Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To bre...Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To break the mindset of magneticderivative design,and make up the shortage of monometallic non-magnetic derivatives,we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption.The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415(TiZr-MOFs)are qualified with a minimum reflection loss of−67.8 dB(2.16 mm,13.0 GHz),and a maximum effective absorption bandwidth of 5.9 GHz(2.70 mm).Through in-depth discussions,the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed.Therefore,this work confirms the huge potentials of nonmagnetic bimetallic MOFs derivatives in EMW absorption applications.展开更多
TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μ...TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.展开更多
In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% ...In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (εr) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of εr = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.展开更多
TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to es...TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content in TAs on the degradation rate.展开更多
Polyaniline(PAn)sensitized nanocrystalline TiO2 composites(TiO2/PAn)were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue(MB).The results showed that PAn was able ...Polyaniline(PAn)sensitized nanocrystalline TiO2 composites(TiO2/PAn)were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue(MB).The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light(λ:190~800 nm),whereas pure TiO2 absorbed ultraviolet light only(λ〈380 nm).Under the irradiation of natural light,MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore,it could be easily separated from the solution by simple sedimentation.展开更多
A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light (λ≥ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was emplo...A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light (λ≥ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.展开更多
Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle nature...Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle natureof silica materials and cumbersome preparation processes. In this paper,titania( TiO_2) was introduced into SiO_2 matrix to form photocatalytic hybrid gels. The TiO_2/SiO_2 composites were then reinforced by the impregnation of various fibrillary reinforcements,such as glass,mullite mineral and ceramic fibers. The properties of the composites were studied systematically in terms of fiberstability,microstructure,chemical interaction and thermal conductivity. The final xerogel composites displayed improved monolithic geometry,satisfied thermal conductivity(0. 09-0. 25 W·m-1·K-1) and optimized photocatalytic performance(85% removal of model pollutant of methyl orange( Mo)),which could be expected to be a feasible route to multi-functional building facades in the future.展开更多
We report the construction of a grapheneourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state ...We report the construction of a grapheneourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.展开更多
Cu2O/TiOa/Pt three-layer films were deposited on glass substrates using magnetron sputtering method. The surface morphology and the optical properties of the composite film were characterized by X-ray diffraction (XR...Cu2O/TiOa/Pt three-layer films were deposited on glass substrates using magnetron sputtering method. The surface morphology and the optical properties of the composite film were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet- visible spectroscopy (UV-Vis) and photoluminescence spectroscopy (PL). The photocatalytic activity of the samples was evaluated by the photocatalytic degradation of methyl orange (MO) aqueous solution under visible light irradiation. The results indicate that the Cu2O/TiO2/Pt composite films are made up of three layers which are Pt layer, anatase-TiO2 layer and Cu2O layer from bottom to top. The surface of the films is even and composed of regular-shaped spherical particles. The photocatalytic activity of the Cu2O/TiO2/Pt three-layer film is much higher than that of the Cu2O/TiO2 double-layer film. Such enhancement is ascribed to the presence of Pt layer, which further inhibits the photogenerated electron-hole recombination, prolongs the lifetime of the photogenerated carriers, increases the quantum efficiency and hence improves the photocatalytic activity of the film effectively.展开更多
We report a facile method for the fabrication of TiO2 nanofiber-nanoparticle composite (FP) via. simulta- neous electrospraying and electrospinning for dye-sensitized solar cell (DSC) applications. The loading of ...We report a facile method for the fabrication of TiO2 nanofiber-nanoparticle composite (FP) via. simulta- neous electrospraying and electrospinning for dye-sensitized solar cell (DSC) applications. The loading of nanoparticles on the fibers is controlled by varying their feed rates during electrospinning. The FP composites having three different particle loading are prepared by the methodology and the FP with the highest particle loading (denoted as FP-3 in the manuscript) showed the best overall efficiency of 9.15% in comparison to the other compositions of the FP (FP-2, 8.15% and FP-1, Z51%, respectively) and nanofibers (F) and nanoparticles (P) separately (7.21 and 7.81, respectively). All the material systems are characterized by spec- troscopy, microscopy, surface area measurements and the devices are characterized by current-voltage (I-V), incident photon-to-current conversion efficiency (IPCE), electrochemical impedance measurements, etc. I-V, dye-loading and reflectance measurements throw light on the overall performance of the DSC devices.展开更多
