The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers (DMMn) were investigated over sulfated titania in order to reveal the decisive factor controlling the react...The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers (DMMn) were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.展开更多
Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co...Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co-condensation reaction of methyltrimethoxysilane (MTMOS) and amine functional groups, n-(2-Aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS) and 3-aminopropyl-trimethoxysilane (APTMS) were selected to study the effect of amine functional groups on the enhancement of formaldehyde adsorption and degradation under a UV irradiation process. Physicocbemical properties of prepared photocatalysts were characterized with nitrogen adsorption-desorption isotherms measurement, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the APTMS/SiO2/TiO2 film demonstrated a degradation efficiency of 79% superior to those of SiO2/TrO2 and AEAPTMS/SiO2/TiO2 films due to the synergetic effect of adsorption and photocatalytic properties. The APTMS/SiO2/TiO2 film can be recycled with about 7% decreasing of degradation efficiency after seven cycles.展开更多
The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and pheno...The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and phenol. The X-ray diffraction (XRD) and infrared (IR) techniques were employed to characterize the prepared catalysts. The effect of the weight ratio of the 12-molybdosphoric acid to titania on the transesterification was investigated. A 13.1% yield of DPC and an 11.6% yield of methyl phenyl carbonate (MPC) were obtained over MPA-TiO2 with the weight ratio of MPA to TiO2 as 5:1.展开更多
Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-...Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-Vis diffuse reflectance spectrophotometer, and their photocatalytic activities were evaluated under UV and visible light, respec tively. The XRD results showed that all titania catalysts were anatase. More significantly, the crystallite size of nitrogen-doped titania increased with an increase in N/Ti proportion, and the doping of nitrogen could extend the absorption shoulder into the visible-light region, thus it possessed a higher visible-light activity illustrated by decolorization of methyl orange (65.3%) under the irradiation of visible light, whereas pure titania showed little of such kind of visible light activity. The UV-light activity of nitrogen-doped titania catalysts was worse than that of pure titania and Degussa P25. In the range of N/Ti proportion of 4-10 mol%, the activity of nitrogen-doped titania weakened appreciably in the visible-light region as the N/Ti proportion increased, whereas a reverse relationship existed under the irradiation of UV light.展开更多
Transition metal-doping could effectively extend the light response range of TiO _2 photocatalysts from the ultraviolet(UV)to the visible region.Co-doped brookite titanium dioxide(Co–TiO_2)photocatalysts were synthes...Transition metal-doping could effectively extend the light response range of TiO _2 photocatalysts from the ultraviolet(UV)to the visible region.Co-doped brookite titanium dioxide(Co–TiO_2)photocatalysts were synthesized via the hydrothermal method with titanium tetrachloride as the raw material and cobalt chloride hexahydrate as the dopant.The prepared Co–TiO_2 photocatalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and UV–Vis diffuse reflectance spectroscopy(UV–Vis DRS).The photocatalytic activities of Co–TiO _2 photocatalysts were evaluated by photocatalytic degradation of isopropanol alcohol(IPA),a typical volatile organic compound(VOC),under visible light.The influences ofdifferent Co doping rates,initial concentrations of IPA gas and the amounts of photocatalyst addition were also studied.At the same time,the enhancement mechanism ofcobalt ions as a trap for photogenerated holes was discussed.Thus,we found the optimum doping rate,initial concentration of IPA gas and amount of photocatalyst to add.The results show that the mesoporous Co–TiO _2 photocatalysts possess smaller size particles,larger specific surface area,lower forbidden bandgap energy(Eg)and better photocatalytic activity than pure brookite TiO _2.When the doping of Co was 7% by mass,the initial concentration ofIPA gas was 1.0×10^(-6 )mol/L and the addition of Co–TiO_2 photocatalysts was 50 mg,the best photocatalytic activity was achieved.Furthermore,the degradation rate ofIPA was up to 91%,which shows great potential for waste water treatment.展开更多
