The Experts below are selected from a list of 552 Experts worldwide ranked by ideXlab platform
Jin-ho Choy - One of the best experts on this subject based on the ideXlab platform.
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TiO2-pillared clays with well-ordered porous structure and excellent photocatalytic activity
RSC Advances, 2015Co-Authors: Jae-hun Yang, Seung-min Paek, Huiyan Piao, Ajayan Vinu, Ahmed A. Elzatahry, Jin-ho ChoyAbstract:TiO2-pillared clays with well-ordered porous structures are successfully prepared via incorporating TiO2 nanosol particles into the clays, where empty octahedral sites are partially modified with divalent metal ions such as Mg2+ and Fe2+. The prepared TiO2-pillared mica exhibits excellent photocatalytic activity, which can be controlled by tuning the optical transparency of clay support rather than the specific surface area of the hybrid catalysts.
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Exfoliation and Reassembling Route to Mesoporous Titania Nanohybrids
Chemistry of Materials, 2006Co-Authors: Seung-min Paek, Hyun Jung, Youngjun Lee, Man Park, Seong-ju Hwang, Jin-ho ChoyAbstract:To fabricate mesoporous photocatalysts with delaminated structure, the exfoliated layered titanate in aqueous solution was reassembled in the presence of anatase TiO2 nanosol particles to induce a great number of mesopores and eventually a large surface area of TiO2 photocatalysts. No (0l0) peaks corresponding to the layered titanate appear in the X-ray diffraction patterns of the reassembled hybrids, which suggests that the titanate nanosheets were randomly hybridized with TiO2 nanoparticles without any restacking into the layered phase. According to the high-resolution transmission electron microscopy images of these nanohybrids, the randomly oriented titanate nanosheets can be seen clearly along with TiO2 nanosol particles with spherical images, indicating that the exfoliated sheets are indeed incorporated with anatase nanosol particles to form porous materials. From N2 adsorption−desorption isotherms, these nanohybrids are fairly high in specific surface area and in mesoporosity for effective photocat...
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Microporous SiO2-TiO2 Nanosols pillared montmorillonite for photocatalytic decomposition of methyl orange
Journal of Photochemistry and Photobiology A-chemistry, 2005Co-Authors: Song Liu, Jae-hun Yang, Jin-ho ChoyAbstract:Abstract Layered nanohybrid, SiO 2 –TiO 2 sol pillared clay, has been prepared by ion exchange reaction of the sodium ion in montmorillonite with positively charged SiO 2 –TiO 2 sol particles. From powder X-ray diffraction (XRD), the basal spacing ( d 0 0 1 ) of sample calcined at 400 °C was found to be 4.65 nm, due to the multistacking of nanosized SiO 2 and TiO 2 sol particles, which was confirmed by micropore analysis calculated from nitrogen adsorption. The BET specific surface area shows the value of 446 m 2 /g and total porosity is found to be 0.28 ml/g, and the pores are mainly composed of micropore with a size of ca. 1.1 nm. TiO 2 particles stabilized in the interlayer space of montmorillonite are found to be quantum size according to UV–vis spectroscopy. The photocatalytic properties of the SiO 2 –TiO 2 pillars were investigated in the degradation of methyl orange in water. The optimal photocatalyst amount is 55 mg/l with the reaction rate constant being 0.33 h −1 . The presence of iron ions dopants does not influence or is detrimental for the occurrence of methyl orange photodegradation.
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Exfoliation and Restacking Route to Anatase-Layered Titanate Nanohybrid with Enhanced Photocatalytic Activity
Chemistry of Materials, 2002Co-Authors: Jin-ho Choy, Hyun-cheol Lee, Hyun Chae Jung, Hasuck Kim, Hankil BooAbstract:A new microporous TiO2-pillared layered titanate has been prepared by hybridizing the exfoliated titanate with the anatase TiO2 nanosol. The stable colloidal nano-sheet was obtained by intercalating tetrabutylamine into the layered protonic titanate, HxTi2-x/4□x/4O4·H2O (x = 0.67), with a lepidocrocite-like structure. The colloidal suspension of exfoliated titanate sheets was mixed with the monodispersed anatase TiO2 nanosol solution prepared by the hydrolysis of titanium isopropoxide with acetylacetone. The obtained nanohybrid was heated at 300 °C for 2 h in order to complete the grafting reaction of intercalated anatase TiO2 nanosol on the interlayer surface of layered titanate. According to the X-ray diffraction analysis and N2 adsorption−desorption isotherms, it was found that the TiO2-pillared layered titanate showed a pillar height of ∼2 nm, a high surface area of ∼460 m2/g, and a pore size of ∼0.95 nm, indicating the formation of a microporous pillar structure. Its photocatalytic activity was evalu...
