• Title, Summary, Keyword: Ag-doped $TiO_2$

Search Result 28, Processing Time 0.045 seconds

Photocatalytic Properties of the Ag-Doped TiO2 Prepared by Sol-Gel Process/Photodeposition (졸-겔공정/광증착법을 이용한 Ag-Doped TiO2 합성 및 광촉매 특성)

  • Kim, Byeong-Min;Kim, Jung-Sik
    • Korean Journal of Materials Research
    • /
    • v.26 no.2
    • /
    • pp.73-78
    • /
    • 2016
  • $TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

Enhanced Self-Cleaning Performance of Ag-F-Codoped TiO2/SiO2 Thin Films

  • Kim, Byeong-Min;Kim, Jung-Sik
    • Korean Journal of Materials Research
    • /
    • v.28 no.11
    • /
    • pp.620-626
    • /
    • 2018
  • Highly self-cleaning thin films of $TiO_2-SiO_2$ co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom $SiO_2$ and top $TiO_2$ layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of $Ag-F-TiO_2/SiO_2$ thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The $Ag-F-TiO_2/SiO_2$ thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure $TiO_2$, Ag-doped $TiO_2$, and F-doped $TiO_2$ films.

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

  • 윤기현;김태희
    • Journal of the Korean Ceramic Society
    • /
    • v.22 no.3
    • /
    • pp.19-24
    • /
    • 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.

  • PDF

Effects of Surface Characteristics of TiO2 Nanotublar Composite on Photocatalytic Activity (TiO2 복합 광촉매의 표면 특성과 광촉매 효율)

  • Lee, Jong-Ho;Youn, Jeong-Il;Kim, Young-Jig;Oh, Han-Jun
    • Korean Journal of Materials Research
    • /
    • v.24 no.10
    • /
    • pp.556-564
    • /
    • 2014
  • To synthesize a high-performance photocatalyst, N doped $TiO_2$ nanotubes deposited with Ag nanoparticles were synthesized, and surface characteristics, electrochemical behaviors, and photocatalytic activity were investigated. The $TiO_2$ nanotubular photocatalyst was fabricated by anodization; the Ag nanoparticles on the $TiO_2$ nanotubes were synthesized by a reduction reaction in $AgNO_3$ solution under UV irradiation. The XPS results of the N doped $TiO_2$ nanotubes showed that the incorporated nitrogen ions were located in interstitial sites of the $TiO_2$ crystal structure. The N doped titania nanotubes exhibited a high dye degradation rate, which is effectively attributable to the increase of visible light absorption due to interstitial nitrogen ions in the crystalline $TiO_2$ structure. Moreover, the precipitated Ag particles on the titania nanotubes led to a decrease in the rate of electron-hole recombination; the photocurrent of this electrode was higher than that of the pure titania electrode. From electrochemical and dye degradation results, the photocurrent and photocatalytic efficiency were found to have been significantly affected by N doping and the deposition of Ag particles.

Characteristics of TiO2 and Ag/TiO2 optical thin film by Co-sputtering method (동시 스퍼터링법에 이용하여 제작한 TiO2와 Ag/TiO2 광학 박막의 특성)

  • Kim, Sang-Cheol;Hahn, Sung-Hong;Kim, Eui-Jung;Lee, Chung-Woo;Joo, Jong-Hyun;Kim, Goo-Cheol
    • Korean Journal of Optics and Photonics
    • /
    • v.16 no.2
    • /
    • pp.168-173
    • /
    • 2005
  • Ag-doped $TiO_2$ thin films were prepared by RF magnetron co-sputtering method, and their physical and chemical properties were examined as a function of calcination temperature. XRD results showed that the crystallite size of Ag-doped films was smaller than that of the $TiO_2$ thin films. SEM results showed that the particle size of $Ag/TiO_2$ film was smaller and more uniform than pure $TiO_2$ film. The films had high transparency in the visible range. The films calcined at $600^{\circ}C$ were the anatase phase, and the films calcined at $900^{\circ}C$ were a mixture of anatase and rutile phases. The absorption edge of films calcined at $900^{\circ}C$ was red-shifted. This is due to the augmented absorption resulting from the phase transformation from anatase to rutile phase. And the transmittance of films decreased by the light scattering and absorption in the films. Photocatalytic activity of $Ag/TiO_2$ thin films was higher than that of the pure $TiO_2$ thin films.

