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Article Effects of Graphene Transfer and Thermal Annealing on Anticorrosive Properties of Stainless Steel(Amer Scientific Publishers, 2017) Oh, Jeong Hyeon; Han, Sangmok; Kim, Tae-Yoon; Park, Jongee; Ozturk, Abdullah; Kim, Soo YoungStainless steel (STS) films were annealed in a thermal quartz tube and covered with graphene to improve their anticorrosive properties. Graphene was synthesized via the chemical vapor deposition method and transferred onto the surface of the STS film by the layer-by-layer approach. The structure of the STS film changed from alpha-Fe to gamma-Fe after annealing at 700 C for 1 h, resulting in an increase of 82.72% in the inhibition efficiency. However, one-layer graphene acted as a conductive pathway and therefore deteriorated the anticorrosive properties of the STS film. To overcome this problem, graphene was transferred layer by layer onto the STS film. It was found that transfer of three layers of graphene onto the STS film resulted in a 91.57% increase in the inhibition efficiency. Therefore, thermal annealing and transfer of multilayer graphene are considered to be effective in enhancing the anticorrosive properties of STS films.Article Citation - WoS: 13Citation - Scopus: 14Control of the Crystal Growth Shape in Ch3nh3< Perovskite Materials(Amer Scientific Publishers, 2017) Le, Quyet Van; Shin, Jong Wook; Jung, Jin-Hee; Park, Jongee; Ozturk, Abdullah; Kim, Soo YoungCH3NH3PbBr3 (MAPbBr(3)) materials with perovskite structure were grown by a two-step process using Pb(CH3COO)(2). 3H(2)O and methyl amine bromide (MABr). By changing the concentration of MABr in isopropyl alcohol (IPA) solvent and the annealing temperature, the shape of CH3NH3PbBr3 materials can be controlled to afford nanocubes, nanowires, nanorods, and wrinkled structures. MAPbBr3 with single cubic structure was obtained at a MABr concentration of 3 mg/mL in IPA, and a nanorod array of MAPbBr3 was realized at a MABr concentration of 9 mg/mL in IPA at room temperature. Uniformly wrinkled shapes were formed after the synthesis temperature was increased to 60 and 90 degrees C. The X-ray diffraction patterns, Fourier transform infrared spectra, and X-ray photoelectron spectra of CH3NH3PbBr3 nanorods confirmed that the pure perovskite phase was obtained by dipping Pb(CH3COO)(2). 3H(2)O in MABr/IPA solution. The optical bandgap of the CH3NH3PbBr3 nanorods was estimated from the Tauc plot as 2.2 eV. The evolution of perovskite shapes is expected to lead to improvements in the electrical properties and surface contact, which are important factors for realizing high-performance devices.Article Citation - WoS: 10Alkaline Hydrothermal Synthesis, Characterization, and Photocatalytic Activity of Tio2 Nanostructures: the Effect of Initial Tio2 Phase(Amer Scientific Publishers, 2019) Erdogan, Nursev; Park, Jongee; Choi, Woohyuk; Kim, Soo Young; Ozturk, AbdullahOne-dimensional (1D) titanate nanostructures were synthesized by hydrothermal route, using commercially available TiO2 (P25) and anatase powders as precursor materials and strong NaOH solution as catalyzer. The prepared titanates were calcined, followed by protonation to produce TiO2 nanostructures having enhanced photocatalytic and photovoltaic properties. The synthesized TiO2 1D nanostructures were characterized using field-emission scanning electron microscope, high-resolution electron microscope, X-ray diffraction analysis, and UV-Vis photospectroscopy to understand the effect of initial TiO2 phase on morphological and crystallographic features, and bandgap. Methylene blue degradation test was applied to evaluate the photoactivity of the products obtained after different stages of the process. The findings indicate that 1D TiO2 nanostructures form by different mechanisms from dissolved aggregates during hydrothermal process, depending on the crystal structure of the initial precursor used. Photocatalytic test results reveal that protonated titanates have considerable adsorption capability, while photocatalytic degradation depends on TiO2 transformation.