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highly porous pillared clay with multistacked sio_2 tio_2 Nanosols
Bulletin of The Korean Chemical Society, 1998Co-Authors: Jin-ho Choy, J H Park, J B YoonAbstract:Layered nanocomposite, SiO2/TiO2 sol pillared clay, has been prepared by the ion exchange reaction of Na' ion in montmorillonite with positively charged mixed SiO2/TiO2 sol. The nanosized sol particles were synthesized by mixing SiO2 sol solution with TiO2 one, which is obtained by acidic hydrolysis of TEOS and TiCl4, respectively. From powder XRD, the basal spacing (d001) of the sample calcined at 400 ℃ was found to be ca. 60 Å, due to the multistacking of nanosized SiO2 and TiO2 sol particles, which was confirmed by the pore size analysis from 129Xe NMR and micropore analysis calculated from nitrogen adsorption. The BET specific surface area shows the value of 684 m2g-1 (Langmuir 1115 m2g-1), which is the highest among various pillared clays ever reported previously, and the total porosity is found to be 0.51 mlg-1, and the pores are mainly composed of micropore with a size of ca. 11.8 Å. This result agrees with the adsorption capacity obtained from water adsorption. According to diffuse reflectance ultraviolet-visible spectroscopy, it is found that the TiO2 particles stabilized in the interlayer space of montmorillonite are quantum-sized of ca. 20 Å.
Saad Zaghloul - One of the best experts on this subject based on the ideXlab platform.
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A New Facile Strategy for Multifunctional Textiles Development through In Situ Deposition of SiO2/TiO2 Nanosols Hybrid
Industrial & Engineering Chemistry Research, 2019Co-Authors: Tharwat I. Shaheen, Salem S. Salem, Saad ZaghloulAbstract:Herein, antibacterial activity and water repellent cotton fabrics with UV protection were carried out through in situ chemical deposition of SiO2 Nanosols. Ammonium hydroxide was used as a gentle catalyst to initiate the polycondensation reaction inside the fabrics. During deposition of SiO2 Nanosols onto cellulose of cotton, the process was integrated with TiO2 Nanosols to evaluate the cooperative properties of the formed SiO2/TiO2 Nanosols onto cotton fabrics. Furthermore, the water repellent property was induced to the loaded cotton fabrics by further polycondensation with octamethyltrisiloxane (OMTS). Results revealed that both SiO2 and TiO2 as well as mixtures therefrom were in situ deposited onto cotton fabrics, separately, in sizes ranging from 5–10 nm as indicated from TEM. Results from XRD and FTIR clearly proved, respectively, the crystallographic profile and chemical structure of Nanosols loaded inside cotton fabrics. By comparing the obtained results, UV protection and water repellent combined...
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a new facile strategy for multifunctional textiles development through in situ deposition of sio2 tio2 Nanosols hybrid
Industrial & Engineering Chemistry Research, 2019Co-Authors: Tharwat I. Shaheen, Salem S. Salem, Saad ZaghloulAbstract:Herein, antibacterial activity and water repellent cotton fabrics with UV protection were carried out through in situ chemical deposition of SiO2 Nanosols. Ammonium hydroxide was used as a gentle catalyst to initiate the polycondensation reaction inside the fabrics. During deposition of SiO2 Nanosols onto cellulose of cotton, the process was integrated with TiO2 Nanosols to evaluate the cooperative properties of the formed SiO2/TiO2 Nanosols onto cotton fabrics. Furthermore, the water repellent property was induced to the loaded cotton fabrics by further polycondensation with octamethyltrisiloxane (OMTS). Results revealed that both SiO2 and TiO2 as well as mixtures therefrom were in situ deposited onto cotton fabrics, separately, in sizes ranging from 5–10 nm as indicated from TEM. Results from XRD and FTIR clearly proved, respectively, the crystallographic profile and chemical structure of Nanosols loaded inside cotton fabrics. By comparing the obtained results, UV protection and water repellent combined...