In the present work, composites of poly (methyl methacrylate)itanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their ...In the present work, composites of poly (methyl methacrylate)itanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their importance broad practical and medical applications. Thermal properties as well as X-ray diffraction analyses were employed to characterize the structure properties of such composite. The obtained results showed variations in the glass transition temperature (Tg), the melting temperature (Tm), shape and area of thermal peaks which were attributed to the different degrees of crystallinity and the existence of interactions between PMMA and TiO2 nanoparticle molecules. The XRD patterns showed sharpening of peaks at different concentrations of nano-TiO2 powder with PMMA. This indicated changes in the crystallinity/amorphosity ratio, and also suggested that the miscibility between the amorphous components of homo- polymers PMMA and nano-TiO2 powder is possible.The results showed that nano-TiO2 powder mix with PMMA can improve the thermal stability of the homo-polymer under investigation, lead- ing to interesting technological applications.展开更多
Solid state NMR was successfully used to determine the proton spin-lattice relaxation time in the rotating frame (T1ρH) for systems based on polypropylene (PP) and PP with titanium dioxide (TiO2) organically modified...Solid state NMR was successfully used to determine the proton spin-lattice relaxation time in the rotating frame (T1ρH) for systems based on polypropylene (PP) and PP with titanium dioxide (TiO2) organically modified or unmodified incorporated, in order to understand the molecular behavior of these systems. These techniques were employed in the samples organically modified and unmodified TiO2 to investigate the effect of organic modification on the dispersion and distribution of the particles in the PP matrix. The results were analyzed in terms of the effect of the particles organic modified or not according to the intermolecular interaction in the composites. According to the T1ρH values, all composites showed at least two domains: the short values were related to the rigid part, which included the crystalline and amorphous phase constricted in it, while the longer times were attributed to the amorphous region, which had higher molecular mobility compared to the rigid region of the materials. The increase in the relaxation time parameter in the composites compared to the pure PP was associated to the strong interaction between titanium dioxide particles and the polymer chains. This effect was more pronounced for the systems containing organically modified TiO2. According to the results, it could be inferred that intermolecular interaction occurred in the CH2 and CH groups, being more intense with CH2 groups. Finally, the solid state NMR techniques were able to evaluate the molecular dynamics of those systems.展开更多
Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 ...Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD(chemical oxygen demand) in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.展开更多
ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr(OH)4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope (...ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr(OH)4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) spectrophotometer. The composite film shows a lamellar and porous structure which consists of anatase, futile and ZrO2 phases. The optical absorption edge of film is shifted to longer wavelength when ZrO2 is introduced to TiO2. Furthermore, the photocatalytic reaction rate constants of degradation of rhodamine B solution with ZrO2/TiO2 composite film and pure TiO2 film under ultraviolet irradiation are measured as 0.0442 and 0.0186 h 1, respectively.展开更多
Bi2(Te,Se)3 alloys are conventional commercial thermoelectric materials for solid-state refrigeration around room temperature.In recent years,much attention has been paid to various advanced thermoelectric composite m...Bi2(Te,Se)3 alloys are conventional commercial thermoelectric materials for solid-state refrigeration around room temperature.In recent years,much attention has been paid to various advanced thermoelectric composite materials due to the unique thermoelectric properties.In this work,Bi2Se3/TiO2 composites were prepared by hot pressing the plate-like Bi2Se3 powders coated in situ with hydrolyzed hytetabutyl-n-butyl titanate(TNBT),and therefore numerous TiO2 in micrometer size could be formed on the interface of Bi2Se3 grains.The carrier concentration in Bi2Se3 matrix is optimized subject to the addition of n-type semiconductor TiO2,contributing to a significant improved power factor.In the meantime,the lattice thermal conductivity is also suppressed due to the enhanced phonon scattering at Bi2Se3/TiO2 interface and amorphous TiO2 particles.As a consequence,a peak figure of merit(zT)of 0.41 is obtained at 525 K in Bi2Se3/15 mol%TiO2 composites,nearly 50%augment over the pristine Bi2Se3 binary compound.展开更多
基金The authors acknowledge funding from the National Natural Science Foundation of China(Nos.51572157,21902085,and 51702188)Natural Science Foundation of Shandong Province(No.ZR2019QF012)+1 种基金Fundamental Research Funds for the Central Universities(No.2018JC036 and No.2018JC046)Young Scholars Program of Shandong University(No.2018WLJH25).
