$TiO_2$-Encapsulated EFAL-Removed Zeolite Y as a New Photocatalyst for Photodegradation of Azo Dyes in Aqueous Solution

조원재,윤숙자,윤민중,ChO, Won-Je,Sook-Ja Yoon,,Yoon, Min-Joong 한국광과학회 2005 Journal of Photosciences Vol.12 No.1

Application of a new photocatalyst has been attempted to improve the efficiency and rates of photocatalytic degradation of azo dyes by using a model dye such as Methyl Orange. As a new photocatalyst, $TiO_2$ encapsulated EFAL-removed zeolite Y ($TiO_2$ /EFAL-removed zeolite Y) has been synthesized by ion-exchange in the mixture of EFAL-removed zeolite Y with 0.05 M aqueous [$(NH_4)_2 TiO(C_2O_4)_2.H_2O$] [$TiO(C_2O_4)_2.H_2O$]. This new photocatalyst has been characterized by measuring XRD, IR and reflectance absorption spectra as well as ICP analysis, and it was found that the framework structure of $TiO_2$ /EFAL-removed zeolite Y is not changed by removing the extra-framework aluminum (EFAL) from the normal zeolite Y and the $TiO_2$ inside the photocatalyst exists in the form of $(TiO^{2+})_n$ nanoclusters. Based on the ICP analysis, the Si/Al ratio of the $TiO_2$ /EFAL-removed zeolite Y and the weight of $TiO_2$ were determined to be 23 and 0.061g in 1.0g photocatalyst, respectively. It was also found that adsorption of the azo dye in the $TiO_2$ /EFAL-removed zeolite is very effective (about 80 % of the substrate used). This efficient adsorption contributes to the synergistic photocatalytic activities of the $TiO_2$ /EFAL-removed zeolite by minimizing the required flux diffusion of the substrate. Thus, the photocatalytic reduction of methyl orange (MO) was found to be 8 times more effective in the presence of $TiO_2$ /EFAL-removed zeolite Y than in the presence of $TiO_2$ /normal zeolite Y. Furthermore, the photocatalytic reduction of MO by using 1.0 g of the $TiO_2$ /EFAL-removed zeolite Y containing 0.061g of $TiO_2$ is much faster than that carried out by using 1.0 g of Degussa P-25.

TiO_{2-x}N_x의 저온제조 및 광화학적 특성

정동운,Jung, Dong-Woon 대한화학회 2010 대한화학회지 Vol.54 No.1

용액침전법에 의해 $TiO_2$ 및 $TiO_{2-x}N_x$를 제조하였다. $TiO_{2-x}N_x$ 시료는 순수한 $TiO_2$의 띠 간격인 3.20 eV (390 nm 흡광)로부터 1.77 eV (700 nm 흡광)까지 띠 간격이 줄어들게 되어 자외선 영역 뿐 아니라 가시광선 전체 영역에서도 흡광이 발생하였다. 가시광선에서의 광촉매 활성에서도 $TiO_{2-x}N_x$ 시료는 순수한 $TiO_2$ 및 P-25보다도 더 높은 활성도를 나타냈다. $TiO_2$ and N-substituted $TiO_{2-x}N_x$ were synthesized by using precipitation method. $TiO_{2-x}N_x$ compound absorbed whole UV light as well as long wavelength of visible light (400 - 700 nm) because of the change of band gap from 3.2 eV to 1.77 eV. Results obtained revealed that $TiO_{2-x}N_x$ showed higher activity than pure $TiO_2$ or P-25 for visible-photocatalytic degradation of 1,4-dichlorobenzene.

Yb³⁺ Er³⁺ ions 동시도핑에 의한 TiO₂ 분말의 열적 안정성 증가효과와 upconversion 특성 연구

은종원,오동근,김광진,홍태의,정성민,최봉근,심광보,Eun, Jong-Won,Oh, Dong-Keun,Kim, Kwang-Jin,Hong, Tae-Ui,Jeong, Seong-Min,Choi, Bong-Geun,Shim, Kwang-Bo 한국결정성장학회 2010 韓國結晶成長學會誌 Vol.20 No.4

