• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.1
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• pp.44-47
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• 2012

The $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ multi layered structure was designed for the possible application of transparent electrodes in PDP (Plasma Display Panel). Multi layered film was deposited on a glass substrate at room temperature by DC/RF magnetron sputtering system and EMP (Essential Macleod Program) was adopted to optimize the optical characteristics of film. During the deposition process, the Ag layer in $TiO_2/Ag/TiO_2$ became heavily oxidized and the filter characteristic was degraded easily. In thus study, Si3N4 layer was used as a diffusion buffer layer between $TiO_2$ and Ag. in order to prevent the oxidation of Ag layer in $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ structure. It was confirmed that $Si_3N_4$ layer is one of candidate materials acting as diffusin barrier between $TiO_2/Ag/TiO_2$.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.620-626
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• 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.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.3
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• pp.134-138
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• 2015

Ag intermediated $TiO_2$ films were deposited by RF and DC magnetron sputtering and then vacuum annealed at 100, 200 and $300^{\circ}C$ for 30 minutes to investigate the effect of annealing temperature on the structural and optical properties of the films. For all depositions, the thickness of the $TiO_2$ and Ag films were kept constant at 24 and 15 nm by controlling the deposition time. As-deposited $TiO_2/Ag/TiO_2$ trilayer films have a weak crystalline and an optical reflectance in a near infrared wavelength region of 77.8%, while the films annealed at $300^{\circ}C$ show the polycrystalline structure and an increased mean optical reflectance of 80.4%. From the experimental results, it can be concluded that increasing the annealing temperature enhanced the structural and optical properties of the $TiO_2/Ag/TiO_2$ films.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.489-496
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• 2015

In this study, novel $Ag_2Se$ sensitized $TiO_2$ nanocomposites were prepared by facile sonochemical assisted synthesis method. The as-prepared products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and N2 adsorption BET analysis. The as-prepared $Ag_2Se/TiO_2$ nanocomposites simultaneously possessed great adsorptivity for organic dyes and efficient charge separation properties. In the decolorization of rhodamine B, a significant enhancement in the reaction rate was observed for the $Ag_2Se/TiO_2$ nanocomposite compared to the cases of using pure P25 or $TiO_2$. The sonocatalysis activity was higher due to the greater formation of reactive radicals, as well as to the increase of the active surface area of the $Ag_2Se/TiO_2$ nanocomposite.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.389-393
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• 2008

Nano-sized $TiO_2$-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and $Sr(OH)_2\;{\cdot}\;8H_2O$ as precursors. 3, -5, -7 wt%Ag spot-coated $TiO_2$-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using $TiO_2$-60 wt% SrO composite powders calcined at $1050^{\circ}C$, which mainly exhibited the $SrTiO_3$phase. However, a small number of rutile $TiO_2$, $Sr_2TiO_4$ and $SrO_2$ phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the $TiO_2$-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated $TiO_2$-SrO and $TiO_2$-SrO composite powders for degradation of phenol showed that all of $TiO_2$-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated $TiO_2$-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did $TiO_2$-SrO composite powders under visible light.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.373-376
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• 2012

Thin films of Ag-SiO2-TiO2 composite oxides with SiO2/TiO2 of 20/80 molar compositions were prepared by the sol-gel method, using tetraethylorthosilicate (TEOS) and titanium isopropoxide (TIP) as precursors. Ag-SiO2-TiO2 films coated on commercial glass substrates have successfully been synthesized using sol-gel method. The Ag-SiO2-TiO2 film with 0.5% Ag-added concentration and 20 mol% SiO2-mixture gives optimal results on crystalline structure, optical property, surface area, and photochromic property. Absorption near the wavelength of the incident light decreased gradually. The reversibility of the two-photon writing process in Ag-SiO2-TiO2 film is clearly seen.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.535-539
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• 2002

In this study photoadsorption propreties of Ag ion in AgNO$_3$ solution by TiO$_2$nanopowder synthesized by homogeneous precipitation process at low temperature were investigated. It was found that the photocatalytic redliction in AgNO$_3$solution was occurred by TiO$_2$nanopowder even under th sun light irradiation, although the reduction of Ag ions was slow with th small adsorption of 9.32 ppm. Notably the Ag adsorption was promoted in th dark condition probably owing to the chestnut bur shape of TiO$_2$ nanopowder itself. In the application of UV the Ag ions were completely adsorbed within 120 min, showing more significant photocatalytic reaction. The measured adsorption reaction rate and adsorption equilibrium rate constants were 0.0004 g/min and 1494.20(120 $m^2$/g), respectively.

• Journal of the Korean GEO-environmental Society
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• v.20 no.11
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• pp.5-10
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• 2019

For the development of long-wavelength responding photocatalyst, Ag was applied to commercial $TiO_2$ to produce $Ag/TiO_2$ photocatalyst. Moreover, micro-emulsion method was used in order to increase the efficiency of the photocatalyst by enhancing the dispersion of Ag. Physical properties of the manufactured catalyst were analyzed by scanning electron microscopy (SEM), field emission transmission electron microscopy (FE-TEM) and diffuse reflectance spectroscopy (DRS). For the catalytic performance measurement, RO 16 (Reactive Orange 16) removal was performed with 25 ppm RO 16 under UV-A (365 nm) irradiation. In addition, ball milling and dip-coating method were used to synthesize the photocatalyst for the comparison of the outcomes of using different synthesis methods. In addition, catalytic performance was improved by varying the Ag content and surfactant content. The highest catalytic performance was shown at $Ag/TiO_2$ synthesized by micro-emulsion method with 2 wt% of Ag content, and 0.5 g of the surfactant.

• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.168-173
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• 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.