High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-t...High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.展开更多
In the presence of Nafion/SiO2 nanocomposite catalyst, the benzylation of aromatic compounds with benzyl chloride proceeded to afford diphenylmethane derivatives in high yields. The catalyst showed high catalytic ac...In the presence of Nafion/SiO2 nanocomposite catalyst, the benzylation of aromatic compounds with benzyl chloride proceeded to afford diphenylmethane derivatives in high yields. The catalyst showed high catalytic activity not only for electron-rich aromatic compounds, but also for electron-poor aromatic compounds. Under identical conditions, the self-benzylation of benzyl chloride, and dibenzylation and/or multi-benzylation of aromatic compounds were negligible.展开更多
The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-p...The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique.The as-prepared nanocomposites and the nanocomposites coated samples were characterized by X-ray diffraction( XRD) and scanning electron microscopy( SEM),respectively.The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully.The photocatalytic activities of TiO 2-coated and TiO 2/ SiO 2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye.Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2/ SiO 2modified sample with respect to that of pure TiO 2modified sample.Our observations indicate that by applying this technique to the fabrics,self-cleaning materials can be designed for practical application.展开更多
LaF^3＋ Yb^3＋ , Er^3＋ nanoparticles were successfully synthesized using solvothermal treatment, and LaF^3＋ Yb^3＋ , Er^3＋/SiO2 core/shell nanoparticles were also prepared with reverse microemulsion technique. The ...LaF^3＋ Yb^3＋ , Er^3＋ nanoparticles were successfully synthesized using solvothermal treatment, and LaF^3＋ Yb^3＋ , Er^3＋/SiO2 core/shell nanoparticles were also prepared with reverse microemulsion technique. The crystal structure, morphology and photoluminescence properties of as-prepared core/shell nanoparticles were in- vestigated by X-ray diffraction, transmission electron microscopy and fluorescence spectrophotometer. The re- sults showed thatLaF^3＋ Yb^3＋ , Er^3＋ nanoparticles are of hexagonal structure and SiO2 shell is amorphous. The size ofLaF^3＋ Yb^3＋ , Er^3＋. nanoparticles is 13 nm and the LaF^3＋ Yb^3＋ , Er^3＋/SiO2 nanoparticles present clearly a core/shell structure with 12 nm shell thickness. The solubility of LaF^3＋ Yb^3＋ , Er^3＋ nanocrystals in water and the biocompatibility are both improved by the SiO2 shell. The upconversion luminescence spectra suggested that the SiO~ shell has small effect on the upconversion luminescence properties of the LaF^3＋ Yb^3＋ , Er^3＋ nanocrys- tals. The core/shell structure LaF^3＋ Yb^3＋ , Er^3＋ /SiO2. nanopartlcles are expected to be used in biological appli- cations.展开更多
The preparation of TiO2/poly（L-lactide-co-ε-caprolactone）（PLCL） nanocomposites and their properties were reported.TiO2nanoparticles were surface modified by ring-opening polymerization of ε-caprolactone（ε-CL）...The preparation of TiO2/poly（L-lactide-co-ε-caprolactone）（PLCL） nanocomposites and their properties were reported.TiO2nanoparticles were surface modified by ring-opening polymerization of ε-caprolactone（ε-CL）.The resulting poly（ε-caprolactone）-grafted TiO2（g-TiO2） was characterized by Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TGA） and transmission electron microscopy（TEM）.The g-TiO2can be uniformly dispersed in chloroform and the g-TiO2/PLCL nanocomposites were successfully fabricated through solvent-casting method.The effects of the content of g-TiO2nanoparticles on tensile properties and shape memory properties were investigated.A significant improvement in the tensile properties of the 5% g-TiO2/PLCL mass fraction nanocomposite is obtained：an increase of 113% in the tensile strength and an increase of 11% in the elongation at break over pure PLCL polymer.The g-TiO2/PLCL nanocomposites with a certain amount of g-TiO2content have better shape memory properties than pure PLCL polymer.The g-TiO2nanoparticles play an additional physical crosslinks which are contributed to improvement of the shape memory properties.展开更多