Sol-gel method로 합성한 anatase상의 $TiO_2$와 Yb와 Er을 codoping한 $TiO_2:Yb^{3+},\;Er^{3+}$ 파우더의 열적안정성과 이에 따른 광촉매 특성의 변화를 비교하였다. XRD 분석을 통하여 $TiO_2$ 결정성 및 상변화에 $Yb^{3+},\;Er^{3+}$ ions이 미치는 영향을 온도에 따라 비교하였으며 anatase $TiO_2$와 rutile $TiO_2$의 광학적 성질을 UV-Vis을 통하여 비교하였다. UV-Vis 분석결과 anatase $TiO_2:Yb^{3+},\;Er^{3+}$ ions도핑에 의하여 $TiO_2$의 밴드갭이 미세하게 감소함을 확인하였고 이를 통해 광촉매 작용을 향상시킬 수 있음을 확인하였다. $Yb^{3+}$ 이온과 $Er^{3+}$ 이온이 도핑된 $TiO_2:Yb^{3+},\;Er^{3+}$ 파우더를 980 nm에서 PL 분석하여 녹색 및 적색 형광을 하는 up-converting 형광특성을 분석하였다. Thermal stabilizing effect of $Yb^{3+},\;Er^{3+}$ codoping into $TiO_2$ powder prepared by sol-gel method and its upconversion characteristics were analyzed. The effect of $TiO_2:Yb^{3+},\;Er^{3+}$ ions on crystallinity and phase transition was studied by X-ray diffraction (XRD). The change of band-gap energy induced from Yb and Er codoping was analyzed by UV-Vis. The band-gap energy of $TiO_2$ have been slightly narrowed by $Yb^{3+},\;Er^{3+}$ codoping, which indicated that the $Yb^{3+},\;Er^{3+}$ ions can enhance the photo-catalytic property of $TiO_2$. green and red up-conversions of $Yb^{3+}$ and $Er^{3+}$ co-doped $Y_2O_3:Yb^{3+},\;Er^{3+}$ phosphor were analyzed by PL equipped with 980 nm laser.

HAP/TiO<SUB>2</SUB> 여재를 이용한 Reactive Black 5(RB5)의 광촉매 반응과 흡착

천석영(Chun. Sukyoung),장순웅(Chang, Soonwoong) 한국지반환경공학회 2011 한국지반환경공학회논문집 Vol.12 No.11

본 연구는 Hydroxyapatite(HAP)/TiO2 여재에 의한 Reactive Black 5(RB5)의 흡착과 광촉매 반응을 조사하였다. RB5에 대한 TiO2, HAP와 TiO2/HAP의 흡착은 연속적인 회분식 실험을 통해 조사하였다. 흡착평형에 따른 결과를 나타내었으며 Langmuir와 Freundlich isotherm model을 사용하여 적용성을 조사하였다. TiO2, HAP와 TiO2/HAP 흡착제별 흡착평형 결과는 Langmuir isotherm model에 적합하였으며 최대흡착량(Qmax)의 값은 각각 단일 TiO2는 5.28mg/g, 단일 HAP는 12.45mg/g, TiO2/HAP는 9.03mg/g으로 나타났다. 흡착과 광촉매 반응에 대한 kinetic model들은 유사 1차 반응을 통해 분석하였으며, 이들 model에 따르면 TiO2/HAP에 의한 RB5 제거는 광촉매 반응과 흡착반응의 상호작용의 영향을 받는 것으로 나타났다. This study investigated on the adsorption and photocatalysis of Reactive Black 5(RB5) by the hydroxyapatite(HAP)/ Titanium dioxide(TiO2) media. The adsorption of RB5 on TiO2, HAP and TiO2/HAP was investigated during a series of batch adsorption experiments. The amounts adsorbed at equilibrium were measured. Langmuir and Freundlich isotherm models were tested for their applicability. The result of equilibrium studies of TiO2, HAP and TiO2/HAP adsorbent were found to follow Langmuir isotherm model. The adsorbed amounts(Qmax) were found to be 5.28mg/g on single TiO2, 12.45mg/g on single HAP and 9.03mg/g on TiO2/HAP, respectively. The experimental data were analysed using the pseudo-first-order adsorption and photocatalysis kinetic models. According to these models, RB5 degradation by TiO2/HAP was affected by interaction effect of photocatalysis and adsorption.

