9044

8389

كارشناسي ارشد

ماده چگال

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1392

96ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

مهدي رنجبر

پرويز كاملي

26/3/93

اسماعيل عبدالحسيني سارسري، جواد هاشمي فر

فيزيك

ID8389

97 Preparation of colloidal tungsten oxide nanoparticles and investigation of their gasochromic properties Amir Heidari fini amir heidari@ph iut ac ir 2014 02 05 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr Mehdi Ranjbar ranjbar@cc iut ac ir Abstract By a wide energy gap tungsten Oxide is a semiconductor with significant chromogenic features Thismetallic oxide has also so many properties such as electrochromic and become applicable as photocatalyst andgas sensor Among these properties its chromogenic one in the presence of hydrogen gas is really significant Nowadays hydrogen as a clean and renewable fuel is considered as an alternative for fossil fuels for home industrial and specifically in transportation consumptions An important note in usage of this gas is its extremeflammability in range of 4 to 75 percent of combination with the air Since tungsten oxide change its color whilebeing exposed to the hydrogen we can use it as a hydrogen gas sensor Through this thesis the colloidnanoparticles of tungsten oxide are produced by electrolysis approach In order to make these nanoparticlessensitive to hydrogen palladium catalyst is added to the solution achieved by electrolysis with the concentrationof Nanoparticles powder of these samples was produced and it was tried to find their structures chemical bounding and morphologies The X ray diffraction XRD spectrum determined the crystallographicstructure of the sample and this analysis showed that the nanoparticles are tungsten oxide dihydrate Dehydration and formation of monoclinic was obtained By annealing these powders at and Chemical properties of samples were studied by analysis of fouriertransmission Infra red FTIR and X ray photoelectron spectroscopy XPS These analyses have shown theelimination of water molecules bounding and hydroxyl group from the sample and formation of completely oxideones after the annealing process The field emission scanning electron microscope FE SEM pictures revealedthe formation of plate like morphology in some parts Optical properties of the colloid solution was measured byspectrophotometer UV Vis in range of The effect of palladium concentration and the time ofelectrolysis on gasochromic process are shown significantly through its results and it is shown that application ofspecific amount of palladium would enhance the gasochromic process Also different absorption peaks wereobserved at and in the spectrum in the presence of hydrogen gas Each of these peaksbelonged to the specific color centers which are known as bulk paramagnetism surface paramagnetism andsurface diamagnetism respectively Keywords Tungsten oxide Electrolysis Gasochromic properties Palladium catalyst Annealingtemperature Hydrogen reduction

مهدي رنجبر

پرويز كاملي

اسماعيل عبدالحسيني سارسري، جواد هاشمي فر