2011 YÜksek lisans tez özetleri

Synthesıs And Characterızatıon Of Photocatalysts And Photocatalytıc Hydrogen Productıon

The studies on photocatalytic hydrogen production as a renewable energy holds an important place, especially those studies using visible region of sunlight in conjuction with semiconductors for the production of hydrogen from water. Photocatalytic systems can produce H₂ from water using special semiconductor materials and energy from sunlight wide band-gap semiconductors, such as, sensitized TiO₂, are the most promising and the most widely studied material in the field of solar hydrogen conversion.

Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the rapid recombination of photo-generated electron/hole pairs as well as backward reaction and the poor activation of TiO2 by visible light. Some investigators studied the effects of addition of sacrificial reagents and carbonate salts to prohibit rapid recombination of electron/hole pairs and backward reactions. Other research focused on the enhancement of photocatalysis by modification of TiO2 by means of metal loading, metal ion doping, dye sensitization, composite semiconductor, anion doping.

This thesis focuses on synthesis of anion and metal doped TiO2 photocatalysts and using these photocatalysts for hydrogen production from water splitting reaction using methanol as hole scavanger. Also photocatalytic activity of these photocatalysts were tested with methylene blue degradation reaction. The charactrization of these photocatalysts were carried out by XRD and DRS.

Nitrogen-doped titanium oxide powders were synthesized by wet method and used as a support for various metals such as Fe, Cr, Ni, Cu and Pt toward photocatalytic hydrogen evolution. Aqeous solutions of metal salts were used as a metal source and metals were reduced on N-TiO₂ powders with hydrazine hydrate solutions. Also Ni-N-TiO₂ catalysts with different nickel concentration were synthesized in this study. We examined photocatalytic activities of these synthesized photocatalysts by water splitting reaction under visible ligth. Pt-N-TiO₂ photocatalyst showed the best photocatalytic activity; but the H₂ production rate of Pt-N-TiO₂ increases for 2 h of reaction. After 2 hours, hydrogen production rate was fixed by the end of the reaction but the H₂ production rate of Ni-N-TiO₂ increases during the reaction. In other words, Ni-N-TiO₂ was more stable than Pt-N-TiO₂.
  

ARDA Begüm

Danışman : Y. Doç.Dr. Işıl ACAR

Anabilim Dalı : Kimya Mühendisliği

Programı : Kimyasal Teknolojiler

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Yard. Doç. Dr. Işıl ACAR

Prof. Dr. Saadet PABUCCUOĞLU

Doç. Dr. Gamze Güçlü

Doç. Dr. Hüseyin DELİGÖZ

Yard. Doç. Dr. Aliye ARABACI