• Clean Technology
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• v.29 no.4
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• pp.313-320
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• 2023

In order to increase the usability of H₂-SCR, the NOx removal characteristics with catalyst powder of PtNi/CeO₂-W-TiO₂ using Ce as a co-catalyst was synthesized and coated on a porous metal structure (PMS) were evaluated. Catalyst powder of PtNi/CeO₂-W-TiO₂(PtNi nanoparticles onto W-TiO₂, with the incorporation of ceria (CeO₂) as a co-catalysts) was synthesized and coated onto a porous metal structure (PMS) to produce a Selective Catalytic Reduction (SCR) catalyst. H₂-SCR with CeO₂ as a co-catalyst exhibited higher NOx removal efficiency compared to H₂-SCR without CeO₂. Particularly, at a 10wt% CeO₂ loading ratio, the NOx removal efficiency was highest at 90℃. As the amount of catalyst coating on PMS increased, the NOx removal efficiency was improved below 90℃, but it was decreased above 120℃. When the space velocity was changed from 4,000 h^-1 to 20,000 h^-1, the NOx removal efficiency improved at temperatures above 120℃. It was expected that the use of the catalyst could be reduced by applying the PMS with excellent specific surface area as a support.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.423-428
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• 2010

To reduce polarization of electrochemical capacitor based on carbon nanotube, titanium oxide nanoparticles were deposited by ultrasound. The pore distribution of $TiO_2$/CNT nanoparticle exhibited surface area of $341\;m^2g^{-1}$ when $TiO_2$ content was 4 wt %, which was better than that of pristine CNT with surface area of $188\;m^2g^{-1}$. The analyses indicated that titanium oxide (particle diameter < 20 nm) was deposited on the CNT surface. The electrochemical performance was evaluated by using cyclic voltammetry (CV), impedance measurement, and constant-current charge/discharge cycling techniques. The $TiO_2$/CNT composite electrode showed relatively better electrochemical behaviors than CNT electrode by increasing the specific capacitance from $22\;Fg^{-1}$ to $37\;Fg^{-1}$ in 1 M $H_2SO_4$ solution. A symmetric cell assembled with the composite electrodes showed the specific capacitance value of $11\;Fg^{-1}$ at a current loading of $0.5\;mAcm^{-2}$ during initial cycling.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.227-233
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• 2009

Recently, dye-sensitized solar cell (DSSC), one of the solar cells, has been widely investigated. Studies on DSSCs can be classified into 4 fields such as $TiO_2$ nanocrystalline materials, dyes, electrolytes and conductive plate. In this work, $TiO_2$ nanoparticles for dye adsorption were synthesized, and added into the photo-electrode paste with different phosphor types and contents. Then, the influence of phosphor additives on the conversion efficiency of DSSCs was investigated. It was found that the maximum conversion efficiency was 8.81% when 0.5% of YAG phospher having the particle size of 400 nm was used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.97-102
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• 2004

용액 중에서 나노입자의 전기영동 특성을 이용한 전자종이용 잉크 제조를 위해 $TiO_2$ 나노입자를 저유전율 용매인 cyclohexane에 혼합한 후 용매와 용질의 비중차를 줄이기 위해 분말 상 polyethylen을 첨가하여 high energy milling의 방법으로 입자분쇄와 동시에 입자 표면에 고분자 풍을 코팅하였다. 용액내의 입자 분산성 향상과 용매 착색을 위하여 계면활성제와 oil-blue N을 첨가한 후 전자종이용 잉크를 제조하여 측정한 제타 전위 결과 cyclohexane 내에서 $TiO_2$의 제타전위는 -40mV 정도였으나 polyethylene으로 코팅한 후 계면활성제를 첨가하였을 경우 최대 -110mV 이상의 높은 값을 나타내었다. 실제 디스플레이 특성을 평가하기 위해 포토리소그래피를 이용하여 3인치 크기의 ITO glass 위에 $10{\mu}m$의 크기를 갖는 십자형의 격벽을 $40{\mu}m$의 높이로 균일하게 형성한 후 합성된 전자잉크로 주입하여 상부전극과 하부전극사이에 UV 경화제를 도포하여 UV 접합을 실시하였다. 격벽 내에서 입자의 mobility를 측정하여 환산된 전자잉크의 응답속도는 0.1cm/sec로 측정되었으나, 전기영동시 입자들의 움직임에 따른 반사광의 파형을 측정한 경우 0.07cm/sec의 응답속도를 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.271.1-271.1
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• 2013

Titania is usually used in sun-screens, tooth paste, and other daily used objects as a pigment. However, scientists have focused on titania as photocatalyst due to its excellent activities. By fabricating vanadium doped TiO2 and CuOx co-catalyzed TiO2 nano-size filter, the degradation level of the volatile organic compound (VOC) concentration was tested using 365nm UV LED as light source in a closed chamber. Main purpose for this test is to evaluate the activities of various catalysts for degrading the VOCs which are detrimental to human body and toluene and p-xylene were chosen in the VOC removal test. Target gas materials were injected into the test chamber with dry air as carrier gas which was flowed into the gas washer bottle filled with liquid form of VOC substance. When the VOC gas flows into the chamber, it is circulated by 200 mm fan in order to contact with the set-up filter on the aluminum holder. Target gas concentration in the chamber was monitored using VOC detector (miniRae3000, Raesystems) which was also placed inside the chamber. With the measured concentration, the VOC degradation efficiency and the degradation rate were evaluated and used to compare the catalytic activities.

• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.108-114
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• 2012

Salicylic acid degrades at different rates under UV-A light on $TiO_2$, ZnO, CuO, $Fe_2O_3$, $Fe_3O_4$ and $ZrO_2$ nanocrystals and all the oxides exhibit sustainable photocatalysis. While ZnO-photocatalysis displays Langmuir-Hinshelwood kinetics the others follow first order on [salicylic acid]. The degradation on all the oxides enhance with illumination intensity. Dissolved oxygen is essential for the photodegradation. ZnO is the most efficient photocatalyst to degrade salicylic acid. Besides serving as the effective photocatalyst to degrade salicylic acid it also acts as a bactericide and inactivates E.coli even in absence of direct light.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.146-146
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• 2011

The blue light emitting diode (LED) structure based on non-polar a-plane (11-20) GaN which was coated TiO2 nanoparticles using spin coating method was grown on r-plane (1-102) sapphire substrates to improve light extraction efficiency. We report on the emission and structural properties with temperature dependence of photoluminescence (PL) and x-ray rocking curves (XRC). From PL results at 13 K of undoped GaN samples, basal plane stacking fault (BSF) and near band edge (NBE) emission peak were observed at 3.434 eV and 3.484 eV, respectively. We also found the temperature-induced band-gap shrinkage, which was fitted well with empirical Varshini's equation. The PL intensity of TiO2 nanoparticles ?coated multiple quantum well (MQW) sample is decayed slower than that of no coating sample with increasing temperature. The anisotrophic strain and azimuth angle dependence in the films were shown from XRC results. The full width at half maximum (FWHM) along the GaN [11-20] and [1-100] directions were 564.9 arcsec and 490.8 arcsec, respectively. A small deviation of FWHM values at in-plane direction is attributed to uniform in-plane strain.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.53-58
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• 2017

In the age of oil exhaustion, low cost, semi-transparent solar cell, the dye-sensitized solar cell (DSC) has attracted significant attention since 1991 of $Gr{\ddot{a}}tzel$ report. To enhance the light-harvest capability of the photoelectric electrode, and efficiency of photoelectric transformation of the DSC, scattering layer of various structure have been proposed to photoelectric electrode materials. The scattering center of scattering layer needs the large titanium dioxide nanoparticles of 250 - 300 nm in diameter. In this study, the large sized $TiO_2$ nanocyrstals of around 300 nm were synthesized using the modified sol-gel process. According to the analysis of XRD and TEM, the synthesized $TiO_2$ nanoparticles exhibit single crystals of anatase phase. The optical transmittance of the synthesized titanium dioxide film prepared by spin coating is around 50% at 550 nm. It is suitable for scattering layer as a scattering center, and expected to enhance the efficiency of photoelectric transformation of the DSC.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4035-4040
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• 2011

Long $TiO_2$ nanotube (NT) arrays, prepared by electrochemical anodization of Ti foils, have been utilized as dye-adsorbing electrodes in dye-sensitized solar cells (DSCs). By anodizing for 1-24 hr and subsequent annealing, highly crystallized and tightly-adhered NT arrays were tailored to 11-150 ${\mu}m$ lengths, ~90 nm innerpore diameter and ~30 nm wall thickness. I-V curves revealed that the photovoltaic conversion efficiency (${\eta}$) was proportional to the NT length up to 36 ${\mu}m$. Beyond this length, the ) was proportional to the NT length up to ${\eta}$ was still steadily increased, though at a much lower rate. For example, an ${\eta}$ of 5.05% at 36 ${\mu}m$ was increased to 6.18% at 150 ${\mu}m$. Transient photoelectron spectroscopic analyses indicated that NT array-based DSCs revealed considerably higher electron diffusion coefficient ($D_e$) and life time (${\tau}_e$) than those with $TiO_2$ nanoparticles (NP). Moreover, the electron diffusion lengths ($L_e$) of the photo-injected electrons were considerably larger than the corresponding NT lengths in all the cases, suggesting that electron transport in NT arrays is highly efficient, regardless of tube length.

• International Journal of Computer Science & Network Security
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• v.22 no.6
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• pp.91-96
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• 2022

The photocatalytic degradation of salicylic acid takes place in several stages involving coupled phenomena, such as the transport of molecules and the chemical reaction. The systems of transport equations and the photocatalytic reaction are numerically solved using COMSOL Mutiphysics (CM) simulation software. CM will make it possible to couple the phenomena of flow, the transport of pollutants (salicylic acid) by convection and diffusion, and the chemical reaction to the catalytic area (bauxite or TiO2 doped by nanoparticles). The simulation of the conversion rate allows to correctly fit the experimental results. The temporal simulation shows that the reaction reaches equilibrium after a transitional stage lasting over one minute. The outcomes of the study highlight the importance of diffusion in the boundary layer and the usefulness of injecting micro-agitation into the microchannel flow. Under such conditions, salicylic acid degrades completely.