Given the nonuse of TiO2 nanoparticles as the reinforcement of AA2024 alloy in fabricating composites by ex-situ casting methods,it was decided to process the AA2024−xTiO2(np)(x=0,0.5 and 1 vol.%)nanocomposites by emp...Given the nonuse of TiO2 nanoparticles as the reinforcement of AA2024 alloy in fabricating composites by ex-situ casting methods,it was decided to process the AA2024−xTiO2(np)(x=0,0.5 and 1 vol.%)nanocomposites by employing the stir casting method.The structural properties of the produced samples were then investigated by optical microscopy and scanning electron microscopy;their mechanical properties were also addressed by hardness and tensile tests.The results showed that adding 1 vol.%TiO2 nanoparticles reduced the grain size and dendrite arm spacing by about 66%and 31%,respectively.Also,hardness,ultimate tensile strength,yield strength,and elongation of AA2024−1vol.%TiO2(np)composite were increased by about 25%,28%,4%and 163%,respectively,as compared to those of the monolithic component.The agglomerations of nanoparticles in the structure of nanocomposites were found to be a factor weakening the strength against the strengthening mechanisms.Some agglomerations of nanoparticles in the matrix were detected on the fractured surfaces of the tension test specimens.展开更多
An efficient visible-light-responsive BiOBr/TiO2 heterojunction nanocomposite was fabricated successfully using in-situ depositing technique at room temperature by introducing BiOBr onto the surface of TiO2 nano- belt...An efficient visible-light-responsive BiOBr/TiO2 heterojunction nanocomposite was fabricated successfully using in-situ depositing technique at room temperature by introducing BiOBr onto the surface of TiO2 nano- belts pre-prepared by hydrothermal reaction and etched with H2SO4. The obtained particles were characterized by XRD, SEM, TEM, XPS, UV-Vis DRS and PL techniques. BiOBr/TiO2 heterojunction nanocomposites with different mass ratios of m （BiOBr）/m （TiO2） were discussed in order to get the best photocatalytie activity, and BiOBr/TiO2-1.0 was proved to be the optimal mass ratio. BiOBr/TiO2-1.0 exhibited excellent photocatalytic activity in the degradation of RhB compared with TiO2 nanobelts, pure BiOBr and the mechanical mixture of TiO2 nanobelts and BiOBr. At last, a possible mechanism ofphotocatalytic enhancement was proposed.展开更多
Titanium dioxide/ kaolinite nanocomposite was prepared by the sol-gel method, with layered kaolinite as a substrate and Ti （ OC4H9 ）4 as a precursor. The effects of hydrolysis, drying and calcination on the producti...Titanium dioxide/ kaolinite nanocomposite was prepared by the sol-gel method, with layered kaolinite as a substrate and Ti （ OC4H9 ）4 as a precursor. The effects of hydrolysis, drying and calcination on the production of nanometric titanium dioxide were discussed. The optimal conditions for preparation were＂ bbtained through experiments. The 1- 10 nrn thick monolayer anatase nano TiO2 crystal was produced under the conditions as follows： hydrolyzed at 37-42 ℃ for 4 h, dried at 70-80 ℃ for 1 h, and calcined at 550-650℃ for 3 h. The rate of degradation of 40 mg/ L azo dye and 20 mg/ L acid red dye can reuch 96% and 81.45%, respectively.展开更多
One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface ...One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface contact in the fabricated nanocomposite greatly influences the charge transfer and separation so as to determine the final photocatalytic activities.However,the role of interface contact is often neglected,and is rarely reported to date.Hence,it is possible to further enhance the photocatalytic activity of g‐C3N4‐based nanocomposite by improving the interfacial connection.Herein,phosphate-oxygen(P-O)bridged TiO2/g‐C3N4nanocomposites were successfully synthesized using a simple wet chemical method,and the effects of the P-O functional bridges on the photogenerated charge separation and photocatalytic activity for pollutant degradation and CO2reduction were investigated.The photocatalytic activity of g‐C3N4was greatly improved upon coupling with an appropriate amount of nanocrystalline TiO2,especially with P-O bridged TiO2.Atmosphere‐controlled steady‐state surface photovoltage spectroscopy and photoluminescence spectroscopy analyses revealed clearly the enhancement of photogenerated charge separation of g‐C3N4upon coupling with the P-O bridged TiO2,resulting from the built P-O bridges between TiO2and g‐C3N4so as to promote effective transfer of excited electrons from g‐C3N4to TiO2.This enhancement was responsible for the improved photoactivity of the P-O bridged TiO2/g‐C3N4nanocomposite,which exhibited three‐time photocatalytic activity enhancement for2,4‐dichlorophenol degradation and CO2reduction compared with bare g‐C3N4.Furthermore,radical‐trapping experiments revealed that the·OH species formed as hole‐modulated direct intermediates dominated the photocatalytic degradation of2,4‐dichlorophenol.This work provides a feasible strategy for the design and synthesis of high‐performance g‐C3N4‐based nanocomposite photocatalysts for pollutant degradation and CO2reduction.展开更多
