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SARIOĞLU, CEVAT

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Author: ÖZKAYA, ALİ RIZA × End date: 2019 ×

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    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, Atif
    In 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.
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    Metal chalcogenide based photocatalysts decorated with heteroatom doped reduced graphene oxide for photocatalytic and photoelectrochemical hydrogen production
    (PERGAMON-ELSEVIER SCIENCE LTD, 2019) ÖZKAYA, ALİ RIZA; Akyuz, Duygu; Ayaz, Rana Muhammad Zunain; Yilmaz, Seda; Uguz, Ozlem; Sarioglu, Cevat; Karaca, Fatma; Ozkaya, Ali Riza; Koca, Atif
    Heteroatom (N, B and P) doped reduced graphene oxide (RGO)-metal chalcogenide nanocomposites (RGO-Cd0.60Zn0.40S) were prepared by the solvothermal method, and then they were characterized with X-ray diffraction, Raman spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis diffuse reflectance spectroscopy and photoluminescence techniques. Doping of RGO with heteroatoms of N, B and P increased charge-transfer capability of nanocomposites and thus, improved both photocatalytic and photoelectrochemical hydrogen production activities of them. N-doped RGO-Cd0.60Zn0.40S photocatalyst exhibited the highest photocatalytic hydrogen production rate (1114 mu molh(-1) g(-1)) in photocatalytic (PC) system amongst other and it was 1.5 times higher than that of RGO-Cd0.60Zn0.40S photocatalyst. Having a current density of 0.92 mAcm(-2), photoelectrochemical hydrogen production activity of N-RGO-Cd0.60Zn0.40S electrode was found to be 3 times higher than RGO-Cd0.60Zn0.40S photoelectrode without any applied bias potential under visible light irradiation in photoelectrochemical system. In general, these results clearly showed that heteroatom doping of RGO led to promising materials for renewable hydrogen production in the photocatalytic and photoelectrochemical systems. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.