The nanoscale titania coated silica was prepared via a two-step precipitating approach, where the nanoscale silica nuclei were first prepared by passing an aqueous solution of sodium silicate through an ion-exchange r...The nanoscale titania coated silica was prepared via a two-step precipitating approach, where the nanoscale silica nuclei were first prepared by passing an aqueous solution of sodium silicate through an ion-exchange resin bed, then coated with the precipitation from hydrolyzed butyl titanate in an ethanol-hexane mixture at a low pH value in the presence of poly(ethylene oxide) polyamine salt(PPA) at a high temperature of 90 ℃. In the second-step precipitating process, the spontaneously precipitated titania shell on the silica nuclei was stabilized in the suspension solution with the help of the adsorption of PPA on the particles. A possible precipitating mechanism was suggested. Furthermore, the amorphous titania shell could undergo crystallization from the amorphous to the anatase structure at a high temperature of 650 ℃, and a further phase transition from the anatase to the rutile structure in the different sintering processes at a rising temperature of 750 ℃.展开更多
Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime go...Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.展开更多
Nanostructured pure-Ti O_2 and Cu3%-Ti O_2 were successfully synthesized via co-precipitation method. The X-ray diffraction(XRD) result proves that the synthesized sample were predominantly in anatase phase with size ...Nanostructured pure-Ti O_2 and Cu3%-Ti O_2 were successfully synthesized via co-precipitation method. The X-ray diffraction(XRD) result proves that the synthesized sample were predominantly in anatase phase with size in the range of 8~16 nm, which are in good agreement with the transmission electron microscopy data. Owing to doping of copper, not only did the thermal stability of the Ti O_2 decrease, but also a significant decrease in its particle size and a shift of the adsorption edge to a higher wavelength region appear. The activity of both pure-Ti O_2 and Cu3%-doped Ti O_2 was tested to study their ability to decolorize congo red(CR) dye in aqueous solution. We observed that the CR dye was decolorized faster by Cu3%-Ti O_2 than pure-Ti O_2. Results of this study demonstrate a potential application of the synthesized sample for decolorizing dye pollutants from aqueous waste.展开更多
Infection is one of the major causes of failure of orthopedic implants. Our previous study demonstrated that nanotube modification of the implant surface, together with nanotubes loaded with quaternized chitosan (hyd...Infection is one of the major causes of failure of orthopedic implants. Our previous study demonstrated that nanotube modification of the implant surface, together with nanotubes loaded with quaternized chitosan (hydroxypropyltrimethyl ammonium chloride chitosan, HACC), could effectively inhibit bacterial adherence and biofilm formation in vitro. Therefore, the aim of this study was to further investigate the in vitro cytocompatibility with osteogenic cells and the in vivo anti-infection activity of titanium implants with HACC-loaded nanotubes (NT-H). The titanium implant (Ti), nanotubes without polymer loading (NT), and nanotubes loaded with chitosan (NT-C) were fabricated and served as controls. Firstly, we evaluated the cytocompatibility of these specimens with human bone marrow-derived mesenchymal stem cells in vitro. The observation of cell attachment, proliferation, spreading, and viability in vitro showed that NT-H has improved osteogenic activity compared with Ti and NT-C. A prophylaxis rat model with implantation in the femoral medullary cavity and inoculation with methiciUin-resistant Staphylococcus aureus was established and evaluated by radiographical, microbiological, and histopathological assessments. Our in vivo study demonstrated that NT-H coatings exhibited significant anti-infection capability compared with the Ti and NT-C groups. In conclusion, HACC-loaded nanotubes fabricated on a titanium substrate show good compatibility with osteogenic cells and enhanced anti-infection ability in vivo, providing a good foundation for clinical application to combat orthopedic implant-associated infections.展开更多
Paratungstate-loaded titania catalysts were prepared %via% the addition of a series of aqueous solutions of paratungstate(denoted as W_ 7) into an isopropanol solution of Ti[OCH(CH_ 3)_ 2]_ 4 by means of the sol-gel m...Paratungstate-loaded titania catalysts were prepared %via% the addition of a series of aqueous solutions of paratungstate(denoted as W_ 7) into an isopropanol solution of Ti[OCH(CH_ 3)_ 2]_ 4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstate-loaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400 ℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO_ 2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.展开更多
Well-organized mesoporous titania particles and thin films were successfully synthesized by using tetrabutyl titanate as the inorganic precursor and triblock copolymer (Pluronic P123) as the template via evaporation...Well-organized mesoporous titania particles and thin films were successfully synthesized by using tetrabutyl titanate as the inorganic precursor and triblock copolymer (Pluronic P123) as the template via evaporationinduced self-assembly process. The resulting materials were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD). Fourier-transform infrared spectroscopy (FT-IR),Brunauer-Emmett-Teller (BET) and atomic force microscopy (AFM). Macro shape of mesoporous titania would greatly influence the mesostructure of materials, and the probable reasons were also discussed.展开更多
Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but rec...Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO_2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO_2 nanostructures for dye sensitized solar cells.展开更多
Ordered macroporous titania photonic crystals (PCs) and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacun...Ordered macroporous titania photonic crystals (PCs) and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures.展开更多
Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Tell...Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)surface area analysis.In the present system,AlCl3 functions as a nucleating agent and induces the formation of rutile TiO2.The influences of HCl and isopropanol concentrations on the purity and morphology of the rutile TiO2 were investigated.The purity of the rutile TiO2 increased with increasing concentration of HCl.Evenly dispersed rutile TiO2 particles with a spherical morphology were obtained when the HCl and isopropanol concentrations were 0.5 and 1 mol·L-1,respectively.Furthermore,the prepared TiO2 powders were used in adsorption tests of the heavy metal pollutant Cr(Ⅵ).Rutile TiO2 sample S-9 demonstrated greater adsorption performance and a removal efficiency that was greater than 99.95%after60 min of adsorption when the Cr(Ⅵ)concentration was 200 mg·L-1.The maximum adsorption capacity on rutile TiO2 was 28.9 mg·g-1.This work provides an easy path to prepare a high-performance rutile TiO2 adsorbent with potential applications in water pollution treatment.展开更多
Sodium ion batteries have a huge potential for large-scale energy storage for the low cost and abundance of sodium resources. In this work, a novel structure of ultrafine polycrystalline TiO2 nanofibers is prepared on...Sodium ion batteries have a huge potential for large-scale energy storage for the low cost and abundance of sodium resources. In this work, a novel structure of ultrafine polycrystalline TiO2 nanofibers is prepared on nickel foam/carbon cloth by a simple vapor deposition method. The as-prepared TiO2 nanofibers show excellent performance when used as anodes for sodium-ion batteries. Specifically, the TiO2 nanofibers@nickel foam electrode delivers a high reversible capacity of 263.2 m Ahg^-1 at 0.2 C and maintains a considerable capacity of 144.2 m Ahg^-1 at 10 C. The TiO2 nanofibers@carbon cloth electrode also shows excellent high-rate capability, sustaining a capacity of 148 m Ahg^-1 after 20 0 0 cycles at 10 C. It is believed that the novel nanofibrous structure increases the contact area with the electrolyte and greatly shortens the sodium ion diffusion distance, and meanwhile, the polycrystalline nature of nanofibers exposes more intercalation sites for sodium storage. Furthermore, the density functional theory calculations exhibit strong ionic interactions between the exposed TiO2(101) facets and sodium ions, leading to a preferable sodiation/desodiation process. The unique structural features endow the TiO2 nanofibers electrodes great advantages in rapid sodium storage with an outstanding high-rate capability.展开更多
The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry(DSC)and thermogravimetry(TG).The oxidation pathway of titania slag powder in air was divided into...The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry(DSC)and thermogravimetry(TG).The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves.The isothermal oxidation kinetics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method.The results revealed that the entire isothermal oxidation process comprises two stages.The kinetic mechanism of the first stage can be described as f(α) = 1.77(1-α) [-ln (1-α)]^((1.77-1)/1.77),f(α)= 1.97(1-α) [-ln (1-α)]^((1.97-1)/1.97),and f (α) = 1.18(1-α) [-ln (1-α)]^((1.18-1)/1.18).The kinetic mechanism of the second stage for all samples can be described as f (α)=1.5(1-α)^(2/3)[1-(1-α)^(1/3)]^(-1).The activation energies of titania slag powders with different sizes(d_(1)<0.075 mm,0.125 mm<d_(2)<0.150 mm,and 0.425 mm<d_(3)<0.600 mm)for different reaction degrees were calculated.For the given experimental conditions,the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction.The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion(for powders d_(1)<0.075 mm)and internal diffusion(for powders 0.125 mm<d_(2)<0.150 mm and 0.425 mm<d_(3)<0.600 mm).展开更多