Rongbin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Water-phase strategy for synthesis of TiO2–graphene composites with tunable structure for high performance photocatalysts
Applied Surface Science, 2014Co-Authors: Fei Chen, Chengjiang Lian, Shizheng Zheng, Shuwang Duo, Rongbin ZhangAbstract:Abstract The controllable synthesis of strongly coupled TiO2/graphene composites has been a long-standing challenge for developing advanced photocatalysts. Here, we report a facile water-phase protocol for synthesis of TiO2–graphene composites using GO aqueous suspension and TiO2 aqueous Nanosols as precursors. By controlling the ratio of GO to TiO2, both high-/low-dense TiO2 nanoparticles across graphene and graphene–TiO2–graphene sandwich structured composites are successfully achieved through electrostatic attraction between negatively charged GO nanosheets and positively charged TiO2 Nanosols. The TiO2–graphene composites show an enhanced photocatalytic activity for the degradation of methylene blue (MB) under UV light. Interestingly, the sandwich structured TiO2–graphene composite exhibits the best photocatalytic activity and the highest photocurrent density, which is 12.2 and 35.46 times as that of pure TiO2, respectively. The outstanding photocatalytic activity of sandwich structured composite is likely due to the following two reasons, two-channel electron conduction path between TiO2 and graphene, as well as the better adsorption capability of MB molecule.
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Aqueous production of TiO2–graphene nanocomposites by a combination of electrostatic attraction and hydrothermal process
Materials Letters, 2014Co-Authors: Fei Chen, Chengjiang Lian, Shizheng Zheng, Rongbin ZhangAbstract:Abstract TiO2–graphene (TOG) nanocomposites were prepared by combining electrostatic attraction and hydrothermal process, only using graphene oxide (GO) aqueous suspension and TiO2 aqueous Nanosols as precursors, without any other organic solvent and special organic reagent. XRD, TEM, and XPS spectra were applied to characterize the crystal phase, microstructure, and other physicochemical properties of samples. The results showed that graphene was covered by dense TiO2 nanoparticles (NPs) with a very fine grain size around 5–12 nm. The formation mechanism of TOG nanocomposites is considered to be caused by electrostatic attraction.
Tharwat I. Shaheen - One of the best experts on this subject based on the ideXlab platform.
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A New Facile Strategy for Multifunctional Textiles Development through In Situ Deposition of SiO2/TiO2 Nanosols Hybrid
Industrial & Engineering Chemistry Research, 2019Co-Authors: Tharwat I. Shaheen, Salem S. Salem, Saad ZaghloulAbstract:Herein, antibacterial activity and water repellent cotton fabrics with UV protection were carried out through in situ chemical deposition of SiO2 Nanosols. Ammonium hydroxide was used as a gentle catalyst to initiate the polycondensation reaction inside the fabrics. During deposition of SiO2 Nanosols onto cellulose of cotton, the process was integrated with TiO2 Nanosols to evaluate the cooperative properties of the formed SiO2/TiO2 Nanosols onto cotton fabrics. Furthermore, the water repellent property was induced to the loaded cotton fabrics by further polycondensation with octamethyltrisiloxane (OMTS). Results revealed that both SiO2 and TiO2 as well as mixtures therefrom were in situ deposited onto cotton fabrics, separately, in sizes ranging from 5–10 nm as indicated from TEM. Results from XRD and FTIR clearly proved, respectively, the crystallographic profile and chemical structure of Nanosols loaded inside cotton fabrics. By comparing the obtained results, UV protection and water repellent combined...
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a new facile strategy for multifunctional textiles development through in situ deposition of sio2 tio2 Nanosols hybrid
Industrial & Engineering Chemistry Research, 2019Co-Authors: Tharwat I. Shaheen, Salem S. Salem, Saad ZaghloulAbstract:Herein, antibacterial activity and water repellent cotton fabrics with UV protection were carried out through in situ chemical deposition of SiO2 Nanosols. Ammonium hydroxide was used as a gentle catalyst to initiate the polycondensation reaction inside the fabrics. During deposition of SiO2 Nanosols onto cellulose of cotton, the process was integrated with TiO2 Nanosols to evaluate the cooperative properties of the formed SiO2/TiO2 Nanosols onto cotton fabrics. Furthermore, the water repellent property was induced to the loaded cotton fabrics by further polycondensation with octamethyltrisiloxane (OMTS). Results revealed that both SiO2 and TiO2 as well as mixtures therefrom were in situ deposited onto cotton fabrics, separately, in sizes ranging from 5–10 nm as indicated from TEM. Results from XRD and FTIR clearly proved, respectively, the crystallographic profile and chemical structure of Nanosols loaded inside cotton fabrics. By comparing the obtained results, UV protection and water repellent combined...
Boris Mahltig - One of the best experts on this subject based on the ideXlab platform.
