activity of the prepared catalyst is investigated for methanol oxidation by cyclic voltammetry technique. The prepared catalyst showed very good catalytic activity for methanol oxidation. The experimental and statistical analyses are used to investigate the effect of mutual interaction between temperature and methanol concentration on anodic current density of methanol oxidation. The statistical analysis results reveals that the influence of temperature and methanol concentration as main factors and their reciprocal interactions are significant at α=0.05. Meanwhile, the results confirm that the response increases with both main factors. The enhancement of the anodic current density of methanol oxidation with temperature and methanol concentration is equal to 530.22% and 184.89%, respectively. Therefore, the effect of temperature on the response is higher than that of methanol concentration.

Here, metal nanoparticles were synthesized by chemical reduction of the corresponding metal salts in the presence of chitosan polymer. Binary and ternary metallic-chitosan Pt-Fe-CH, Pt-Co-CH and Pt-Fe-Co-CH nanocomposites were prepared. Transmission electron microscopy images and UV–Vis spectra of the nanocomposites confirmed the presence of the metal nanoparticles. The electrocatalytic activity of the nanocomposites for ethanol oxidation was tested by cyclic voltammetry, Liner Sweep Voltammetry, amperometric i-t curve and electrochemical impedance spectroscopy techniques. The effect of some experimental factors on ethanol oxidation was investigated. CO stripping was used to determine the CO tolerance of the catalysts for ethanol oxidation. Incorporation of small amounts of Co and Fe nanoparticles in the Pt-CH catalyst caused the higher activity of the catalyst for ethanol electrooxidation. The activation energy of Pt-Co-Fe-CH catalyst obtained from the Arrhenius equation was lower than other studied catalysts. These results showed that Pt-Fe-Co-CH catalyst has better catalytic activity for ethanol oxidation among all prepared catalysts.