Iron-doped titania nanoparticles exhibit a higher photocatalytic activity than pure TiO_2 for the degradation of nitrite. The optimum Fe-doped content in terms of activity is approximately 0.5%. The increase in photoa...Iron-doped titania nanoparticles exhibit a higher photocatalytic activity than pure TiO_2 for the degradation of nitrite. The optimum Fe-doped content in terms of activity is approximately 0.5%. The increase in photoactivity is probably due to the higher adsorption and the inhibition of electron-hole recombination. The photocatalytic oxidation reaction of nitrite over the Fe-doped TiO_2 catalyst follows zero-order kinetics, which is different from that over pure TiO_2. The reaction rate decreases linearly with the increase of the pH of the solution.展开更多
The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-...The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-ended and multiwall morphologies. The TiO 2 nanotubes before and after surface acid treatment were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and UV-VIS dispersive energy spectrophotometry(DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II in aqueous solutions. It was found that the order of photocatalytic activity was as follows: TiO 2 nanotubes treated with 1.0 mol/L H 2SO 4 solution (TiO 2(1.0M H 2SO 4) nanotubes)>TiO 2 nanotubes treated with 0.2 mol/L H 2SO 4 solution (TiO 2(0.2M H 2SO 4) nanotubes)>TiO 2 nanotubes >TiO 2 powder. This was attributed to the fact that TiO 2 nanotubes treated with H 2SO 4 was composed of smaller particles and had higher specific surface areas. Furthermore, the smaller TiO 2 particles were beneficial to the transfer and separation of photo-generated electrons and holes in the inner of and on the surface of TiO 2 particles and reduced the recombination of photo-generated electrons and holes. Acid treatment was particularly effective for TiO 2 nanotubes, this increase in activity was correlated with the concentration of H 2SO 4 solution.展开更多
The Kevlar/polytetrafluroethylene(Kevlar/PTFE) fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the po...The Kevlar/polytetrafluroethylene(Kevlar/PTFE) fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,No.21203220 and 21133011)China Postdoctoral Science Foundation(No.2014M551674)+1 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(No.1302070C)the National Basic Research Program of China(973 Program,No.2011CB201404)
文摘The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers (DMMn) were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.
基金supported by the Royal Golden Jubilee of Thailand Research Fundthe Department of Chemical Engineering at King Mongkut’s University of Technology Thonburi
文摘Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co-condensation reaction of methyltrimethoxysilane (MTMOS) and amine functional groups, n-(2-Aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS) and 3-aminopropyl-trimethoxysilane (APTMS) were selected to study the effect of amine functional groups on the enhancement of formaldehyde adsorption and degradation under a UV irradiation process. Physicocbemical properties of prepared photocatalysts were characterized with nitrogen adsorption-desorption isotherms measurement, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the APTMS/SiO2/TiO2 film demonstrated a degradation efficiency of 79% superior to those of SiO2/TrO2 and AEAPTMS/SiO2/TiO2 films due to the synergetic effect of adsorption and photocatalytic properties. The APTMS/SiO2/TiO2 film can be recycled with about 7% decreasing of degradation efficiency after seven cycles.
文摘The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and phenol. The X-ray diffraction (XRD) and infrared (IR) techniques were employed to characterize the prepared catalysts. The effect of the weight ratio of the 12-molybdosphoric acid to titania on the transesterification was investigated. A 13.1% yield of DPC and an 11.6% yield of methyl phenyl carbonate (MPC) were obtained over MPA-TiO2 with the weight ratio of MPA to TiO2 as 5:1.
基金the Open Fund of the Key Laboratory of Enhanced Heat and Energy Conservation of Chinese Ministry of Education, South China University of Technology.
文摘Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-Vis diffuse reflectance spectrophotometer, and their photocatalytic activities were evaluated under UV and visible light, respec tively. The XRD results showed that all titania catalysts were anatase. More significantly, the crystallite size of nitrogen-doped titania increased with an increase in N/Ti proportion, and the doping of nitrogen could extend the absorption shoulder into the visible-light region, thus it possessed a higher visible-light activity illustrated by decolorization of methyl orange (65.3%) under the irradiation of visible light, whereas pure titania showed little of such kind of visible light activity. The UV-light activity of nitrogen-doped titania catalysts was worse than that of pure titania and Degussa P25. In the range of N/Ti proportion of 4-10 mol%, the activity of nitrogen-doped titania weakened appreciably in the visible-light region as the N/Ti proportion increased, whereas a reverse relationship existed under the irradiation of UV light.
