• Title/Summary/Keyword: photocatalytic properties

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Synthesis and Photocatalytic Properties of Thermally Stable Metal-Oxide Hybrid Nanocatalyst with Ultrathin Oxide Encapsulation

  • Naik, Brundabana;Moon, Song Yi;Kim, Sun Mi;Jung, Chan Ho;Park, Jeong Young
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.317.2-317.2
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    • 2013

  • Ultrathin oxide encapsulated metal-oxide hybrid nanocatalysts have been fabricated by a soft chemical and facile route. First, SiO2 nanoparticles of 25~30 nm size have been synthesized by modified Stobber's method followed by amine functionalization. Metal nanoparticles (Ru, Rh, Pt) capped with polymer/citrate have been deposited on functionalized SiO2 and finally an ultrathin layer of TiO2 coated on surface which prevents sintering and provides high thermal stability while maximizing the metal-oxide interface for higher catalytic activity. TEM studies confirmed that 2.5 nm sized metal nanoparticles are well dispersed and distributed throughout the surface of 25 nm SiO2 nanoparticles with a 3-4 nm TiO2 ultrathin layer. The metal nanoparticles are still well exposed to outer surface, being enabled for surface characterization and catalytic activity. Even after calcination at $600^{\circ}C$, the structure and morphology of hybrid nanocatalysts remain intact confirm the high thermal stability. XPS spectra of hybrid nanocatalyst suggest the metallic states as well as their corresponding oxide states. The catalytic activity has been evaluated for high temperature CO oxidation reaction as well as photocatalytic H2 generation under solar simulation. The design of hybrid structure, high thermal stability, and better exposure of metal active sites are the key parameters for the high catalytic activity. The maximization of metal-TiO2 interface interaction has the great role in photocatalytic H2 production.

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Synthesis and Characterization of ZnO/TiO2 Photocatalyst Decorated with PbS QDs for the Degradation of Aniline Blue Solution

  • Lee, Jong-Ho;Ahn, Hong-Joo;Youn, Jeong-Il;Kim, Young-Jig;Suh, Su-Jeong;Oh, Han-Jun
    • Korean Journal of Metals and Materials
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    • v.56 no.12
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    • pp.900-909
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    • 2018

  • A $ZnO/TiO_2$ photocatalyst decorated with PbS quantum dots (QDs) was synthesized to achieve high photocatalytic efficiency for the decomposition of dye in aqueous media. A $TiO_2$ porous layer, as a precursor photocatalyst, was fabricated using micro-arc oxidation, and exhibited irregular porous cells with anatase and rutile crystalline structures. Then, a ZnO-deposited $TiO_2$ catalyst was fabricated using a zinc acetate solution, and PbS QDs were uniformly deposited on the surface of the $ZnO/TiO_2$ photocatalyst using the successive ionic layer adsorption and reaction (SILAR) technique. For the PbS $QDs/ZnO/TiO_2$ photocatalyst, ZnO and PbS nanoparticles are uniformly precipitated on the $TiO_2$ surface. However, the diameters of the PbS particles were very fine, and their shape and distribution were relatively more homogeneous compared to the ZnO particles on the $TiO_2$ surface. The PbS QDs on the $TiO_2$ surface can induce changes in band gap energy due to the quantum confinement effect. The effective band gap of the PbS QDs was calculated to be 1.43 eV. To evaluate their photocatalytic properties, Aniline blue decomposition tests were performed. The presence of ZnO and PbS nanoparticles on the $TiO_2$ catalysts enhanced photoactivity by improving the absorption of visible light. The PbS $QDs/ZnO/TiO_2$ heterojunction photocatalyst showed a higher Aniline blue decomposition rate and photocatalytic activity, due to the quantum size effect of the PbS nanoparticles, and the more efficient transport of charge carriers.

  • https://doi.org/10.3365/KJMM.2018.56.12.900 인용 KSCI

Effect of Graphene Oxide Addition to Tin Oxide Aerogel for Photocatalytic Rhodamine B Degradation (주석산화물 에어로겔의 Graphene Oxide 첨가에 따른 광촉매적 Rhodamine B 분해)

  • Kim, Taehee;Choi, Haryeong;Kim, Younghun;Lee, Jihun;Park, Hyung-Ho
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.1
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    • pp.61-66
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    • 2021

  • SnO2 has the wide bandgap which allows it to be used as the photocatalyst. There are many studies to enhance the photocatalytic properties of SnO2. In this study, 3-dimensional SnO2 aerogel was synthesized using epoxide-initiated sol-gel method for the optimal specific surface area. Also, graphene oxide (GO) was added before the gelation process of the aerogel to maximize the specific surface area. Addition of 0.5 wt% of GO would possibly enhance the specific surface area by 1.7 times compared with the bare tin oxide aerogel. Furthermore, enhanced specific surface area could degrade 67.3% of initial Rhodamine B in 120 minutes. To compare with the bare SnO2 aerogel, 0.5 wt% GO addition to SnO2 could double the reaction rate of the photocatalytic degradation.

  • https://doi.org/10.6117/kmeps.2021.28.1.061 인용 PDF KSCI

Synthesis of Ag-doped black ZnO nano-catalysts for the utilization of visible-light (가시광선 활용을 위한 Ag 도핑 흑색 ZnO 나노 광촉매 합성)

  • Ui-Jun Kim;Hye-Min Kim;Seung-Hyo Lee
    • Journal of the Korean institute of surface engineering
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    • v.56 no.3
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    • pp.208-218
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    • 2023

  • Photocatalysts are advanced materials which accelerate the photoreaction by providing ordinary reactions with other pathways. The catalysts have various advantages, such as low-cost, low operating temperature and pressure, and long-term use. They are applied to environmental and energy field, including the air and water purification, water splitting for hydrogen production, sterilization and self-cleaning surfaces. However, commercial photocatalysts only absorb ultraviolet light between 100 and 400 nm of wavelength which comprises only 5% in sunlight due to the wide band gap. In addition, rapid recombination of electron-hole pairs reduces the photocatalytic performance. Recently, studies on blackening photocatalysts by laser, thermal, and plasma treatments have been conducted to enhance the absorption of visible light and photocatalytic activity. The disordered structures could yield mid-gap states and vacancies could cause charge carrier trapping. Herein, liquid phase plasma (LPP) is adopted to synthesize Ag-doped black ZnO for the utilization of visible-light. The physical and chemical characteristics of the synthesized photocatalysts are analyzed by SEM/EDS, XRD, XPS and the optical properties of them are investigated using UV/Vis DRS and PL analyses. Lastly, the photocatalytic activity was evaluated using methylene blue as a pollutant.

  • https://doi.org/10.5695/JSSE.2023.56.3.208 인용 PDF