• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.300-306
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• 2014

In this study, we investigated the noble metal catalysts for HCHO removal at room temperature. These catalysts were characterized by XRD, FT-IR, CO-chemisorption. As a result, Pt and Pd based catalysts prepared by the reduction treatment showed the superior HCHO oxidation ability at room temperature. When the catalysts were prepared using $TiO_2$ support, which is well known as the reducing support, showed the superior activity. Also, the activity decreased by the agglomeration of active metal with increasing the reduction time. In case of reduction catalysts, it has been confirmed that the desorption and adsorption ability properties of HCHO is excellent at room temperature.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.133-138
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• 2017

We investigated the interface defect engineering and reaction mechanism of reduced transition layer and nitride layer in the active plasma process on 4H-SiC by the plasma reaction with the rapid processing time at the room temperature. Through the combination of experiment and theoretical studies, we clearly observed that advanced active plasma process on 4H-SiC of oxidation and nitridation have improved electrical properties by the stable bond structure and decrease of the interfacial defects. In the plasma oxidation system, we showed that plasma oxide on SiC has enhanced electrical characteristics than the thermally oxidation and suppressed generation of the interface trap density. The decrease of the defect states in transition layer and stress induced leakage current (SILC) clearly showed that plasma process enhances quality of $SiO_2$ by the reduction of transition layer due to the controlled interstitial C atoms. And in another processes, the Plasma Nitridation (PN) system, we investigated the modification in bond structure in the nitride SiC surface by the rapid PN process. We observed that converted N reacted through spontaneous incorporation the SiC sub-surface, resulting in N atoms converted to C-site by the low bond energy. In particular, electrical properties exhibited that the generated trap states was suppressed with the nitrided layer. The results of active plasma oxidation and nitridation system suggest plasma processes on SiC of rapid and low temperature process, compare with the traditional gas annealing process with high temperature and long process time.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.326-331
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• 2021

In this study, the preparation conditions for a TiO₂-based vanadium-based catalyst for oxidizing hydrogen sulfide at room temperature were optimized. Four types of commercial TiO₂ were used as a catalyst support and the performance evaluation of hydrogen sulfide oxidation at room temperature of V/TiO₂ by varying vanadium contents prepared using the impregnation method was performed. Among the types of TiO₂ tested, it was confirmed that the catalyst with the vanadium content of 5% and based on TiO₂(A) has the best hydrogen sulfide conversion rate of 58%. By comparing the physical and chemical properties of the catalyst, the specific surface area of the support and the species of dominant vanadium are the major factor in catalyst performance. In order to confirm the regeneration characteristics of the catalyst with reduced activity, heat treatment was performed at 400 ℃ for 2 h, and the amount of hydrogen sulfide oxidation decreased by 10% due to the partial deposition of sulfur in the regenerated catalyst, but it was confirmed that the initial performance was similar.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.35-38
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• 2012

Room temperature oxidation of organic sulfides with polyvinylpyrrolidone-supported hydrogen peroxide (PVP-$H_2O_2$) in the presence of Mn(III) complexes of meso-tetraphenylporphyrin, Mn(TPP)X (X = OCN, SCN, OAc, Cl) and imidazole (ImH) leads to the highly chemoselective (ca. 90%) oxidation of sulfides to the corresponding sulfoxide. The efficiency of reaction has been shown to be influenced by different reaction parameters such as the nature of counterion (X) and solvent as well as the molar ratio of reactants. Using Mn(TPP)OCN and ImH in 1:15 molar ratio and acetone as the solvent leads to the efficient oxidation of different sulfides.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.87-93
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• 1985

The hematite the magetite and the maghemite thin film were prepared by oxidation and reductino of the vaccum-evaporated iron thin film. Interre;atoms between film preparation process and the electrical properties were investigated. At room temperature the electrical conductivity of the iron the hematite the magnetite and the maghemite thin film were $1{\times}10^4\Omega^{-1}cm^{-1}$, 2{\times}10^{-5}\Omega^{-1}cm^{-1}$, $3{\times}10^{-5}\Omega^{-1}cm^{-1}$, and $4{\times}10^{-5}\Omega^{-1}cm^{-1}$, resp-ectively. The surface of each thin film was dense and homogeneous. At the temperature that the iron thin film was converted into the hematite thin film the electrical conductivity decreased rapidly and the electrical con-ductivity of the hematite thin film increased as temperature increased. The hematite thin film was reduced to the magnetite thin film in H2 atmosphere. The electrical conductivity decreased rapidly at the temperature that the maghemite thin film is formed by oxidation of the magnetite thin film and the electrical conductivity of the maghemite thin film increased as temperature increased.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.221-229
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• 2017

In this study, a wet impregnation method was applied to catalysts based on the active metal Pt in order to confirm the oxidation characteristics of various commercial alumina supports at room temperature. The catalysts were characterized using XPS, CO-chemisorption, and BET. Various $Pt/Al_2O_3$ catalysts controlled the oxygen species of Pt by the electronegativity of electrons and charges when the catalyst was prepared according to the heat treatment conditions. The reason that the dispersion degree decreases with increasing Pt loading seems to be attributed to HT (Huttig Temperature) of Pt. In addition, the minimum hydrogen concentration that can be controlled at room temperature can control hydrogen from metallic Pt up to 1.0 vol% at over 70.09% in the catalyst.