A resistive humidity sensor was prepared based on sodium polystyrenesulfonate (NaPSS)/TiO2 nanocomposites, and its electrical response to humidity was examined. The sensor exhibits better linearity, smaller hysteresis...A resistive humidity sensor was prepared based on sodium polystyrenesulfonate (NaPSS)/TiO2 nanocomposites, and its electrical response to humidity was examined. The sensor exhibits better linearity, smaller hysteresis (< 4% RH) and quicker response (absorption: less than 2 s; desorption: less than 20 s) in comparison with sensor composed of NaPSS. The effect of concentration of NaPSS and TiO2 on humidity response of sensors was discussed.展开更多
Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and super...Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and superparamagnetic properties.When the substrate temperature increases from room temperature to 400℃,Co particles gradually grow,and the degree of Co oxidation significantly decreases.Consequently,the saturation magnetization increases from 0.13 to 0.43 T at the same Co content by increasing the substrate temperature from room temperature to 400℃.At a high substrate temperature,conductive pathways form among some of the clustered Co particles.Thus,resistivity rapidly declines from 1600 to 76μΩ·m.The magnetoresistive characteristic of Co−TiO2 films is achieved even at resistivity of as low as 76μΩ·m.These results reveal that the obtained nanocomposite films have low Co oxidation,high magnetization and magnetoresistance at room temperature.展开更多
The dynamic wetting of water spreading on TiO 2 and TiO 2 SiO 2 films prepared by sol gel method and subsequently treated by air plasma and UV irradiation was investigated. Water completely spread on TiO 2 surface wit...The dynamic wetting of water spreading on TiO 2 and TiO 2 SiO 2 films prepared by sol gel method and subsequently treated by air plasma and UV irradiation was investigated. Water completely spread on TiO 2 surface within 3 s and its dynamic contact angles can be expressed by a power law θ d= k(t+a) -n with the n value 0.98. Less than 50%(molar fraction) SiO 2 addition can accelerate the dynamic water spreading rate on the TiO 2 SiO 2 films and the optimum molar fraction of SiO 2 amount corresponding to as annealed, air plasma, and UV irradiation treatment process is 15%, 10% and 20%, respectively.展开更多
文摘High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.
文摘In the presence of Nafion/SiO2 nanocomposite catalyst, the benzylation of aromatic compounds with benzyl chloride proceeded to afford diphenylmethane derivatives in high yields. The catalyst showed high catalytic activity not only for electron-rich aromatic compounds, but also for electron-poor aromatic compounds. Under identical conditions, the self-benzylation of benzyl chloride, and dibenzylation and/or multi-benzylation of aromatic compounds were negligible.
基金the Fundamental Research Funds for the Central Universities,China，China Postdoctoral Science
文摘The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique.The as-prepared nanocomposites and the nanocomposites coated samples were characterized by X-ray diffraction( XRD) and scanning electron microscopy( SEM),respectively.The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully.The photocatalytic activities of TiO 2-coated and TiO 2/ SiO 2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye.Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2/ SiO 2modified sample with respect to that of pure TiO 2modified sample.Our observations indicate that by applying this technique to the fabrics,self-cleaning materials can be designed for practical application.
文摘LaF^3＋ Yb^3＋ , Er^3＋ nanoparticles were successfully synthesized using solvothermal treatment, and LaF^3＋ Yb^3＋ , Er^3＋/SiO2 core/shell nanoparticles were also prepared with reverse microemulsion technique. The crystal structure, morphology and photoluminescence properties of as-prepared core/shell nanoparticles were in- vestigated by X-ray diffraction, transmission electron microscopy and fluorescence spectrophotometer. The re- sults showed thatLaF^3＋ Yb^3＋ , Er^3＋ nanoparticles are of hexagonal structure and SiO2 shell is amorphous. The size ofLaF^3＋ Yb^3＋ , Er^3＋. nanoparticles is 13 nm and the LaF^3＋ Yb^3＋ , Er^3＋/SiO2 nanoparticles present clearly a core/shell structure with 12 nm shell thickness. The solubility of LaF^3＋ Yb^3＋ , Er^3＋ nanocrystals in water and the biocompatibility are both improved by the SiO2 shell. The upconversion luminescence spectra suggested that the SiO~ shell has small effect on the upconversion luminescence properties of the LaF^3＋ Yb^3＋ , Er^3＋ nanocrys- tals. The core/shell structure LaF^3＋ Yb^3＋ , Er^3＋ /SiO2. nanopartlcles are expected to be used in biological appli- cations.