基金supported by the National Key Basic Research and Development Program of China ("973" program,nos. 2012CB720100 and 2014CB239300)the National Natural Science Foundation of China (nos.21406164 and 21466035)+1 种基金the Science and Technology Innovation Guide Funds of Civil Aviation Administration of China (MHRD20140209)the Fundamental Research Funds for the Central Universities (no.3122016L016)
文摘Transition metal-doping could effectively extend the light response range of TiO _2 photocatalysts from the ultraviolet(UV)to the visible region.Co-doped brookite titanium dioxide(Co–TiO_2)photocatalysts were synthesized via the hydrothermal method with titanium tetrachloride as the raw material and cobalt chloride hexahydrate as the dopant.The prepared Co–TiO_2 photocatalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and UV–Vis diffuse reflectance spectroscopy(UV–Vis DRS).The photocatalytic activities of Co–TiO _2 photocatalysts were evaluated by photocatalytic degradation of isopropanol alcohol(IPA),a typical volatile organic compound(VOC),under visible light.The influences ofdifferent Co doping rates,initial concentrations of IPA gas and the amounts of photocatalyst addition were also studied.At the same time,the enhancement mechanism ofcobalt ions as a trap for photogenerated holes was discussed.Thus,we found the optimum doping rate,initial concentration of IPA gas and amount of photocatalyst to add.The results show that the mesoporous Co–TiO _2 photocatalysts possess smaller size particles,larger specific surface area,lower forbidden bandgap energy(Eg)and better photocatalytic activity than pure brookite TiO _2.When the doping of Co was 7% by mass,the initial concentration ofIPA gas was 1.0×10^(-6 )mol/L and the addition of Co–TiO_2 photocatalysts was 50 mg,the best photocatalytic activity was achieved.Furthermore,the degradation rate ofIPA was up to 91%,which shows great potential for waste water treatment.
基金Supported by the State Key L aboratory of Shanghai Institute of Ceram ics and State Key L aboratory of Surface Physicsin China
文摘The nanoscale titania coated silica was prepared via a two-step precipitating approach, where the nanoscale silica nuclei were first prepared by passing an aqueous solution of sodium silicate through an ion-exchange resin bed, then coated with the precipitation from hydrolyzed butyl titanate in an ethanol-hexane mixture at a low pH value in the presence of poly(ethylene oxide) polyamine salt(PPA) at a high temperature of 90 ℃. In the second-step precipitating process, the spontaneously precipitated titania shell on the silica nuclei was stabilized in the suspension solution with the help of the adsorption of PPA on the particles. A possible precipitating mechanism was suggested. Furthermore, the amorphous titania shell could undergo crystallization from the amorphous to the anatase structure at a high temperature of 650 ℃, and a further phase transition from the anatase to the rutile structure in the different sintering processes at a rising temperature of 750 ℃.
基金supported by the National Natural Science Foundation of China(U1663225,21805280 and 21805220)the Youth Innovation Foundation of Xiamen City:3502Z20206085+4 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R52)The Opening Project of PCOSS,Xiamen University,201907the program of introducing Talents of discipline to Universities-111 Project(Grant No.B20002)the project“Depollut Air”of Interreg V France-Wallonie-Vlaanderenthe financial support from the China Scholarship Council(CSC)。
文摘Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.
文摘Nanostructured pure-Ti O_2 and Cu3%-Ti O_2 were successfully synthesized via co-precipitation method. The X-ray diffraction(XRD) result proves that the synthesized sample were predominantly in anatase phase with size in the range of 8~16 nm, which are in good agreement with the transmission electron microscopy data. Owing to doping of copper, not only did the thermal stability of the Ti O_2 decrease, but also a significant decrease in its particle size and a shift of the adsorption edge to a higher wavelength region appear. The activity of both pure-Ti O_2 and Cu3%-doped Ti O_2 was tested to study their ability to decolorize congo red(CR) dye in aqueous solution. We observed that the CR dye was decolorized faster by Cu3%-Ti O_2 than pure-Ti O_2. Results of this study demonstrate a potential application of the synthesized sample for decolorizing dye pollutants from aqueous waste.
