Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray dif...Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Using the fibers as catalysts, photoeatalytic degradation of Methylene Blue (MB) aqueous solution was carded out under simulated sunlight. The 0.2% Ce doping proved to be the optimal concentration for the doping of TiO2/SiO2, compared to other Ce-doped molar concentrations. The 0.2% Ce-doped SiOdTiO2 fibers exhibited higher photocatalytic activity than industrial Degussa P25 and the samples doped with only Ce or SIO2. The reasons for improving the photocatalytic activity were also discussed. Several operational parameters were studied, which showed that the photocatalytic efficiency of MB was influenced by parameters such as the initial dye concentration, the initial pH, inorganic anions, and so on. In addition, the influences of an electron acceptor and a radical scavenger suggested that OH was the dominant photooxidant during the photocatalytic process. The reuse evaluation of the fibers indicated that their photocatalytic activity had good stability.展开更多
Nanosized SnO2 particles which are uniformly distributed are prepared through sol-gel process using anhydrous SnCl4 and iso-PrOH. By comgaring the results of XRD patterns with the JCPDS standard card of SnO2 and ahaly...Nanosized SnO2 particles which are uniformly distributed are prepared through sol-gel process using anhydrous SnCl4 and iso-PrOH. By comgaring the results of XRD patterns with the JCPDS standard card of SnO2 and ahalysing the TEM images of the product, we can prove that we got the narrow distributed SnO2 particles. The mean diameter of the particles is about 20 nm even sintered at 700℃ for 2 hours.展开更多
Nanosized amorphous TiO2 powders with a specific surface area of 501 m2·g-1 were prepared by hydrolysis. After calcined at 400℃ for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase cr...Nanosized amorphous TiO2 powders with a specific surface area of 501 m2·g-1 were prepared by hydrolysis. After calcined at 400℃ for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase crystallites with a specific surface area of 141 m2·g-1. Differential scanning calorimetric (DSC) experiments were performed on the samples of nanosized amorphous TiO2 mixed with microsized anatase, nanosized anatase, or nanosized α-Al2O3 respectively. Effects of sample packing, anatase addition, or α-Al2O3 addition on the crystallization behavior of nanosized amorphous TiO2 were analyzed.展开更多
The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particl...The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particles on the surface of TiO2 electrode extends the optical absorptionspectrum and photocurrent action specmim into visible region. In addition, compared with RuS2 bulknlaterials- a blue shifi in both absorption spectrum and photocurrent action speCtrum of RuS2rriO2elcctrode is obserived and explained in terms of quantum sized effect.展开更多
Iron(Ⅲ)-doped nanostructure TiO2-coated SiO2 (TiO2/SiO2) particles were prepared using the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized employing...Iron(Ⅲ)-doped nanostructure TiO2-coated SiO2 (TiO2/SiO2) particles were prepared using the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized employing the sol-gel method with TiChas a precursor. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), SEM, EDS, XPS, and XRD. The experimental results show that TiO2 nanopowders on the surface of SiO2 particles are well distributed, the amount of TiO2 is increased with the adding of coating layers, the pure anatase-TiO2 coating layers are synthesized at 500℃, and the photocatalytic activity of Fe^3+-doped TiO2/SiO2 is higher than that of undoped TiO2/SiO2.展开更多
Ni-Re/SiO2 catalysts with controllable Ni particle sizes(4.5–18.0 nm)were synthesized to investigate the effects of the particle size on the amination of monoethanolamine(MEA).The catalysts were characterized by vari...Ni-Re/SiO2 catalysts with controllable Ni particle sizes(4.5–18.0 nm)were synthesized to investigate the effects of the particle size on the amination of monoethanolamine(MEA).The catalysts were characterized by various techniques and evaluated for the amination reaction in a trickle bed reactor at 170℃,8.0 MPa,and 0.5 h^-1 liquid hourly space velocity of MEA(LHSVMEA)in NH3/H2 atmosphere.The Ni-Re/SiO2 catalyst with the lowest Ni particle size(4.5 nm)exhibited the highest yield(66.4%)of the desired amines(ethylenediamine(EDA)and piperazine(PIP)).The results of the analysis show that the turnover frequency of MEA increased slightly(from 193 to 253 h^-1)as the Ni particle sizes of the Ni-Re/SiO2 catalysts increased from 4.5 to 18.0 nm.Moreover,the product distribution could be adjusted by varying the Ni particle size.The ratio of primary to secondary amines increased from 1.0 to 2.0 upon increasing the Ni particle size from 4.5 to 18.0 nm.Further analyses reveal that the Ni particle size influenced the electronic properties of surface Ni,which in turn affected the adsorption of MEA and the reaction pathway of MEA amination.Compared to those of small Ni particles,large particles possessed a higher proportion of high-coordinated terrace Ni sites and a higher surface electron density,which favored the amination of MEA and NH3 to form EDA.展开更多
