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Yoshida T, Ogawa M. A six-fold difference in structure results in a six-order difference in conductivity: silica shell nanoarchitectonics on carbon black particles. NANOSCALE 2022; 14:7480-7483. [PMID: 35545960 DOI: 10.1039/d2nr01714h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Carbon black (Ketchen Black with a particle size of several tens of nm) was coated with silica with a varied thickness of 2 and 12 nm. Carbon/silica core-shell particles were grafted with the γ-methacryloxypropylsilyl group to be homogeneously dispersed into a poly(methyl methacrylate) film. The electrical conductivity of the poly(methyl methacrylate) films containing carbon/silica particles was successfully controlled by the thickness of the silica layer; silica coating with 2 nm thickness gave a conducting film, while that with 12 nm thickness gave a less conducting film with a remarkable difference on the order of 106 (in volume conductivity).
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Affiliation(s)
- Takaaki Yoshida
- Graduate School of Creative Science and Engineering, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan
| | - Makoto Ogawa
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand.
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Cheepborisutikul SJ, Ogawa M. Suppressing the Photocatalytic Activity of Titania by Precisely Controlled Silica Coating. Inorg Chem 2021; 60:6201-6208. [PMID: 33715351 DOI: 10.1021/acs.inorgchem.0c03476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A homogeneous thin silica layer with the thickness of a few nanometers was successfully deposited on an anatase particle by the hydrolysis and condensation of tetraethyl orthosilicate. The heat treatment of the titania/silica hybrid at 1000 °C led to the densification of the silica layer on the anatase particles. The anatase particle after the silica coating did not transform to rutile, and no change in the crystallite size was seen by the heat treatment at 1000 °C. The coating and subsequent heating were repeated to vary the thickness of the silica layer to obtain each coating with similar thickness by each coating procedure (ca. 3 and 2 nm, before and after the heat treatment). The samples were evaluated for the photocatalytic decomposition of methylene blue by the UV irradiation to find that the decomposition became slower after the coating and subsequent heat treatment, and the repeated procedures led to further suppression of the photocatalytic decomposition of methylene blue. The quite small decomposition rate constant (0.01 h-1) was successfully achieved by the coating and subsequent heating for three times (the thickness of the dense silica layer was ca. 7 nm).
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Affiliation(s)
- Siraphat Jan Cheepborisutikul
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand
| | - Makoto Ogawa
- School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand
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Heterostructural transformation of mesoporous silica-titania hybrids. Sci Rep 2021; 11:3210. [PMID: 33547337 PMCID: PMC7864960 DOI: 10.1038/s41598-020-80584-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 12/15/2020] [Indexed: 12/13/2022] Open
Abstract
Mesoporous silica (SBA-15 with the BJH pore size of 8 nm) containing anatase nanoparticles in the pore with two different titania contents (28 and 65 mass%), which were prepared by the infiltration of the amorphous precursor derived from tetraisopropyl orthotitanate into the pore, were heat treated in air to investigate the structural changes (both mesostructure of the SBA-15 and the phase and size of the anatase in the pore). The mesostructure of the mesoporous silica and the particle size of anatase unchanged by the heat treatment up to 800 °C. The heat treatment at the temperature higher than 1000 °C resulted in the collapse of the mesostructure and the growth of anatase nanoparticles as well as the transformation to rutile, while the transformation of anatase to rutile was suppressed especially for the sample with the lower titania content (28 mass%). The resulting mesoporous silica-anatase hybrids exhibited higher benzene adsorption capacity (adsorption from water) over those heated at lower temperature, probably due to the dehydroxylation of the silanol group on the pore surface. The photocatalytic decomposition of benzene in water by the present hybrid heated at 1100 °C was efficient as that by P25, a benchmark photocatalyst.
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Yamaguchi T, Ogawa M. Hydrophilic Internal Pore and Hydrophobic Particle Surface of Organically Modified Mesoporous Silica Particle to Host Photochromic Molecules. CHEM LETT 2019. [DOI: 10.1246/cl.180908] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Tetsuo Yamaguchi
- Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand
| | - Makoto Ogawa
- Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand
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Ozmen N, Erdemoglu S, Gungordu A, Asilturk M, Turhan DO, Akgeyik E, Harper SL, Ozmen M. Photocatalytic degradation of azo dye using core@shell nano-TiO 2 particles to reduce toxicity. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:29493-29504. [PMID: 30136182 DOI: 10.1007/s11356-018-2942-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 08/08/2018] [Indexed: 06/08/2023]
Abstract
Clean and safe water is fundamental for human and environmental health. Traditional remediation of textile dye-polluted water with chemical, physical, and biological processes has many disadvantages. Due to this, nano-engineered materials are drawing more attention to this area. However, the widespread use of nano-particles for this purpose may lead to photocatalytic degradation of xenobiotics, while increasing the risk of nano-particle-induced ecotoxicity. Therefore, we comparatively evaluated the toxicity of novel synthesized core@shell TiO2 and SiO2 nano-particles to embryonic stages of Danio rerio and Xenopus laevis. The ability of photocatalytic destruction of the synthesized nano-particles was tested using toxic azo dye, disperse red 65, and the effects of reducing the toxicity were evaluated. The reflux process was used to synthesize catalysts in the study. The samples were characterized by scanning electron microscopy, X-ray fluorescence spectroscopy, X-ray diffractometry, BET surface area, and UV-vis-diffuse reflectance spectra. It was determined that the synthesized nano-particles had no significant toxic effect on D. rerio and X. laevis embryos. On the other hand, photocatalytic degradation of the dye significantly reduced lethal effects on embryonic stages of the organisms. Therefore, we suggest that specific nano-particles may be useful for water remediation to prevent human health and environmental impact. However, further risk assessment should be conducted for the ecotoxicological risks of nano-particles spilled in aquatic environments and the relationship of photocatalytic interaction with nano-particles and xenobiotics.
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Affiliation(s)
- Nesrin Ozmen
- Department of Mathematics and Science Education, Faculty of Education, Inonu University, 44280, Malatya, Turkey
| | - Sema Erdemoglu
- Department of Chemistry, Faculty of Arts and Science, Inonu University, 44280, Malatya, Turkey
| | - Abbas Gungordu
- Laboratory of Environmental Toxicology, Department of Biology, Faculty of Arts and Science, Inonu University, 44280, Malatya, Turkey
| | - Meltem Asilturk
- Department of Materials Science and Engineering, Faculty of Engineering, Akdeniz University, 07058, Antalya, Turkey
| | - Duygu Ozhan Turhan
- Laboratory of Environmental Toxicology, Department of Biology, Faculty of Arts and Science, Inonu University, 44280, Malatya, Turkey
| | - Emrah Akgeyik
- Department of Chemistry, Faculty of Arts and Science, Inonu University, 44280, Malatya, Turkey
| | - Stacey L Harper
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, 97331, USA
| | - Murat Ozmen
- Laboratory of Environmental Toxicology, Department of Biology, Faculty of Arts and Science, Inonu University, 44280, Malatya, Turkey.
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