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Surface properties of sol–gel treated thermally modified wood
Journal of Sol-Gel Science and Technology, 2010Co-Authors: Boris Mahltig, Martin Arnold, Per LöthmanAbstract:The application of inorganic sol coating agents is a versatile method for wood surface functionalisation. However, the use of sols for the surface finishing of thermally modified wood (TMT) so far has not been investigated thoroughly. This paper reports on the surface properties of TMT treated with modified silica sols. The silica sols are modified with the inorganic colour pigment iron oxide red. Pigment distribution and height profiles of sol treated TMT are characterised by optical microscopy in 3D mode and by scanning electron microscopy. Selected evaluations are also repeated after artificial weathering of the coated wood specimens. Hydrophobic surface properties are determined using contact angle measurements. The coloration can be adjusted by the degree of pigmentation of the applied nanosol. Moreover, the water repellency of TMT is significantly enhanced by the sol treatment. Therefore, the application of pigment modified Nanosols could lead to TMT with improved weathering stability and a wider coloration spectrum.
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Vakuumimprägnierung poröser Metallwerkstücke mit anorganischen Nanosolen
Vakuum in Forschung und Praxis, 2010Co-Authors: Boris MahltigAbstract:Die Versiegelung von porosen Metallwerkstucken kann durch Anwendung von anorganischen Nanosolen gelingen. entscheidend fur die wirksame Versiegelung ist die Applikation der Nanosole mittels Vakuumimpragnierung. Geeignete Nanosole enthalten Partikel von Silizium/Aluminium-Mischoxiden, die zudem mit organischen Methylgruppen modifiziert sind. Die Nanosolpartikel sind kleiner 100 nm, wobei das Maximum der Grosenverteilung bei etwa 10nm liegt. Neben der Versiegelung von Metallwerkstucken kann zudem durch die Nanosol-Applikation eine Verbesserung der Korrosionsstabilitat erreicht werden. Eine Weiterentwicklung dieser Technologie ist somit insbesondere aussichtsreich fur Anwendungen im Werkzeugbau und fur Werkstucke im Automobilbau. Vacuum impregnation of porous metal materials with inorganic nanosol The sealing of porous metal pieces is possible by application of inorganic Nanosols. For suitable sealing it is necessary that the nansols are applied by vacuum impregnation. For sealing useful Nanosols contain particles of silicon/aluminium-oxide with a modification of organic methyl groups. The nanosol particles are smaller than 100nm and the maximum of the particle size distribution is around 10nm. Beside sealing of the metal pieces, also their stability against corrosion can be improved by this nanosol application. The further development of this technology is especially promising for applications in machine factory or automobile.
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Functionalising wood by nanosol application
Journal of Materials Chemistry, 2008Co-Authors: Boris Mahltig, Christiane Swaboda, Albert Roessler, Horst BöttcherAbstract:This report describes ways in which the properties of wood might be improved by application of silica and other inorganic Nanosols. Topics covered are: the synthesis and modification of inorganic Nanosols, and methods of applying them to wood to improve its mechanical properties; the use of modified silica sols to realise flame retardant, water repellent and antimicrobial properties; recent nanosol applications for protecting ThermoWood, for restoring and preserving wooden cultural artefacts, and as auxiliaries for improving commercial wood lacquers.
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functionalisation of textiles by inorganic sol gel coatings
Journal of Materials Chemistry, 2005Co-Authors: Boris Mahltig, Helfried Haufe, Horst BöttcherAbstract:The maintenance and improvement of current properties and the creation of new material properties are the most important reasons for the functionalisation of textiles. The coating of textiles with chemically or physically modified silica sols with particle diameters smaller than 50 nm (“Nanosols”) enables the manifold alteration of their physico-mechanical, optical, electrical and biological properties. Thus the protection of textiles against destruction and the creation of new advantageous functions can be realised. Prospective new products to be developed include textiles with water, oil and soil repellency and with antimicrobial properties. This article discusses recent results from applying modified silica Nanosols to the functionalisation of textiles.
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Functionalisation of textiles by inorganic sol–gel coatings
Journal of Materials Chemistry, 2005Co-Authors: Boris Mahltig, Helfried Haufe, Horst BöttcherAbstract:The maintenance and improvement of current properties and the creation of new material properties are the most important reasons for the functionalisation of textiles. The coating of textiles with chemically or physically modified silica sols with particle diameters smaller than 50 nm (“Nanosols”) enables the manifold alteration of their physico-mechanical, optical, electrical and biological properties. Thus the protection of textiles against destruction and the creation of new advantageous functions can be realised. Prospective new products to be developed include textiles with water, oil and soil repellency and with antimicrobial properties. This article discusses recent results from applying modified silica Nanosols to the functionalisation of textiles.
