بررسي ميزان جذب هيدروژن در نانو كامپوزيت هاي پالاديوم

چكيده انگليسي :

Investigation of hydrogen adsorption on palladium poly aniline composites Mohammad Zhiani Majid Menati Department of Chemistry Isfahan University of Technology Isfahan 84156 83111 Iran E mail address m zhiani@cc iut ac ir M Zhiani Abstract In this study in order to investigation of hydrogen adsorption on palladium poly aniline nano composites three different nano composite was prepared To prepare these nanocomposites poly aniline nano fibers was synthesized by cyclic Voltammetery potantiostate and galvanostate method on GC electrode Then amount of hydrogen adsorption on these nano composites and their stability by means of cyclic Voltammetery method was measured and compared whit poly Aniline Pd GC electrode Also in our study Effect of isopropyl alcohol and cyclopentanon as a solvent for making and palladium Polyaniline nanocomposites was investigated there are two methods for making composites of palladium poly aniline The first is the use of poly aniline as a substrate In this method the palladium nano particles by electro deposition precipitate on the polymer substrate Second method is electro polymerization synthesis of poly aniline on electrodes containing palladium nano particles In this work we have studded prepare of nano fiber poly aniline by electro polymerization on the Pd C GC electrode cyclopentenon and isopropyl alcohol from the solvent used to prepare the catalyst ink the use peak increases electro chemical impedance spectroscopy EIS was used to study the characteristics of catalyst conductivity electrode porous structures and charge transfer at the catalyst electrolyte interface The results of EIS can apply useful information for fabrication electrodes Result shows that PANI synthesis on Pd GC electrode shifts potential oxidation of Pd H towards negative potential also increase amount of hydrogen adsorption on the catalyst and too increase stability of catalyst In addition EIS curves exhibit that PANI Pd GC display more conductivity than Pd GC The relative thermal stability of each polymer was studied using thermo gravimetric analysis TGA The TGA results obtained from PANI show that the method of synthesis is important in determining the thermal stability of the polymer but the oxidation state of the polymer is not very important A three step decomposition process for the protonated conducting form has been proposed by previous workers They suggest that the initial stages of weight loss are due to the volatilization of water molecules then at higher temperatures the protonic acid component of the polymer is lost and finally at more extreme temperatures the degradation of the polymer can lead to production of gases such as acetylene and ammonia in order to achieve an inexpensive tolerable anode catalyst for direct methanol fuel cell applications a composite of polyaniline PANI Nano fibers and Pt C Nano particles indicated by PANI Pt C was prepared by in situ electropolymerization of aniline and trifluoromethane sulfonic acid on the glassy carbon The effect of synthesized PANI nanofibers in methanol electrooxidation reaction was compared by bare Pt C by different electrochemical methods such as cyclic voltammetry CV electrochemical impedance spectroscopy and chronoamperometry Scanning electron microscopy SEM was also employed to observe the morphology of themodified catalyst layer The test results reveal that introduction of PANI Nanofibers within catalyst layer improve the catalyst activity in methanol oxidation hinder and prevent catalyst from more poisoning by intermediate products of methanol oxidation and improve the mechanical properties of the catalyst layer SEM images are also indicate that Porous PANI Nano fibers make good electrical juctions between platinum particles and anchor platinum particles and alleviate the Pt migration during methanol electrooxidation Keywords Palladium poly aniline nanocomposite Palladium nanoparticle Hydrogen adsorption

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بررسي ميزان جذب هيدروژن در نانو كامپوزيت هاي پالاديوم - پلي آنيلين

پلي آنيلين