Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Preparation and Characterization of Mixed Chalcogenide Electrocatalysts and

Their Use In Various Reactions
Photocatalysis, using sunlight as an energy source, is an important technique in the removal of impurities in the water and in the production of hydrogen from water. In recent years, semiconductors because of optical and electronic properties, chemical behavior, are gaining importance as industrial catalysts. A semiconductor material, such as, CdS able to absorb visible wavelength, is promising photocatalyst for both hydrogen production with solar energy and the removal of impurities in water. However, CdS has an important problem about stability. Thus, to synthesize CdS showing high and stable activity is the goal of this thesis.
In this thesis, CdS nanoparticles sensitive to the visible region of the solar spectrum, synthesized using hydrothermal and chemical precipitation agents (Na₂S, TAA, TU, TG, TGA, etc.), using various metals (Ni, Co, Sb, Ce, Zn etc.) and synthesized as binary metal sulfides (MS-CdS). (MS = MoS₂, ZnS, Sb₂S₃, NiS, CoS). CdS showed hexagonal structure by using hydrothermal method and showed cubic structure by using chemical precipitation method.
Physical and chemical characterization methods, XRD, UV-Vis Reflectance, Photoluminescence, Particle Size Analysis, Cyclic Voltammetry, Linear Sweep Voltammetry, MTT and SEM were utilized for photocatalysts. Photocatalytic activity of the catalysts is determined via the removal of methylene blue from water under visible light. And also the catalysts, which had the best results from methylene blue degradation reaction, were coated on ITO glass and LSV measurement is used to get photocurrent values to determine the production rate of hydrogen.
Band gap values for single CdS and doped CdS catalysts evaluated approximately 2,4-2,6 eV. CTAB and TG doped CdS catalysts showed the highest activity in as-prepared catalysts with different doping agents. CdS-TG-Na₂S-CP catalyst has shown considerably high photocurrent value as 26 mA in the photoelectrochemical activity. CdS-CTAB-CP catalyst has shown maximum quantum yield value as 2,64 in as-prepared catalysts. Co metal for both preparation methods and activity tests has displayed the highest activity. The CdS catalysts in combination with MoS₂ as binary metal sulfides have reached the highest activity. At the same time mono MoS₂ catalyst has also reached high photocatalytic activity in the visible region.

KERKEZ Özge

Tez Adı : Nanoboyutta Şekilli Karışık Oksitlerin Hazırlanması ve Fotokatalitik

Aktivitelerinin İncelenmesi

Danışman : Prof. Dr. İsmail Boz

Anabilim Dalı : Kimya Mühendisliği

Programı : Proses ve Reaktör Tasarımı

Mezuniyet Yılı : 2013

Tez Savunma Jürisi : Prof. Dr. İsmail Boz

Prof. Dr. Mehmet Ali Gürkaynak

Prof. Dr. Erhan Demirbaş

Prof. Dr. Mahmut Bayramoğlu

Doç. Dr. Sevil Yücel