• Title/Summary/Keyword: anodic $TiO_2$

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Photoelectrochemical Converision with $SrTiO_3$ Ceramic Electrodes ($SrTiO_3$ 세라믹 전극에 의한 광전기 화학변환)

  • 윤기현;김태희
    • Journal of the Korean Ceramic Society
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    • v.22 no.3
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    • pp.19-24
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    • 1985
  • The phtoelectrochemical porperties of $Nb_2O_5$, $Sb_2O_3$ and $V_2O_5$ doped and pure $SrTiO_3$ ceramic electodes were investigated. Shapes of I-V and I-λ characteristics of the pure $SrTiO_3$ ceramic electrode are similar to those of SrTiO3 single crystal electorde ; the anodic current strats at -0.9V (vs. Ag/AgCI) in 1 N-NaOH aqueous solution and the photoresponse appears at a wavelength of about 390nm and the quantum efficiency is about 3.5% at wavelength of 390nm under 0.5V vs. Ag/AgCl. Photocurrents of $Nb_2O_5$, $Sb_2O_3$ and $V_2O_5$ doped electrodes and $V_2O_5$ doped ceramic electrode appears at wavelength of 390nm and 500nm respectively.

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Growth Behaviors of Anodic Titanium Oxide Nanotubes in the Ethylene Glycol Solution According to Water Contents (에틸렌 글리콜 용액에서 물 함량에 따른 티타늄 양극산화 나노튜브의 성장거동)

  • Lee, Byunggwan;Lee, Seongeun;Choi, Jinwook;Jeong, Yongsoo;Oh, Han-Jun;Lee, Oh Yeon;Chi, Choong-Soo
    • Korean Journal of Metals and Materials
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    • v.46 no.11
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    • pp.730-736
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    • 2008
  • $TiO_2$ nanotubes fabricated in aqueous HF-based electrolytes have been generally grown only to about 500nm in length because of the strong dissolubility of HF acid. In this paper, ethylene glycol solution has been applied for increasing the length of the anodic $TiO_2$ nanotubes, and the growth behaviors of the nanotubes according to water contents has been investigated. Anodization of Ti in ethylene glycol + 1 wt% $NH_4F$ (EG solution) with water additions up to 10 wt% were carried out at the constant voltage of 20 V. The results show that a thin titanium oxide layer is formed in the initial stage and the nanotube structure grows underneath the initial layer. And the length of $TiO_2$ nanotubes decreases with the increasing water content in the solution. It can be ascribed to the locally acidified circumstance around the barrier layer inside the nanopore due to $H^+$ ion originated from water. The XPS for the nanotubes suggests that the spectra of Ti2p and O1s are the major chemical bonding states of the $TiO_2$, and those for F1s, N1s and C1s come from the compound of $(NH_4)_2TiF_6$.

Comparison of Photoelectrode Properties Between $TiO_2$ Thin films Doped with Tantalum and Dispersed with Nanosize Gold (탄탈륨 도핑 및 나노사이즈의 금입자분산된 $TiO_2$ 박막에서의 광전극 특성 비교)

  • Yoon, Jong-Won;Jung, Kyung-Han;Koshizaki, Naoto;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.861-864
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    • 2004
  • 본 연구에서는 Ta이 도핑된 $TiO_2$$Au/TiO_2$ nanocomposite 박막을 co-sputtering법으로 제작하였다. Ta-doped $TiO_2$ 박막은 금흥석(rutile)에서 아나타제 상으로 변하는 구조를 유도하는 고용체를 형성했다. $Au/TiO_2$ nanocomposite film의 경우에는, 지름이 약 15 nm인 Au particles들이 $TiO_2$ matrix에 균질하게 분포되었다. Ta가 도핑된 $TiO_2$ 전극과 $Au/TiO_2$ 나노 콤포사이트 전극의 anodic photocurrents가 UV뿐만 아니라 가시광선 영역에서도 관찰되었다. Ta이 도핑된 $TiO_2$ 전극과 $Au/TiO_2$ 나노 콤포사이트 사이의 가시광선 영역에서 photoresponse는 계면 상태로 부터의 bandgap의 감소와 전자의 photoexcitation 때문이다.