원자층 증착장치에 의한 TiO2 박막 코팅된 폴리머 절연체의 표면 및 전기적 특성의 향상

박용섭,김남훈 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.7

Titanium oxide (TiO2) thin films were synthesized on polymer insulator and Si substrates by atomic layer deposition (ALD) method. The surface and electrical properties of TiO2 films synthesized at various ALD cycle numbers were investigated. The synthesized TiO2 films exhibited higher contact angle and smooth surface. The contact angle of TiO2 films was increased with the increase of ALD-cycle number. Also, the rms surface roughness of films was slightly rough with the increase of ALD-cycle number. The leakage current on TiO2 film surface synthesized at various conditions were uniformed, and the values were decreased with the increase of ALD-cycle number. In the results, the performance of TiO2 films for self-cleaning critically depended on a number of ALD-cycle. TiO2 박막은 원자층 증착 장치(ALD)를 이용하여 폴리머 절연체와 실리콘 기판위에 합성하였다. 다양한 ALD 사이클 수에 따라 제작되어진 TiO2 박막의 표면과 전기적 특성이 고찰되었다. 합성되어진 TiO2 박막은 높은 접촉각과 부드러운 표면을 나타내었다. 도한 TiO2 박막의 접촉각은 ALD 사이클 수가 증가함에 따라 증가하였다. 박막의 rms 표면 거칠기 값은 ALD 사이클 수의 증가에 따라 약간 거칠어 졌다. 다양한 조건에서 합성되어진 TiO2 박막 표면에서 누설전류 값은 균일하였고, 이 값은 ALD 사이클 수의 증가에 따라 감소하였다. 결과로서 자기세정 응용을 위한 TiO2 박막의 특성들은 ALD 사이클 수에 의존하는 것을 확인하였다.

TiO₂/Carbon Composites Prepared from Rice Husk and the Removal of Bisphenol A in Photocatalytic Liquid System

Kim, Ji-Yeon,Kwak, Byeong-Sub,Kang, Mi-Sook Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

The improved photocatalytic performance of a carbon/$TiO_2$ composite was studied for the Bisphenol A (BPA) decomposition. Titanium tetraisopropoxide (TTIP) and a rice husk from Korea were heterogeneously mixed as the titanium and carbon sources, respectively, for 3 h at room temperature, and then thermally treated at $600^{\circ}C$ for 1 h in $H_2$ gas. The transmission electron microscopy (TEM) images revealed that the bulk carbon partially covered the $TiO_2$ particles, and the amount that was covered increased with the addition of the rice husk. The acquired carbon/$TiO_2$ composite exhibited an anatase structure and a novel peak at $2{\theta}=32^{\circ}$, which was assigned to bulk carbon. The specific surface area was significantly enhanced to 123~164 $m^2/g$ in the carbon/$TiO_2$ composite, compared to $32.43m^2/g$ for the pure $TiO_2$. The X-ray photoelectron spectroscopy (XPS) results showed that the Ti-O bond was weaker in the carbon/$TiO_2$ composite than in the pure $TiO_2$, resulting in an easier electron transition from the Ti valence band to the conduction band. The carbon/$TiO_2$ composite absorbed over the whole UV-visible range, whereas the absorption band in the pure$TiO_2$ was only observed in the UV range. These results agreed well with an electrostatic force microscopy (EFM) study that showed that the electrons were rapidly transferred to the surface of the carbon/$TiO_2$ composite compared to the pure $TiO_2$. The photocatalytic performance of the BPA removal was optimized at a Ti:C ratio of 9.5:0.5, and this photocatalytic composite completely decomposed 10.0 ppm BPA after 210 min, whereas the pure $TiO_2$ achieved no more than 50% decomposition under any conditions.

TiO₂ Interlayer의 상변화에 따른 PLZT 박막의 구조 및 전기적 특성

이철수,윤지언,황동현,차원효,손영국,Lee, Chul-Su,Yoon, Ji-Eon,Hwang, Dong-Hyun,Cha, Won-Hyo,Sona, Young-Gook 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.6