摘要Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To break the mindset of magneticderivative design,and make up the shortage of monometallic non-magnetic derivatives,we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption.The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415(TiZr-MOFs)are qualified with a minimum reflection loss of−67.8 dB(2.16 mm,13.0 GHz),and a maximum effective absorption bandwidth of 5.9 GHz(2.70 mm).Through in-depth discussions,the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed.Therefore,this work confirms the huge potentials of nonmagnetic bimetallic MOFs derivatives in EMW absorption applications.
摘要TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.
摘要In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (εr) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of εr = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.
基金Project(50802034) supported by the National Natural Science Foundation of ChinaProject(11A093) supported by the Key Project Foundation by the Education Department of Hunan Province,China
摘要TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content in TAs on the degradation rate.
摘要Polyaniline(PAn)sensitized nanocrystalline TiO2 composites(TiO2/PAn)were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue(MB).The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light(λ:190~800 nm),whereas pure TiO2 absorbed ultraviolet light only(λ〈380 nm).Under the irradiation of natural light,MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore,it could be easily separated from the solution by simple sedimentation.
摘要A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light (λ≥ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.
基金National Natural Science Foundations of China(Nos.51308079,51408073,51678080,51678081)
摘要Silica( SiO_2) based aerogel/xerogel materials have been received ever-growing attentions for versatile applications. However,the widespread applications are narrowed by the inert properties,fragile and brittle natureof silica materials and cumbersome preparation processes. In this paper,titania( TiO_2) was introduced into SiO_2 matrix to form photocatalytic hybrid gels. The TiO_2/SiO_2 composites were then reinforced by the impregnation of various fibrillary reinforcements,such as glass,mullite mineral and ceramic fibers. The properties of the composites were studied systematically in terms of fiberstability,microstructure,chemical interaction and thermal conductivity. The final xerogel composites displayed improved monolithic geometry,satisfied thermal conductivity(0. 09-0. 25 W·m-1·K-1) and optimized photocatalytic performance(85% removal of model pollutant of methyl orange( Mo)),which could be expected to be a feasible route to multi-functional building facades in the future.
基金supported by the National Basic Research Program of China (973 Program,2014CB239300)the National Natural Science Foundation of China (51572191)the Natural Science Foundation of Tianjin (13JCYBJC16600)~~
摘要We report the construction of a grapheneourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.
基金financially supported by the National Natural Science Foundation of China (No.51301118)the Projects of International Cooperation in Shanxi (No.2014081002)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (No.2013108)
摘要Cu2O/TiOa/Pt three-layer films were deposited on glass substrates using magnetron sputtering method. The surface morphology and the optical properties of the composite film were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet- visible spectroscopy (UV-Vis) and photoluminescence spectroscopy (PL). The photocatalytic activity of the samples was evaluated by the photocatalytic degradation of methyl orange (MO) aqueous solution under visible light irradiation. The results indicate that the Cu2O/TiO2/Pt composite films are made up of three layers which are Pt layer, anatase-TiO2 layer and Cu2O layer from bottom to top. The surface of the films is even and composed of regular-shaped spherical particles. The photocatalytic activity of the Cu2O/TiO2/Pt three-layer film is much higher than that of the Cu2O/TiO2 double-layer film. Such enhancement is ascribed to the presence of Pt layer, which further inhibits the photogenerated electron-hole recombination, prolongs the lifetime of the photogenerated carriers, increases the quantum efficiency and hence improves the photocatalytic activity of the film effectively.