基金financially supported by the National Natural Science Foundation of China (No.31271015,81501856)National Key R&D Program (2016YFC1102100)+1 种基金Shanghai Science and Technology Development Fund (13JC1403900,13DZ2294000)Medical Engineering Collaborative Project of Shanghai Jiao Tong University (YG2014ZD01)
文摘Infection is one of the major causes of failure of orthopedic implants. Our previous study demonstrated that nanotube modification of the implant surface, together with nanotubes loaded with quaternized chitosan (hydroxypropyltrimethyl ammonium chloride chitosan, HACC), could effectively inhibit bacterial adherence and biofilm formation in vitro. Therefore, the aim of this study was to further investigate the in vitro cytocompatibility with osteogenic cells and the in vivo anti-infection activity of titanium implants with HACC-loaded nanotubes (NT-H). The titanium implant (Ti), nanotubes without polymer loading (NT), and nanotubes loaded with chitosan (NT-C) were fabricated and served as controls. Firstly, we evaluated the cytocompatibility of these specimens with human bone marrow-derived mesenchymal stem cells in vitro. The observation of cell attachment, proliferation, spreading, and viability in vitro showed that NT-H has improved osteogenic activity compared with Ti and NT-C. A prophylaxis rat model with implantation in the femoral medullary cavity and inoculation with methiciUin-resistant Staphylococcus aureus was established and evaluated by radiographical, microbiological, and histopathological assessments. Our in vivo study demonstrated that NT-H coatings exhibited significant anti-infection capability compared with the Ti and NT-C groups. In conclusion, HACC-loaded nanotubes fabricated on a titanium substrate show good compatibility with osteogenic cells and enhanced anti-infection ability in vivo, providing a good foundation for clinical application to combat orthopedic implant-associated infections.
文摘Paratungstate-loaded titania catalysts were prepared %via% the addition of a series of aqueous solutions of paratungstate(denoted as W_ 7) into an isopropanol solution of Ti[OCH(CH_ 3)_ 2]_ 4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstate-loaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400 ℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO_ 2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.
文摘Well-organized mesoporous titania particles and thin films were successfully synthesized by using tetrabutyl titanate as the inorganic precursor and triblock copolymer (Pluronic P123) as the template via evaporationinduced self-assembly process. The resulting materials were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD). Fourier-transform infrared spectroscopy (FT-IR),Brunauer-Emmett-Teller (BET) and atomic force microscopy (AFM). Macro shape of mesoporous titania would greatly influence the mesostructure of materials, and the probable reasons were also discussed.
文摘Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO_2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO_2 nanostructures for dye sensitized solar cells.
基金This work was financially supported by the Beijing Foundation of Natural Science, China(No. Z012013).
文摘Ordered macroporous titania photonic crystals (PCs) and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures.
基金financially supported by the National Natural Science Foundation of China(Nos.51734002 and51774027)。
文摘Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)surface area analysis.In the present system,AlCl3 functions as a nucleating agent and induces the formation of rutile TiO2.The influences of HCl and isopropanol concentrations on the purity and morphology of the rutile TiO2 were investigated.The purity of the rutile TiO2 increased with increasing concentration of HCl.Evenly dispersed rutile TiO2 particles with a spherical morphology were obtained when the HCl and isopropanol concentrations were 0.5 and 1 mol·L-1,respectively.Furthermore,the prepared TiO2 powders were used in adsorption tests of the heavy metal pollutant Cr(Ⅵ).Rutile TiO2 sample S-9 demonstrated greater adsorption performance and a removal efficiency that was greater than 99.95%after60 min of adsorption when the Cr(Ⅵ)concentration was 200 mg·L-1.The maximum adsorption capacity on rutile TiO2 was 28.9 mg·g-1.This work provides an easy path to prepare a high-performance rutile TiO2 adsorbent with potential applications in water pollution treatment.