• Korean journal of food and cookery science
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• v.11 no.2
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• pp.93-97
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• 1995

Effects of added ginger juice in Yackwa on the sensory quality and the lipid oxidation were studied. Also effects of soaking on the lipid oxidation were examined. There were no significant differences between Yackwa without adding ginger juice and ones with adding ginger juice on texture, shape, color. However, Yackwa, with ginger juice more than 1 tea spoon(1.5) of ginger juice per 1 cup of flour, was better than one without ginger juice on taste, flavor and overall acceptibility. Added ginger juice showed the antioxidant effect during frying in oil and storage at room temperature. The higher the amount of ginger juice was added, the slower of lipid oxidation was resulted in Yackwa. Yackwa soaked in syrup or in honey showed lower lipid oxidation than one without soaking during storage at room temperature. The antioxidant effect of soaking in honey was higher than one of soaking In syrup.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.471-476
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• 2003

Au/oxide/n-InP Schottky diodes were fabricated from heteroepitaxial InP layers grown on GaAs substrates by the metalorganic vapor phase epitaxy (MOVPE) method from a new combination of source materials: ethyldimethylindium (EDMIn) and tertiarybutylphosphine (TBP). Anodic oxidation technique by using a solution of 10 g of ammonium pentaborate in 100 cc of ethylene glycole as the electrolyte was used to deposit a thin oxide layer. The barrier heights determined from three different techniques, current-voltage (I-V) measurements at room temperature and in the temperature range of 273 K - 373 K, and room temperature capacitance-voltage (C-V) measurements are in good agreement, 0.7 - 0.9 eV which is considerably high as compared to the 0.45 - 0.55 eV in Au/n-InP Schottky diode without a Passivation layer. The ideality factors of 1.1 - 1.3 of the Schottky diodes were also determined from the I-Y characteristics. Deep level transient spectroscopy (DLTS) studies revealed only one shallow electron state at 92.6 meV below the bottom of the conduction band and no deep state in the heteroepitaxial InP layers grown from EDMIn and TBP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.98-103
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• 2013

The alumina substrates that Ni electrode was printed on and the multi-layered PTCR thermistors of which composition is $(Ba_{0.998}Ce_{0.002})TiO_3+0.001MnCO_3+0.05BN$ were fabricated by a thick film process, and the effect of re-oxidation temperature on their resistivities and resistance jumps were investigated, respectively. Ni electroded alumina substrate and the multi-layered PTC thermistor were sintered at $1150^{\circ}C$ for 2 h under $PO_2=10^{-6}$ Pa and then re-oxidized at $600{\sim}850^{\circ}C$ for 20 min. With increasing the re-oxidation temperature, the room temperature resistivity increased and the resistance jump ($LogR_{290}/R_{25}$) decreased, which seems to be related to the oxidation of Ni electrode. The small sized chip PTC thermistor such as 2012 and 3216 exhibits a nonlinear and rectifying behavior in I-V curve but the large sized chip PTC thermistor such as 4532 and 6532 shows a linear and ohmic behavior. Also, the small sized chip PTC thermistor such as 2012 and 3216 is more dependent on the re-oxidation temperature and easy to be oxidized in comparison with the large sized chip PTC thermistor such as 4532 and 6532. So, the re-oxidation conditions of chip PTC thermistor may be determined by considering the chip size.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.325-325
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• 2011

Very initial stage of oxidation process of Si (001) surface at room temperature (300 K) and high temperature (1200 K) was investigated using large scale molecular dynamics simulation. Reactive force field potential [1] was used for the simulation owing to its ability to handle charge variation as well as breaking and forming of bonds associated with the oxidation reaction. The results show that oxygen molecules adsorb dissociatively or otherwise leave the silicon surface. Initial position and orientation of oxygen molecule above the surface play important role in determining final state and time needed to dissociate. At 300 K, continuous transformation of ion $Si^+$ (or suboxide Si2O) to $Si2^+$ (SiO), $Si3^+$ (Si2O3) and finally to $Si4^+$ (SiO2) clearly observed. High temperature silicon surface provide heat energy that enable oxygen atom to penetrate into deeper silicon surface. The heat energy also retards adsorption process. As a result, transformation of ion $Si^+$ is impeded at 1200 K.