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S. Daneshvar E Asl, S. Kh. Sadrnezhaad,
Volume 37, Issue 2 (9-2018)
Abstract

Rutile-phase titanium dioxide nanorod arrays were prepared by the hydrothermal method. Then, anatase-phase nanoleaves were successfully synthesized on the nanorod arrays via mild aqueous chemistry. Nanorod arrays scanning electron microscopy revealed that the thin film is uniform and crack free and the average diameter and height of the nanorods are 90 nm and 2 µm, respectively. Furthermore, nanorods are vertical to the substrate surface and have desired coverage density due to the predeposition of TiO2 seed layer which leaded to decrease the surface roughness of the substrate. Nanoleafed nanorods scanning electron microscopy indicated that the nanoleaves were grown uniformly on the entire surface of nanorods and the specific surface area and roughness factor of those are significantly improved. Energy dispersive spectrums suggested that F- and Cl- ions are partially doped into TiO2 crystals. Raman and X-ray spectra confirmed the formation of anatase-phase nanoleaves on the rutile-phase nanorods. X-ray diffraction also indicated that the nanorod arrays are highly oriented with respect to the substrate surface. The diffused reflectancetransmittance data revealed the incident light was more efficiently harvested by the nanoleafed nanorod thin film and the values of energy gap are 2.78 and 2.82 eV for rutile TiO2 nanorod and rutile+anatase TiO2 nanoleafed nanorod thin films, respectively. Synthesized nanostructure, having improved charge separation and transfer (due to the presence of the surface anatase/rutile junctions), high specific surface area and light harvesting (due to the presence of the nanoleaves) and low band gap energy (due to the nonmetallic elements doping), is viable alternative to traditional single crystalline TiO2 nanorods for highly efficient photoelectrochemical applications.

M. Toorani Farani,
Volume 39, Issue 1 (5-2020)
Abstract

In this study, Plasma Electrolytic Oxidation (PEO) at three frequencies of 500, 1000 and 3000 Hz was applied on Mg surface and the effect of PEO surface preparation on protective behavior of three types of epoxy, fusion bond epoxy (FBE) and polyurethane coatings was investigated. The microstructural and protective properties of PEO coatings were studied by SEM, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the coating formed at frequency of 3000 Hz had smaller pore size and better protection properties. EIS test in 3.5 Wt.% NaCl solution was also used to investigate the protective behavior of the two-layered coatings. The results showed that PEO process had a favorable effect on the protective behavior of the polymer layers. Moreover, the best protection behavior was related to the PEO/FBE coating system.

R. Bagheri, F. Karimzadeh, A. Kermanpur , M. Kharaziha,
Volume 40, Issue 2 (9-2021)
Abstract

A new method has been presented for the synthesis of copper (Cu)/copper oxide (CuO)-nanoparticles (NPs), based on the process of corrosion and oxidation of Cu-NPs on the surface of the gold electrode by nitric acid. Cu-NPs were deposited on the surface using potentiometric method. The high concentration of Cu-NPs was estimated by Differential Pulse Voltammetry (DPV). The process of growth and distribution of CuO-NPs on the surface of Cu-NPs using structural analysis of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) showed that nitrate was well absorbed and a sharp hydroxyl peak appeared and a phase of CuO NPs formed on the electrode surface. The surface morphology indicated that the average size reduced from about 150 nm to 50 nm in the presence of nitrate. This can be due to the oxidation of Cu nanoparticles on the surface and reduction of particle size compared to the absence of nitric acid. This simple and low-cost method can be used as a surface modification of antibacterial and active catalyst electrodes.


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