Using polystyrene (PSt) particles as template, PSt/TiO2 composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO3 and NaCl. AgCl doped TiO2 hollow p...Using polystyrene (PSt) particles as template, PSt/TiO2 composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO3 and NaCl. AgCl doped TiO2 hollow particles were successfully prepared with the PSt/TiO2 composite microspheres pretreated at 180 ℃ followed by calcination. The morphology of PSt/TiO2 particles and the crystal structures of the AgCl doped TiO2 hollow particles were characterized. The photocatalytic activity of the doped TiO2 hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO2 particles. The results showed that TiO2 hollow particles, either doped with Ag or AgCl, demonstrated higher photocatalytic activity than the pure TiO2 particles. This enhancement in photocatalytic activity was more significant with AgCl doped TiO2 than that with Ag doped, and more distinct when the degradation was done under visible light than that under UV light.展开更多
This work is focused on the combination of two building-blocks, nanocrystalline TiO2 particles and polyaniline conductive films (PAni). The preparation of new nanostructured composite materials, displaying electron-...This work is focused on the combination of two building-blocks, nanocrystalline TiO2 particles and polyaniline conductive films (PAni). The preparation of new nanostructured composite materials, displaying electron- and proton-conductive properties, to be used for the fabrication of new and superior energy storage devices was envisaged. The semiconducting TiO2 nanoparticles were obtained by means of a hydrothermal route. The PAni films were prepared on glassy carbon electrodes by electrochemical polymerization, under potential dynamic conditions. After characterization by X-ray diffraction, transmission electron microscopy or scanning electron microscopy and electrochemical techniques, the nanocrystalline particles were immobilized in the polymer matrix. The incorporation of the TiO2 was achieved using two distinct approaches: during the polymer growth or by deposition over previously prepared PAni films. The results demonstrate that the PAni morphology depends on the experimental conditions used during the polymer growth. After TiO2 immobilization, the best electrochemical response was obtained for the nanocomposite structure produced through the TiO2 incorporation after the PAni film synthesis. The modified electrodes were structurally and morphologically characterized and their electro-catalytic activity towards the hydrogen evolution reaction was analyzed. A new electrochemical performance related with the oxidation of molecular hydrogen entrapped in the PAni-TiO2 matrix was observed for the modified electrode after TiO2 incorporation. This behavior can be directly associated with the synergetic combination of the TiO2 and PAni, and is dependent on the amount of the semiconductor.展开更多
PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,wat...PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,water concentration and reaction temperature,have been investigated to control the thickness of silica shells.The shell thickness was prepositional to the square root of the initial concentration of TEOS and first increased with increasing water concentration,reached a maximum at about 2.0 mol/L and then started decreasing beyond that concentration.It was also found that the shell thickness decreased firstly with the reaction temperature added,then tended to a constant.The so-synthesized PS/SiO2 core-shell particles were directly crystallized into 3-D ordered thin film,then sintered at 570℃ into the ordered macroporous thin film.Compared with the conditional method,the present approach avoids repeatedly filling the precursor in the templetes and save time more.展开更多
In this study, novel core-shell SiO2-coated iron nanoparticles (SiO2-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effect...In this study, novel core-shell SiO2-coated iron nanoparticles (SiO2-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effects of ethanol/distilled water volume ratio, presence and absence of PEG, tetraethyl orthosilicate (TEOS) dosage, and hydrolysis time used in the nanoparticles preparation process were investigated. The results indicated that the SiO2-coated iron nanoparticles had the highest reduction activity when the particles synthesized with ethanol/H2O ratio of 2:1, PEG of 0.15 ml, TEOS of 0.5 ml and the reaction time was 4 h. The SiO2-nZVI nanoparticles were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometry (EDS) and powder X-Ray Diffraction (XRD). The results showed that the average particles diameter of the SiO2-nZVI was 20 - 30 nm. The thickness of the outside SiO2 film is consistent and approximately 10 nm. The results indicated that the nanoparticles coated completely with a transparent SiO2-film. Such nanoparticles could have wide applications in dye decolorization.展开更多
基金supported by the National Natural Science Foundation of China (No. 20907022,21003094)the Doctoral Program of Higher Education of China(No. 200800551003,20100032120066)the Special Projects of Environmental Protection (No. 2009ZX07526,2009ZX07208,200909101,2009GJA10021)
摘要Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Using the fibers as catalysts, photoeatalytic degradation of Methylene Blue (MB) aqueous solution was carded out under simulated sunlight. The 0.2% Ce doping proved to be the optimal concentration for the doping of TiO2/SiO2, compared to other Ce-doped molar concentrations. The 0.2% Ce-doped SiOdTiO2 fibers exhibited higher photocatalytic activity than industrial Degussa P25 and the samples doped with only Ce or SIO2. The reasons for improving the photocatalytic activity were also discussed. Several operational parameters were studied, which showed that the photocatalytic efficiency of MB was influenced by parameters such as the initial dye concentration, the initial pH, inorganic anions, and so on. In addition, the influences of an electron acceptor and a radical scavenger suggested that OH was the dominant photooxidant during the photocatalytic process. The reuse evaluation of the fibers indicated that their photocatalytic activity had good stability.
