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Dehaghi S.M.,Islamic Azad University at Tehran | Mobtaker H.G.,Islamic Azad University at Tehran | Ahmadi S.J.,Jaber Ibn Hayan Research Laboratory | Azar P.A.,Islamic Azad University at Tehran
Fresenius Environmental Bulletin | Year: 2012

Photocatalytic activity of metal ion-doped TiO2 under UV light irradiation for degradation of methylorange as a model was investigated. The catalysts were prepared by titanium tetraisopropoxide (TTiP) and dopant ions of Ag+, Cu2+, Ni2+, and Nd3+, via sol-gel method and hydroxypropyl cellulose (HPC) was used as dispersant. Metal nitrates in mole ratio of 1:1000 were added as dopants. The synthesized catalysts were characterized using XRD, TEM, XRF and BET analyses. Crystal sizes for TiO2 and Nddoped TiO2 were calculated to be about 45 and 35 nm, respectively, using Scherrer equation. Crystallinity of the catalyst has a reverse relation with the calcination temperature. Degradation process leads to final decomposition of methylorange indicator, confirmed by UV-VIS spectrometry and LC-MS. TiO2/Nd was the best photocatalyst; so, its photocatalytic properties were compared with TiO2 in photochemical (P) and coupled systems: electro-photochemical (EP), magnetic-photochemical (MP) and ultrasonic-photochemical (UP) systems studied at two pH values. Results of comparison for base catalyst (TiO2) and doped catalyst (TiO 2/Nd) in all systems revealed that the electro-photochemical degradation at pH 4 was the best coupled system.

Golikand A.N.,Jaber Ibn Hayan Research Laboratory | Golikand A.N.,CAS Shenyang Institute of Metal Research | Asgari M.,Jaber Ibn Hayan Research Laboratory | Lohrasbi E.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2011

Multi-walled carbon nano-tube supported Pt-Pd nanoparticles catalysts were prepared using NaBH4 as a reducing agent in either KOH or water for use as a cathode catalyst in polymer electrolyte membrane fuel cells (PEMFCs). X-ray diffraction (XRD) showed that compared to catalyst prepared in the absence of KOH, other catalyst has smaller particle sizes. Using the resulting multi-walled carbon nano-tube supported Pt-Pd catalysts, the catalyst particle size affects on the kinetics of the oxygen reduction reaction (ORR) were analyzed using cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. From RDE voltammetric studies, it was found that for both catalysts; the number of electrons, n, involved in the ORR was nearly four at potential 0.3 V versus Ag/AgCl (3 M KCl). Results also showed that the 2-step four electron reduction of O2 to H2O precede more favorably on the catalyst with smaller particle size. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Raoof J.B.,University of Mazandaran | Golikand A.N.,Jaber Ibn Hayan Research Laboratory | Baghayeri M.,University of Mazandaran
Journal of Solid State Electrochemistry | Year: 2010

Nickel-salophen-modified glassy carbon electrodes prepared by transferring one drop of Ni-salophen complex solution on the electrode surface. This modified electrode has been used for the electrocatalytic oxidation of methanol in alkaline solutions with various methods such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The electrooxidation was observed as large anodic peaks, and early stages of the cathodic direction of potential sweep around 20 mV vs. Ag| AgCl|KCl sat. A mechanism based on the electrochemical generation of Ni (HI) active sites and their subsequent consumptions by methanol have been discussed. EIS studies were employed to unveil the charge transfer rate as well as the electrical characteristics of the catalytic surface. For the electrochemical oxidation of methanol at 5.0 M concentration, charge transfer resistance of nearly 0.936 κΩ was obtained, while the resistance of the electro-catalyst layer was about 111.6 Ω. © Springer-Verlag 2009.

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