基金Project(50903023) supported by the National Natural Science Foundation of ChinaProject(HEUCF201210005) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2010RFQXG037) supported by Harbin Special Fund for Innovation Talents of Science and Technology,China
文摘The preparation of TiO2/poly（L-lactide-co-ε-caprolactone）（PLCL） nanocomposites and their properties were reported.TiO2nanoparticles were surface modified by ring-opening polymerization of ε-caprolactone（ε-CL）.The resulting poly（ε-caprolactone）-grafted TiO2（g-TiO2） was characterized by Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TGA） and transmission electron microscopy（TEM）.The g-TiO2can be uniformly dispersed in chloroform and the g-TiO2/PLCL nanocomposites were successfully fabricated through solvent-casting method.The effects of the content of g-TiO2nanoparticles on tensile properties and shape memory properties were investigated.A significant improvement in the tensile properties of the 5% g-TiO2/PLCL mass fraction nanocomposite is obtained：an increase of 113% in the tensile strength and an increase of 11% in the elongation at break over pure PLCL polymer.The g-TiO2/PLCL nanocomposites with a certain amount of g-TiO2content have better shape memory properties than pure PLCL polymer.The g-TiO2nanoparticles play an additional physical crosslinks which are contributed to improvement of the shape memory properties.
文摘Given the nonuse of TiO2 nanoparticles as the reinforcement of AA2024 alloy in fabricating composites by ex-situ casting methods,it was decided to process the AA2024−xTiO2(np)(x=0,0.5 and 1 vol.%)nanocomposites by employing the stir casting method.The structural properties of the produced samples were then investigated by optical microscopy and scanning electron microscopy;their mechanical properties were also addressed by hardness and tensile tests.The results showed that adding 1 vol.%TiO2 nanoparticles reduced the grain size and dendrite arm spacing by about 66%and 31%,respectively.Also,hardness,ultimate tensile strength,yield strength,and elongation of AA2024−1vol.%TiO2(np)composite were increased by about 25%,28%,4%and 163%,respectively,as compared to those of the monolithic component.The agglomerations of nanoparticles in the structure of nanocomposites were found to be a factor weakening the strength against the strengthening mechanisms.Some agglomerations of nanoparticles in the matrix were detected on the fractured surfaces of the tension test specimens.
基金Supported by the National Basic Research Program of China("973"Program,No.2014CB239300,No.2012CB720100)National Natural Science Foundation of China(No.21406164,No.21466035)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20110032110037,No.20130032120019)
文摘An efficient visible-light-responsive BiOBr/TiO2 heterojunction nanocomposite was fabricated successfully using in-situ depositing technique at room temperature by introducing BiOBr onto the surface of TiO2 nano- belts pre-prepared by hydrothermal reaction and etched with H2SO4. The obtained particles were characterized by XRD, SEM, TEM, XPS, UV-Vis DRS and PL techniques. BiOBr/TiO2 heterojunction nanocomposites with different mass ratios of m （BiOBr）/m （TiO2） were discussed in order to get the best photocatalytie activity, and BiOBr/TiO2-1.0 was proved to be the optimal mass ratio. BiOBr/TiO2-1.0 exhibited excellent photocatalytic activity in the degradation of RhB compared with TiO2 nanobelts, pure BiOBr and the mechanical mixture of TiO2 nanobelts and BiOBr. At last, a possible mechanism ofphotocatalytic enhancement was proposed.
基金Funded by National "973" Plan Research Project ( No.2004CB619204) and Educational Ministry Scientific and Technologi-cal Research Key Project (No.02052)
文摘Titanium dioxide/ kaolinite nanocomposite was prepared by the sol-gel method, with layered kaolinite as a substrate and Ti （ OC4H9 ）4 as a precursor. The effects of hydrolysis, drying and calcination on the production of nanometric titanium dioxide were discussed. The optimal conditions for preparation were＂ bbtained through experiments. The 1- 10 nrn thick monolayer anatase nano TiO2 crystal was produced under the conditions as follows： hydrolyzed at 37-42 ℃ for 4 h, dried at 70-80 ℃ for 1 h, and calcined at 550-650℃ for 3 h. The rate of degradation of 40 mg/ L azo dye and 20 mg/ L acid red dye can reuch 96% and 81.45%, respectively.