The Syntheses, Characterizations, and Photocatalytic Activities of Silver, Platinum, and Gold Doped TiO2 Nanoparticles

  • Loganathan, Kumaresan;Bommusamy, Palanisamy;Muthaiahpillai, Palanichamy;Velayutham, Murugesan
    • Environmental Engineering Research
    • /
    • v.16 no.2
    • /
    • pp.81-90
    • /
    • 2011
  • Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

Combination of Light Emitting Diode at 375 nm and Photo-reactive TiO2 Layer Prepared by Electrostatic Spraying for Sterilization

  • Hwang, Kyu-Seog;Jeon, Young-Sun;Choi, Tae-Il;Hwangbo, Seung
    • Journal of Electrical Engineering and Technology
    • /
    • v.8 no.5
    • /
    • pp.1169-1174
    • /
    • 2013
  • The objective of this work was to increase the efficiency of ultraviolet-light emitting diodes at 375 nm for sterilization. Since $TiO_2$ had antibacterial properties, which were attributed to the appearance of hydroxyl radicals and superoxide radical anions on the surface species under ultra violet radiation at about 387 nm, photo-reactive layers such as Ag-doped $TiO_2$ were coated on aluminum substrates by electrostatic spraying. Crystallinity and surface morphology of the coating layer were examined by X-ray diffraction ${\theta}-2{\theta}$ scan and field emission-scanning electron microscope, respectively. In an antibacterial test, we observed above 99% reduction of Escherichia coli populations on 3 or 5 mol% Ag-doped $TiO_2$ layers after irradiation for 2 hrs at 375 nm, while very low inactivation on bare aluminum substrates occurred after irradiation as the same condition.

Impedance spectroscopy analysis of the $Li_2CO3$ doped $(Ba,Sr)TiO_3$ thick films

  • Ham, Yong-Su;Go, Jung-Hyeok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.27-28
    • /
    • 2009
  • In this study, we have fabricated the 3 wt% $Li_2CO3$ doped $(Ba,Sr)TiO_3$ thick films on the Ag/Pd printed $Al_2O_3$ substrates for the LTCCs (Low Temperature Co-fired Ceramics) applications. From the X-ray diffraion analysis, 3 wt% $Li_2CO3$ doped BST thick films on the Ag/Pd printed $Al_2O_3$ substrates, which sintered at 900 $^{\circ}C$ have perovskite structure without any pyro phase. The dielectric properties of 3 wt% $Li_2CO3$ doped BST thick films were measured from 1 kHz to 1 MHz. To investigate the electrical properties of 3 wt% $Li_2CO3$ doped BST thick films, we employed the impedance spectroscopy. The complex impedance of 3 wt% $Li_2CO3$ doped BST thick films were measured from 20 Hz to 1 MHz at the various temperatures.

  • PDF

AC & DC Electrical Characterization of PTC $BaTiO_3$ and Electrodes (PTC $BaTiO_3$ 및 전극의 직류 및 교류 특성)

  • 전표용;최경만
    • Journal of the Korean Ceramic Society
    • /
    • v.28 no.2
    • /
    • pp.101-108
    • /
    • 1991
  • 0.2 mo1% La doped BaTiO3 samples were prepared by a wet chemical process (Pechini process) and electrical conductivity were measured from annealing temperatures(800-110$0^{\circ}C$) to room temperature continuously. 2 probe I-V characteristics showed that Pt electrodes were non-ohmic below about 80$0^{\circ}C$ for Ladoped sample. I-V curves showed varistor behavior and breakdown voltages showed PTC-like behavior. AC complex impedance of 0.2 La and 0.05 Mn mo1% doped BaTiO3 samples with three different electrodes (electroless Ni, Pt, Ag electrodes) were measured with temperature variation. Complex impedance plots showed that the samples with electroless Ni electrodes have negligible electrode resistance. Samples with Ag or Pt paste electrodes showed large electrode resistance. PTC effect, which is defined as the ratio of maximum resistance to minimum resistance, was found to be less than 10 for 0.2 mo1% La doped dense sample however greater than 105 with codoping of 0.05 mo1% Mn and 0.2 mol% La.

  • PDF