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Simultaneous Detection of Tartrazine-Sunset Yellow in Food Samples Using Bioxide/Carbon Paste Microcomposite with Lanthanum and Titanium

  • Nagles, Edgar;Ceroni, Mario;Hurtado, John
    • Journal of Electrochemical Science and Technology
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    • v.11 no.4
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    • pp.421-429
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    • 2020
  • This report describes the simultaneous detection of the two dyes most commonly used in food, tartrazine (TZ) and sunset yellow (SY), based on a microcomposite of carbon paste decorated with La2O3 and TiO2. Anodic currents for SY-TZ were observed at 0.89-1.21 V by cyclic voltammetry (CV) separated with a ΔV of 0.32 V. The increased anodic peak currents compared to that of the unmodified carbon paste electrode were almost 50 and 41% for SY-TZ, respectively. The detection limits with the optimal amount of La2O3-TiO2 were 0.02 and 0.03 µmol/L, respectively. The relative standard deviation (RSD) based on fifty measurements was less than 3%. The versatility and novelty of the sensor were tested with food samples containing these substances and other substances.

Preparation of Ta-doped $TiO_2$ thin rums by co-sputtering and their photo-electrode properties (동시스퍼터법에 의한 Ta 도핑된 $TiO_2$ 박박 합성과 광전극 특성)

  • Yoon, Jong-Won
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.4
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    • pp.165-168
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    • 2008
  • Ta-doped thin films were deposited on quartz and indium-tin oxide glass substrates using a co-sputtering method. The Ta-doped films formed a solid solution that induced structural changes from rutile to anatase phase. The anodic photocurrents of the Ta-doped $TiO_2$ electrodes were observed not only in UV but also in the visible light range. The photocurrent response in visible light on Ta-doped $TiO_2$ films are due to bandgap reduction.

Morphological Studies on TiO2 Nanotubes Formed by Anodizing in Aqueous and Non-Aqueous Solutions (수용액 및 비수용액에서 양극산화법으로 형성된 TiO2 나노튜브의 구조 연구)

  • Kim, Byung-Jo;Moon, Sung-Mo;Jeong, Yong-Soo;Kim, Byung-Kwan
    • Journal of the Korean institute of surface engineering
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    • v.43 no.4
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    • pp.180-186
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    • 2010
  • $TiO_2$ nanotubes were formed on Ti by anodizing in 1 M $H_3PO_4$ + 0.3 M HF and 0.1 M $NH_4F$ + 2% $H_2O$ in ethylene glycol, and their surface and cross-sectional morphologies were observed using FE-SEM as a function of anodizing time and applied voltage. The cross-section of the $TiO_2$ nanotubes was readily observed from the small pieces of nanotubes remaining near the scratch lines after scratching of the anodized surface. $TiO_2$ nanotubes was observed to grow faster and thicker in non-aqueous solution than in aqueous solution. Diameter of $TiO_2$ nanotubes was proportional to the applied voltage, irrespective of the type of the electrolyte, and it is recommended to use non-aqueous solutions for the preparation of larger diameter of $TiO_2$ nanotubes.

Effects of Anodic Voltages of Photcatalytic TiO2 and Doping in H2SO4 Solutions on the Photocatalytic Activity (광촉매 TiO2의 황산용액에서의 양극산화전압과 도핑이 광촉매 활성에 미치는 영향)

  • Lee, Seung-Hyun;Oh, Han-Jun;Chi, Choong-Soo
    • Korean Journal of Materials Research
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    • v.22 no.8
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    • pp.439-444
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    • 2012
  • To compare the photocatalytic performances of titania for purification of waste water according to applied voltages and doping, $TiO_2$ films were prepared in a 1.0 M $H_2SO_4$ solution containing $NH_4F$ at different anodic voltages. Chemical bonding states of F-N-codoped $TiO_2$ were analyzed using surface X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the co-doped $TiO_2$ films was analyzed by the degradation of aniline blue solution. Nanotubes were formed with thicknesses of 200-300 nm for the films anodized at 30 V, but porous morphology was generated with pores of 1-2 ${\mu}m$ for the $TiO_2$ anodized at 180 V. The phenomenon of spark discharge was initiated at about 98 V due to the breakdown of the oxide films in both solutions. XPS analysis revealed the spectra of F1s at 684.3 eV and N1s at 399.8 eV for the $TiO_2$ anodized in the $H_2SO_4-NH_4F$ solution at 180 V, suggesting the incorporation of F and N species during anodization. Dye removal rates for the pure $TiO_2$ anodized at 30 V and 180 V were found to be 14.0% and 38.9%, respectively, in the photocatalytic degradation test of the aniline blue solution for 200 min irradiation; the rates for the F-N-codoped $TiO_2$ anodized at 30 V and 180 V were found to be 21.2% and 65.6%, respectively. From the results of diffuse reflectance absorption spectroscopy (DRS), it was found that the absorption edge of the F-N-codoped $TiO_2$ films shifted toward the visible light region up to 412 nm, indicating that the photocatalytic activity of $TiO_2$ is improved by appropriate doping of F and N by the addition of $NH_4F$.