Browsing by Author "Ebadi, Mehdi"

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Citation - WoS: 17
Citation - Scopus: 15
Efficient synthesis of perovskite-type oxide photocathode by nonhydrolytic sol-gel method with an enhanced photoelectrochemical activity
(Elsevier Ltd, 2018) Taymaz Tabari; Mehdi Ebadi; Dheerendra Singh; Başar Ca̧ǧlar; M. Barış Yağcı; Yagci, M. Baris; Tabari, Taymaz; Ebadi, Mehdi; Singh, Dheerendra; Caglar, Basar
The photoelectrochemical activity of PbTiO3 (PTO) for water splitting was studied by linear sweeping voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. The nanohydrolytic sol-gel method was used to synthesise a crystalline PbTiO3 perovskite nanoparticles. The physical and chemical properties of nanoparticles such as crystal structure surface area reducibility band gap energy particle morphology and size surface composition and valence states were investigated by X-Ray diffraction (XRD) BET temperature-programmed reduction (TPR) UV diffuse reflectance spectroscopy (UV-DRS) high resolution scanning and transmission electron microscopy (HR-SEM and HR-TEM) along with X-Ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). PTO nanoparticles showed pure crystallinity high surface area (14 m2/g) and high oxygen mobility. PTO has band gap energy of 2.66 eV which makes it active under visible light irradiation. Moreover nanoparticles vary in size and create a core-shell structure in a way that small particles surround large particles. The core-shell structure along with a free defected sites on the surface results in high photoelectrochemical activity for water splitting reaction. The I–V curve revealed that the PTO nanoparticles are a p-type electrode with the photocurrent efficiency of ≈19%. This suggests that the photoelectrode does not require external bias to initiate the water splitting and the reaction can be initiated simply by making a connection between the anode and the cathode. In addition a great stability is observed for PTO electrodes during the reaction as evidenced by no leaching to the reaction medium. © 2020 Elsevier B.V. All rights reserved.
Citation - WoS: 33
Citation - Scopus: 32
Microwave assisted synthesis of La1 - xCaxMnO3 (x=0- 0.2 and 0.4): Structural and capacitance properties
(ELSEVIER SCI LTD, 2017) Taymaz Tabari; Dheerendra Singh; Atalay Calisan; Mehdi Ebadi; Haman Tavakkoli; Basar Caglar; Calisan, Atalay; Tavakkoli, Haman; Tabari, Taymaz; Ebadi, Mehdi; Caglar, Basar; Singh, Dheerendra
The effect of calcium incorporation on the physicochemical and electrochemical properties of the LaMnO3 (LM) perovskites was studied via several techniques. Moreover a new microwave assisted method was used to synthesize La(1-x)Ca()M(x)nO(3)(LCM) perovskites with various calcium content (x = 0.2 and 0.4). Then the physicochemical properties of the materials such as crystal structure particle size surface area reducibility and band gap energy were investigated by X-ray Diffraction (XRD) High resolution Scanning and Transmission Electron Microscope (HR-SEM and HR-TEM) BET analysis Temperature-programmed Reduction (TPR) and UV-visible Diffuse Reflectance Spectroscopy (UV-VIS DRS). The increase in partial concentration of calcium resulted in a high specific surface area larger particle size and an enhanced reducibility along with an increase in the band gap energy. In addition cyclic voltammetry was applied to LM and LCM perovskites to determine the effect of calcium incorporation on the capacitance of the electrochemical cell. It showed that the capacitance decreases with the amount of Ca2+ incorporated into the LM structure. This effect is linked to the formation of Mn4+ which hinders the electron transfer in the structure. The decline in the charge transfer is revealed by the specific capacitance. Finally our findings showed that the microwave assisted method provides a green efficient and time-saving route for perovskite synthesis and the calcium incorporation induces a negative effect on the capacitance properties of the LM perovskites.