摘要Nanosized SnO2 particles which are uniformly distributed are prepared through sol-gel process using anhydrous SnCl4 and iso-PrOH. By comgaring the results of XRD patterns with the JCPDS standard card of SnO2 and ahalysing the TEM images of the product, we can prove that we got the narrow distributed SnO2 particles. The mean diameter of the particles is about 20 nm even sintered at 700℃ for 2 hours.
基金Financial support for this study was provided by the National Natural Science Foundation of China(Project No.50006014)
摘要Nanosized amorphous TiO2 powders with a specific surface area of 501 m2·g-1 were prepared by hydrolysis. After calcined at 400℃ for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase crystallites with a specific surface area of 141 m2·g-1. Differential scanning calorimetric (DSC) experiments were performed on the samples of nanosized amorphous TiO2 mixed with microsized anatase, nanosized anatase, or nanosized α-Al2O3 respectively. Effects of sample packing, anatase addition, or α-Al2O3 addition on the crystallization behavior of nanosized amorphous TiO2 were analyzed.
摘要The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particles on the surface of TiO2 electrode extends the optical absorptionspectrum and photocurrent action specmim into visible region. In addition, compared with RuS2 bulknlaterials- a blue shifi in both absorption spectrum and photocurrent action speCtrum of RuS2rriO2elcctrode is obserived and explained in terms of quantum sized effect.
基金the Nationnal Natural Science Foundation of China (No. 50342016).
摘要Iron(Ⅲ)-doped nanostructure TiO2-coated SiO2 (TiO2/SiO2) particles were prepared using the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized employing the sol-gel method with TiChas a precursor. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), SEM, EDS, XPS, and XRD. The experimental results show that TiO2 nanopowders on the surface of SiO2 particles are well distributed, the amount of TiO2 is increased with the adding of coating layers, the pure anatase-TiO2 coating layers are synthesized at 500℃, and the photocatalytic activity of Fe^3+-doped TiO2/SiO2 is higher than that of undoped TiO2/SiO2.
基金supported by the National Natural Science Foundation of China(21273227)Strategic Priority Research Program of Chinese Academy of Sciences(XDB17000000)~~
摘要Ni-Re/SiO2 catalysts with controllable Ni particle sizes(4.5–18.0 nm)were synthesized to investigate the effects of the particle size on the amination of monoethanolamine(MEA).The catalysts were characterized by various techniques and evaluated for the amination reaction in a trickle bed reactor at 170℃,8.0 MPa,and 0.5 h^-1 liquid hourly space velocity of MEA(LHSVMEA)in NH3/H2 atmosphere.The Ni-Re/SiO2 catalyst with the lowest Ni particle size(4.5 nm)exhibited the highest yield(66.4%)of the desired amines(ethylenediamine(EDA)and piperazine(PIP)).The results of the analysis show that the turnover frequency of MEA increased slightly(from 193 to 253 h^-1)as the Ni particle sizes of the Ni-Re/SiO2 catalysts increased from 4.5 to 18.0 nm.Moreover,the product distribution could be adjusted by varying the Ni particle size.The ratio of primary to secondary amines increased from 1.0 to 2.0 upon increasing the Ni particle size from 4.5 to 18.0 nm.Further analyses reveal that the Ni particle size influenced the electronic properties of surface Ni,which in turn affected the adsorption of MEA and the reaction pathway of MEA amination.Compared to those of small Ni particles,large particles possessed a higher proportion of high-coordinated terrace Ni sites and a higher surface electron density,which favored the amination of MEA and NH3 to form EDA.
