Person: SARIOĞLU, CEVAT
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SARIOĞLU
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Publication Metadata only Photocatalytic-electrocatalytic dual hydrogen production system(PERGAMON-ELSEVIER SCIENCE LTD, 2016) ÖZKAYA, ALİ RIZA; Aydemir, Mehmet; Akyuz, Duygu; Agopcan, Burag; Sener, M. Kamm; Albayrak, Fatma Karaca; Sarzoglu, Ceuat; Koca, AtifIn this paper, in order to produce efficient and low cost hydrogen by using alternative energies with simple ways; a photocatalytic electrocatalytic dual hydrogen production system (PEHPS) which combined discontinuous photocatalytic and electrocatalytic systems in one continuous dual system was designed and optimized. In the photocatalytic chamber of PEHPS, nano-sized Cd(1-x)ZnxS/Pt photocatalysts were utilized. The synthesized Cd(1-x)ZnxS/Pt photocatalysts were characterized with scanning electron microscopy (SEM), X-Ray Diffraction (XRD) and diffuse reflectance UV Vis spectroscopy. The most active photocatalyst having CdZnS2 core and 10% Pt shell showed 24.0 mLg(-1) h(-1) (963.6 gmol g 1 h(-1)) hydrogen evolution rate with 4.01% solar energy conversion efficiency (SECE%). S2O3-2 produced in the photocatalytic chamber of PEHPS was used as redox species in the electrocatalytic chamber. This process decreased the cell potential of water electrolysis from 2.50 V to 1.70 V on glassy carbon electrodes. Moreover, usage of electro-polymerized metallophthalocyanines (Poly-MPc) as cathode active electrocatalyst, the over-potential of cathode of the electrocatalytic chamber for hydrogen reduction reaction decreased by 0.230 V. (C) 2015 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Fabrication and characterization of novel iodine doped hollow and mesoporous hematite (Fe2O3) particles derived from sol-gel method and their photocatalytic performances(ELSEVIER SCIENCE BV, 2018) SARIOĞLU, CEVAT; Demirci, Selim; Yurddaskal, Metin; Dikici, Tuncay; Sanoglu, CevatIn this work, iodine (1) doped hollow and mesoporous Fe2O3 photocatalyst particles were fabricated for the first time through sol-gel method. Phase structure, surface morphology, particle size, specific surface area and optical band gap of the synthesized Fe2O3 photocatalysts were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), BET surface analysis, particle size analyzer and UV-vis diffuse reflectance spectrum (UV-vis DRS), respectively. Also, electrochemical properties and photoluminescence spectra of Fe2O3 particles were measured. The results illustrated that high crystalline, hollow and mesoporous Fe2O3 particles were formed. The optical band gap values of the Fe203 photocatalysts changed between 2.104 and 1.93 eV. Photocatalytic efficiency of Fe2O3 photocatalysts were assessed via MB solution. The photocatalytic activity results exhibited that I doping enhanced the photocatalytic efficiency. 1% mole iodine doped (I-2) Fe2O3 photocatalyst had 97.723% photo degradation rate and 8.638 x 10(-2) min(-1) kinetic constant which showed the highest photocatalytic activity within 45 min. Moreover, stability and reusability experiments of Fe2O3 photocatalysts were carried out. The Fe2O3 photocatalysts showed outstanding stability after four sequence tests. As a result, I doped Fe2O3 is a good candidate for photocatalysts. (C) 2017 Elsevier B.V. All rights reserved.Publication Metadata only A new sulfur source for the preparation of efficient Cd(1-x)ZnxS photocatalyst for hydrogen evolution reaction(PERGAMON-ELSEVIER SCIENCE LTD, 2018) KOCA, ATIF; Agopcan, Burag; Akyuz, Duygu; Karaca, Fatma; Sarioglu, Cevat; Koca, AtifCd(1-x)ZnxS hexagonal crystals were for the first time synthesized via thermal sulfurization of Cd(1-x)ZnxO particles by using the elemental sulfur as the sulfur source. A temperature profile in the tube furnace was designed to obtain the proposed particle size, crystal structure, and morphology. Synthesized Cd(1-x)ZnxS particles were characterized with scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflectance UV Vis spectroscopy. It was seen that there was a polynomial relationship between the band gap and Cd: Zn ratio in the Cd(1-x)ZnxS. Cd0.58Zn023S has shapeless particles between 250 and 500 nm particle size. It was observed that particle size decreased as Zn ratio increased in the Cd(1-x),ZnxS. Cd(1-x),ZnxS hexagonal crystals had nano step surfaces which were one of the desired factors for achieving high photocatalytic efficiency. Finally, Synthesized Cd(1-x.)ZnxS particles were used as photocatalysts for the photocatalytic hydrogen evolution reaction (HER). Cd0.77Zn0.23S structure behaved the most active one among the different compositions of Cd(1-x)ZnxS nanoparticles. Cd0.77Zn0.23S showed almost high photocatalytic activity for HER with 1927 mu mol g(-1) h(-1) hydrogen evolution rate without using noble co-catalyst such as platinum. This good photocatalytic activity was believed to be due to the nanostep surface structure Cd0.77Zn0.23S which led the separation of the reduction and oxidation reaction sites and inhibited the recombination of the generated electrons and holes. Observation of considerably high photocurrent and open circuit potentials and changes in the electrochemical impedance spectroscopy responses supported the photocatalytic activity of the Cd0.77Zn0.23S particles. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Solar-hydrogen production with reduced graphene oxide supported CdxZn1-xS photocatalysts(PERGAMON-ELSEVIER SCIENCE LTD, 2020) ÖZKAYA, ALİ RIZA; Tanisik, Irem; Uguz, Ozlem; Akyuz, Duygu; Ayaz, Rana Muhammad Zunain; Sarioglu, Cevat; Karaca, Fatma; Ozkaya, Ali Riza; Koca, AtifReduced graphene oxide (RGO)/CdxZn(1-x)S composites were firstly synthesized by thermal sulfurization method in one pot with elemental sulfur as sulfur source. By using one pot synthesis, CdxZn(1-x)S particles were decorated on the RGO sheets during sulfurization of Cd2+ and Zn2+ precursors. This synthesis method eased the control of the particle sizes of CdxZn(1-x)S by providing homogenous decoration of RGO with CdxZn(1-x)S particles and increased the strength between RGO sheet and CdxZn(1-x)S particles, which enhanced charge carrier mobility rate. Here, RGO in the composite structure supplied high electron conductivity, high adsorption capacity and extended light absorption ability. Thus, prepared RGO/CdxZn(1-x)S composites enhanced the photocatalytic activity. The crystal systems, lattice parameters, band gaps and surface morphologies of all photocatalysts are characterized to determine the factors that affected the photocatalytic activities of the composites. After that, the photocatalytic activities of prepared photocatalysts were tested by measuring H-2 evolution rates. Among the composites, RGO/Cd0.7Zn0.3S structure possessed the highest H-2 production rate (141.6 mu molh(-1)) and apparent quantum efficiency (19.4%). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.