基金supported by the National Natural Science Foundation of China(U1401245,91622119)the Program for Innovative Research Team in Chinese Universities(IRT1237)+1 种基金the Research Project of Chinese Ministry of Education(213011A)the Science Foundation for Excellent Youth of Harbin City of China(2014RFYXJ002)~~
文摘One of the most general methods to enhance the separation of photogenerated carriers for g‐C3N4is to construct a suitable heterojunctional composite,according to the principle of matching energy levels.The interface contact in the fabricated nanocomposite greatly influences the charge transfer and separation so as to determine the final photocatalytic activities.However,the role of interface contact is often neglected,and is rarely reported to date.Hence,it is possible to further enhance the photocatalytic activity of g‐C3N4‐based nanocomposite by improving the interfacial connection.Herein,phosphate-oxygen(P-O)bridged TiO2/g‐C3N4nanocomposites were successfully synthesized using a simple wet chemical method,and the effects of the P-O functional bridges on the photogenerated charge separation and photocatalytic activity for pollutant degradation and CO2reduction were investigated.The photocatalytic activity of g‐C3N4was greatly improved upon coupling with an appropriate amount of nanocrystalline TiO2,especially with P-O bridged TiO2.Atmosphere‐controlled steady‐state surface photovoltage spectroscopy and photoluminescence spectroscopy analyses revealed clearly the enhancement of photogenerated charge separation of g‐C3N4upon coupling with the P-O bridged TiO2,resulting from the built P-O bridges between TiO2and g‐C3N4so as to promote effective transfer of excited electrons from g‐C3N4to TiO2.This enhancement was responsible for the improved photoactivity of the P-O bridged TiO2/g‐C3N4nanocomposite,which exhibited three‐time photocatalytic activity enhancement for2,4‐dichlorophenol degradation and CO2reduction compared with bare g‐C3N4.Furthermore,radical‐trapping experiments revealed that the·OH species formed as hole‐modulated direct intermediates dominated the photocatalytic degradation of2,4‐dichlorophenol.This work provides a feasible strategy for the design and synthesis of high‐performance g‐C3N4‐based nanocomposite photocatalysts for pollutant degradation and CO2reduction.
基金This work was supported by the National and Zhejiang Provincial Natural Science Foundation of China (No. 59773012).
文摘A resistive humidity sensor was prepared based on sodium polystyrenesulfonate (NaPSS)/TiO2 nanocomposites, and its electrical response to humidity was examined. The sensor exhibits better linearity, smaller hysteresis (< 4% RH) and quicker response (absorption: less than 2 s; desorption: less than 20 s) in comparison with sensor composed of NaPSS. The effect of concentration of NaPSS and TiO2 on humidity response of sensors was discussed.
基金Project(2016YFE0205700)supported by the National Key Research and Development Program of ChinaProject(18JCYBJC18000)supported by the Natural Science Foundation of Tianjin City,China。
文摘Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and superparamagnetic properties.When the substrate temperature increases from room temperature to 400℃,Co particles gradually grow,and the degree of Co oxidation significantly decreases.Consequently,the saturation magnetization increases from 0.13 to 0.43 T at the same Co content by increasing the substrate temperature from room temperature to 400℃.At a high substrate temperature,conductive pathways form among some of the clustered Co particles.Thus,resistivity rapidly declines from 1600 to 76μΩ·m.The magnetoresistive characteristic of Co−TiO2 films is achieved even at resistivity of as low as 76μΩ·m.These results reveal that the obtained nanocomposite films have low Co oxidation,high magnetization and magnetoresistance at room temperature.
文摘The dynamic wetting of water spreading on TiO 2 and TiO 2 SiO 2 films prepared by sol gel method and subsequently treated by air plasma and UV irradiation was investigated. Water completely spread on TiO 2 surface within 3 s and its dynamic contact angles can be expressed by a power law θ d= k(t+a) -n with the n value 0.98. Less than 50%(molar fraction) SiO 2 addition can accelerate the dynamic water spreading rate on the TiO 2 SiO 2 films and the optimum molar fraction of SiO 2 amount corresponding to as annealed, air plasma, and UV irradiation treatment process is 15%, 10% and 20%, respectively.