摘要Using polystyrene (PSt) particles as template, PSt/TiO2 composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO3 and NaCl. AgCl doped TiO2 hollow particles were successfully prepared with the PSt/TiO2 composite microspheres pretreated at 180 ℃ followed by calcination. The morphology of PSt/TiO2 particles and the crystal structures of the AgCl doped TiO2 hollow particles were characterized. The photocatalytic activity of the doped TiO2 hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO2 particles. The results showed that TiO2 hollow particles, either doped with Ag or AgCl, demonstrated higher photocatalytic activity than the pure TiO2 particles. This enhancement in photocatalytic activity was more significant with AgCl doped TiO2 than that with Ag doped, and more distinct when the degradation was done under visible light than that under UV light.
基金supported by FCT-Fundacao para a Ciencia e Tecnologia under the project PTDC/CTM NAN/113021/2009O.C.Monteiro acknowledges PEst-OE/QUI/UI0612/2013 and Programme Ciencia 2007
摘要This work is focused on the combination of two building-blocks, nanocrystalline TiO2 particles and polyaniline conductive films (PAni). The preparation of new nanostructured composite materials, displaying electron- and proton-conductive properties, to be used for the fabrication of new and superior energy storage devices was envisaged. The semiconducting TiO2 nanoparticles were obtained by means of a hydrothermal route. The PAni films were prepared on glassy carbon electrodes by electrochemical polymerization, under potential dynamic conditions. After characterization by X-ray diffraction, transmission electron microscopy or scanning electron microscopy and electrochemical techniques, the nanocrystalline particles were immobilized in the polymer matrix. The incorporation of the TiO2 was achieved using two distinct approaches: during the polymer growth or by deposition over previously prepared PAni films. The results demonstrate that the PAni morphology depends on the experimental conditions used during the polymer growth. After TiO2 immobilization, the best electrochemical response was obtained for the nanocomposite structure produced through the TiO2 incorporation after the PAni film synthesis. The modified electrodes were structurally and morphologically characterized and their electro-catalytic activity towards the hydrogen evolution reaction was analyzed. A new electrochemical performance related with the oxidation of molecular hydrogen entrapped in the PAni-TiO2 matrix was observed for the modified electrode after TiO2 incorporation. This behavior can be directly associated with the synergetic combination of the TiO2 and PAni, and is dependent on the amount of the semiconductor.
基金Supported by the National Natural Science Foundation of China(No.:20221603)
摘要PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,water concentration and reaction temperature,have been investigated to control the thickness of silica shells.The shell thickness was prepositional to the square root of the initial concentration of TEOS and first increased with increasing water concentration,reached a maximum at about 2.0 mol/L and then started decreasing beyond that concentration.It was also found that the shell thickness decreased firstly with the reaction temperature added,then tended to a constant.The so-synthesized PS/SiO2 core-shell particles were directly crystallized into 3-D ordered thin film,then sintered at 570℃ into the ordered macroporous thin film.Compared with the conditional method,the present approach avoids repeatedly filling the precursor in the templetes and save time more.
摘要In this study, novel core-shell SiO2-coated iron nanoparticles (SiO2-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effects of ethanol/distilled water volume ratio, presence and absence of PEG, tetraethyl orthosilicate (TEOS) dosage, and hydrolysis time used in the nanoparticles preparation process were investigated. The results indicated that the SiO2-coated iron nanoparticles had the highest reduction activity when the particles synthesized with ethanol/H2O ratio of 2:1, PEG of 0.15 ml, TEOS of 0.5 ml and the reaction time was 4 h. The SiO2-nZVI nanoparticles were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometry (EDS) and powder X-Ray Diffraction (XRD). The results showed that the average particles diameter of the SiO2-nZVI was 20 - 30 nm. The thickness of the outside SiO2 film is consistent and approximately 10 nm. The results indicated that the nanoparticles coated completely with a transparent SiO2-film. Such nanoparticles could have wide applications in dye decolorization.