R.F. magnetron-sputtering 방법에 의해 $(Pb_{1.1},La_{0.08})(Zr_{0.65}.Ti_{0.35})O_3$ 박막을 $Pt/Ti/SiO_2/Si$, $TiO_2(interlayer)/Pt/Ti/SiO_2/Si$ 기판에 증착하고, $TiO_2$ interlayer에 의한 PLZT 박막의 특성을 고찰 하였다. $TiO_2$ interlayer의 증착조건을 변화시켜가며 단일상의 anatase 상과 rutile 상을 증착하였고, 그 위에 증착시킨 PLZT 박막의결정성을 x-ray diffraction(XRD)을 통해 분석하였다. 또한 $TiO_2$ interlayer에 의한 $PLZT-TiO_2$, $TiO_2-Pt$ 박막의 계면상태를 고찰하기 위해 glow discharge spectrometer(GDS) 분석을 행하였고, PLZT의 강유전 특성을 고찰하기 위해 전기적 측정을 행하였다. $TiO_2$ anatase 단일 상에 증착한 PLZT의 경우 (110) 방향으로 우선 배향됨을 알 수 있었고, 12.6 ${\mu}C/cm^2$의 잔류분극 값을 나타내었다. [ $(Pb_{1.1},La_{0.08})(Zr_{0.65}.Ti_{0.35})O_3$ ] thin films on the $Pt/Ti/SiO_2/Si$, $TiO_2(interlayer)/Pt/Ti/SiO_2/Si$ substrate were fabricated by the R.F. magnetron-sputtering method and considered their characteristics depending on $TiO_2$ interlayer. Changing the deposition conditions of $TiO_2$ interlayer, we obtained $TiO_2$ anatase single phase and rutile single phase. PLZT was deposited on these substrates and analyzed by x-ray diffraction(XRD) for there crystallinity and orientation. To investigate $PLZT-TiO_2$, $TiO_2-Pt$ interface, glow discharge spectrometer(GDS) analysis was carried out and we performed electrical measurements for dielectric properties of PLZT thin films. The PLZT thin film on $TiO_2$ anatase interlayer was found to have (110)-preferred orientation and 12.6 ${\mu}C/cm^2$ remaining polarization value.

Insertion of a TiO2 Buffer Layer for the Fixation of Electrospun TiO2 Nanofibers on Glass Substrates

Deuk Yong Lee,조정은,이명현,조남인,Yo-Seung Song 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1

Titania nanofibers were fabricated by drying electrospun TiO2/polyvinylpyrrolidone nanofibers for 5 h in air and subsequent annealing for 3 h at temperatures from 450℃ to 550℃ in air. To improve the bond strength, a TiO2buffer layer with a thickness of 400 nm was spin-coated onto the glass slide prior to electrospinning by using the same precursor solution. Only the anatase TiO2 phase was observed for the TiO2/PVP fibers calcined at temperatures between 450 and 550℃, but the fibers calcined at temperatures higher than 600℃ yielded a mixture of anatase and rutile phases. The bond strength of the TiO2 nanofibers with a height of 1 μm was investigated by using a tape test according to ASTM D 3359-02 to evaluate the extent of adhesion of the fiber mat to the glass substrate. Among the coatings, the highest bond strength of the fibers was achieved for the TiO2 nanofiber/TiO2 buffer layer/glass coatings calcined at 500℃. Experimental results revealed that the extent of adherence increased by 10% when the buffer layer was inserted between the fibers and the glass. Therefore, it can be concluded that the addition of a buffer layer has a modest influence on the bond strength between the nanofiber mat and the glass substrate. Titania nanofibers were fabricated by drying electrospun TiO2/polyvinylpyrrolidone nanofibers for 5 h in air and subsequent annealing for 3 h at temperatures from 450℃ to 550℃ in air. To improve the bond strength, a TiO2buffer layer with a thickness of 400 nm was spin-coated onto the glass slide prior to electrospinning by using the same precursor solution. Only the anatase TiO2 phase was observed for the TiO2/PVP fibers calcined at temperatures between 450 and 550℃, but the fibers calcined at temperatures higher than 600℃ yielded a mixture of anatase and rutile phases. The bond strength of the TiO2 nanofibers with a height of 1 μm was investigated by using a tape test according to ASTM D 3359-02 to evaluate the extent of adhesion of the fiber mat to the glass substrate. Among the coatings, the highest bond strength of the fibers was achieved for the TiO2 nanofiber/TiO2 buffer layer/glass coatings calcined at 500℃. Experimental results revealed that the extent of adherence increased by 10% when the buffer layer was inserted between the fibers and the glass. Therefore, it can be concluded that the addition of a buffer layer has a modest influence on the bond strength between the nanofiber mat and the glass substrate.