基金financial support from the National Natural Science Foundation of China (Nos. 51672210 , 21875183)the National Program for Support of Top-notch Young Professionals
文摘Sodium ion batteries have a huge potential for large-scale energy storage for the low cost and abundance of sodium resources. In this work, a novel structure of ultrafine polycrystalline TiO2 nanofibers is prepared on nickel foam/carbon cloth by a simple vapor deposition method. The as-prepared TiO2 nanofibers show excellent performance when used as anodes for sodium-ion batteries. Specifically, the TiO2 nanofibers@nickel foam electrode delivers a high reversible capacity of 263.2 m Ahg^-1 at 0.2 C and maintains a considerable capacity of 144.2 m Ahg^-1 at 10 C. The TiO2 nanofibers@carbon cloth electrode also shows excellent high-rate capability, sustaining a capacity of 148 m Ahg^-1 after 20 0 0 cycles at 10 C. It is believed that the novel nanofibrous structure increases the contact area with the electrolyte and greatly shortens the sodium ion diffusion distance, and meanwhile, the polycrystalline nature of nanofibers exposes more intercalation sites for sodium storage. Furthermore, the density functional theory calculations exhibit strong ionic interactions between the exposed TiO2(101) facets and sodium ions, leading to a preferable sodiation/desodiation process. The unique structural features endow the TiO2 nanofibers electrodes great advantages in rapid sodium storage with an outstanding high-rate capability.
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFC1900500)Graduate Research and Innovation Foundation of Chongqing,China(No.CYB17002).
文摘The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry(DSC)and thermogravimetry(TG).The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves.The isothermal oxidation kinetics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method.The results revealed that the entire isothermal oxidation process comprises two stages.The kinetic mechanism of the first stage can be described as f(α) = 1.77(1-α) [-ln (1-α)]^((1.77-1)/1.77),f(α)= 1.97(1-α) [-ln (1-α)]^((1.97-1)/1.97),and f (α) = 1.18(1-α) [-ln (1-α)]^((1.18-1)/1.18).The kinetic mechanism of the second stage for all samples can be described as f (α)=1.5(1-α)^(2/3)[1-(1-α)^(1/3)]^(-1).The activation energies of titania slag powders with different sizes(d_(1)<0.075 mm,0.125 mm<d_(2)<0.150 mm,and 0.425 mm<d_(3)<0.600 mm)for different reaction degrees were calculated.For the given experimental conditions,the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction.The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion(for powders d_(1)<0.075 mm)and internal diffusion(for powders 0.125 mm<d_(2)<0.150 mm and 0.425 mm<d_(3)<0.600 mm).
基金Grant-in-Aid for the COE project (Giant Molecules and Complex Systems) Steel Industry Foundation for the Advancement of Environmental Protection Technology
基金the National Natural Science Foundation of China.
文摘Iron-doped titania nanoparticles exhibit a higher photocatalytic activity than pure TiO_2 for the degradation of nitrite. The optimum Fe-doped content in terms of activity is approximately 0.5%. The increase in photoactivity is probably due to the higher adsorption and the inhibition of electron-hole recombination. The photocatalytic oxidation reaction of nitrite over the Fe-doped TiO_2 catalyst follows zero-order kinetics, which is different from that over pure TiO_2. The reaction rate decreases linearly with the increase of the pH of the solution.
文摘The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-ended and multiwall morphologies. The TiO 2 nanotubes before and after surface acid treatment were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and UV-VIS dispersive energy spectrophotometry(DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II in aqueous solutions. It was found that the order of photocatalytic activity was as follows: TiO 2 nanotubes treated with 1.0 mol/L H 2SO 4 solution (TiO 2(1.0M H 2SO 4) nanotubes)>TiO 2 nanotubes treated with 0.2 mol/L H 2SO 4 solution (TiO 2(0.2M H 2SO 4) nanotubes)>TiO 2 nanotubes >TiO 2 powder. This was attributed to the fact that TiO 2 nanotubes treated with H 2SO 4 was composed of smaller particles and had higher specific surface areas. Furthermore, the smaller TiO 2 particles were beneficial to the transfer and separation of photo-generated electrons and holes in the inner of and on the surface of TiO 2 particles and reduced the recombination of photo-generated electrons and holes. Acid treatment was particularly effective for TiO 2 nanotubes, this increase in activity was correlated with the concentration of H 2SO 4 solution.
文摘The Kevlar/polytetrafluroethylene(Kevlar/PTFE) fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.