A Study on the Phase Composition, Microstructure and Photocatalytic Activity of Plasma Sprayed Titanium Oxide Coatings

Chang-Suk Han(Chang-Suk Han),Chan-Woo Lee(Chan-Woo Lee) 호서대학교 공업기술연구소 2022 공업기술연구 논문집 Vol.41 No.2

플라즈마 스프레이 방법을 이용하여 TiO2-FeTiO3 코팅의 광촉매 활성에 대한 FeTiO3의 영향을 조사하기 위해서 본 연구에서는 TiO2, FeTiO3 및 TiO2-FeTiO3 분말을 제작하였다. 플라즈마 스프레이 방법을 이용한 FeTiO3, TiO2-30%FeTiO3 및TiO2-50%FeTiO3 코팅막의 상 조성, 미세구조 및 광촉매 활성에 대하여 상세한 논의를 진행하였다. TiO2의 가시광선 반응성을 개선하기 위하여 2.85 eV의 밴드 갭을 갖는 FeTiO3를 TiO2 분말에 첨가하여 플라즈마 스프레이 방법으로 높은 광촉매 코팅을 시도하였다. 플라즈마 스프레이 방법으로 FeTiO3, TiO2-30%FeTiO3 및 TiO2-50%FeTiO3 코팅막의 조성과 광촉매 활성에 대하여 조사하였다. TiO2-FeTiO3 코팅막에서 전하 캐리어 분리 및 재조합에 대한 FeTiO3 화합물의 영향에 대하여 검토하였다. 400A의 아크전류로 분사된 FeTiO3 코팅 플라즈마는 금홍석 TiO2, FeTiO3, Fe2TiO5 및 열적으로 준 안정적인 Fe2Ti3O9 및 γ-Fe2O3로 구성되어 있었다. 아나타제 TiO2, 금홍석 TiO2 및 FeTiO3를 포함하는 400A의 아크전류로 분사된 TiO2-30%FeTiO3 코팅막은 코팅이 불리한 Fe2TiO5 상을 포함하지 않았기 때문에 우수한 광촉매 특성을 나타내었다.이 특성을 FeTiO3와 TiO2의 두 물질에 대한 가전자대 가장자리 수준과 밴드갭에 따라 설명하기 위해 2단계 전자 전달모델을 제안하였다. To elucidate the influence of FeTiO3 on the photocatalytic activity of plasma sprayed TiO2-FeTiO3 coatings, TiO2, FeTiO3 and TiO2-FeTiO3 powders were designed in this study. The phase composition, microstructure and photocatalytic activity of plasma sprayed FeTiO3, TiO2-30%FeTiO3 and TiO2-50%FeTiO3 coatings were discussed in detail. To improve the visible light responsibility of TiO2, FeTiO3 with band gap of 2.85 eV was added into TiO2 powder to fabricate high photocatalytic coating by plasma spraying technique. The compositions and photocatalytic activity of plasma sprayed FeTiO3, TiO2-30%FeTiO3 and TiO2-50%FeTiO3 coatings were investigated. The influence of FeTiO3 compound on the charge carrier separation and recombination in the TiO2-FeTiO3 coating was discussed. The FeTiO3 coating plasma sprayed under the arc current of 400 A consisted of rutile TiO2, FeTiO3, Fe2TiO5, and thermally metastable Fe2Ti3O9 and γ-Fe2O3. TiO2-30%FeTiO3 coating sprayed under the arc current of 400 A, which contained anatase TiO2, rutile TiO2 and FeTiO3, had good photocatalytic character because the coating did not contain the unfavorable Fe2TiO5 phase. A two-steps electron transfer model was proposed to explain this character according to the level of valence band edge and band gap of the two substances of FeTiO3 and TiO2.

Fabrication of dye-sensitized solar cells using a both-ends-opened TiO2 nanotube/nanoparticle hetero-nanostructure

Md Ashraf Hossain,오세현,임상우 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.51 No.-

We fabricated a hetero-structure photoanode with both-ends-opened TiO2 nanotubes and TiO2nanoparticles for dye-sensitized solar cells (DSSCs). Two-step anodization and selective etching processwere used to obtain the both-ends-opened TiO2 nanotubes. A heat treatment was employed to obtainanatase crystal-structured nanotubes. The effect of the both-ends-opened TiO2 nanotubes on thephotoelectric conversion efficiency (PCE) of the DSSCs was evaluated by positioning the TiO2 nanotubeson TiO2 nanoparticle layers and by sandwiching them between the TiO2 nanoparticles. It is suggested thatboth-ends-opened TiO2 nanotubes serve as incident light scattering layers that lead to superior lightharvesting efficiency of DSSCs. This increases the electron lifetime and results in the recycling of morelight by dye molecules, thus increasing the photocurrent density. Consequently, a high PCE of 7.74% wasobtained when the TiO2 nanotubes were placed on the TiO2 nanoparticles and a PCE of 8.56% wasobtained when the TiO2 nanotubes were placed between the TiO2 nanoparticles.