基金supported by Ministry of New and Renewable Energy(MNRE)the Solar Energy Research Initiative(SERI),respectively.of Govt.of India
摘要We report a facile method for the fabrication of TiO2 nanofiber-nanoparticle composite (FP) via. simulta- neous electrospraying and electrospinning for dye-sensitized solar cell (DSC) applications. The loading of nanoparticles on the fibers is controlled by varying their feed rates during electrospinning. The FP composites having three different particle loading are prepared by the methodology and the FP with the highest particle loading (denoted as FP-3 in the manuscript) showed the best overall efficiency of 9.15% in comparison to the other compositions of the FP (FP-2, 8.15% and FP-1, Z51%, respectively) and nanofibers (F) and nanoparticles (P) separately (7.21 and 7.81, respectively). All the material systems are characterized by spec- troscopy, microscopy, surface area measurements and the devices are characterized by current-voltage (I-V), incident photon-to-current conversion efficiency (IPCE), electrochemical impedance measurements, etc. I-V, dye-loading and reflectance measurements throw light on the overall performance of the DSC devices.
摘要In the present work, composites of poly (methyl methacrylate)itanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their importance broad practical and medical applications. Thermal properties as well as X-ray diffraction analyses were employed to characterize the structure properties of such composite. The obtained results showed variations in the glass transition temperature (Tg), the melting temperature (Tm), shape and area of thermal peaks which were attributed to the different degrees of crystallinity and the existence of interactions between PMMA and TiO2 nanoparticle molecules. The XRD patterns showed sharpening of peaks at different concentrations of nano-TiO2 powder with PMMA. This indicated changes in the crystallinity/amorphosity ratio, and also suggested that the miscibility between the amorphous components of homo- polymers PMMA and nano-TiO2 powder is possible.The results showed that nano-TiO2 powder mix with PMMA can improve the thermal stability of the homo-polymer under investigation, lead- ing to interesting technological applications.
摘要Solid state NMR was successfully used to determine the proton spin-lattice relaxation time in the rotating frame (T1ρH) for systems based on polypropylene (PP) and PP with titanium dioxide (TiO2) organically modified or unmodified incorporated, in order to understand the molecular behavior of these systems. These techniques were employed in the samples organically modified and unmodified TiO2 to investigate the effect of organic modification on the dispersion and distribution of the particles in the PP matrix. The results were analyzed in terms of the effect of the particles organic modified or not according to the intermolecular interaction in the composites. According to the T1ρH values, all composites showed at least two domains: the short values were related to the rigid part, which included the crystalline and amorphous phase constricted in it, while the longer times were attributed to the amorphous region, which had higher molecular mobility compared to the rigid region of the materials. The increase in the relaxation time parameter in the composites compared to the pure PP was associated to the strong interaction between titanium dioxide particles and the polymer chains. This effect was more pronounced for the systems containing organically modified TiO2. According to the results, it could be inferred that intermolecular interaction occurred in the CH2 and CH groups, being more intense with CH2 groups. Finally, the solid state NMR techniques were able to evaluate the molecular dynamics of those systems.
摘要Using glucose and sucrose as the electron donors,the photocatalytic hydrogen evolution over Pt/TiO2 was investigated.Glucose and sucrose enhance notably the activity for hydrogen generation.The amounts of produced H2 increase almost proportionally to time within 5 h irradiation in the reaction systems of the two electron donors.The effect of the initial concentration of glucose and sucrose on the reaction rate is consistent with the Langmuir-Hinshelwood kinetic model.After 5 h irradiation,the COD(chemical oxygen demand) in the reaction system of glucose and in that of sucrose decrease by 33.2%,11.4% respectively.The effect of electron donors on the flat-band potential of conduction band of TiO2 electrode was investigated.The flat-band potential of conduction band of TiO2 electrode in the presence of the electron donors shifts negatively,and the shift in the presence of glucose is larger than that in the presence of sucrose due to glucose having a larger adsorption amount on TiO2.
基金Project(gf200901002)supported by the Open Research Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology of Nanchang Hangkong University,China
摘要ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr(OH)4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) spectrophotometer. The composite film shows a lamellar and porous structure which consists of anatase, futile and ZrO2 phases. The optical absorption edge of film is shifted to longer wavelength when ZrO2 is introduced to TiO2. Furthermore, the photocatalytic reaction rate constants of degradation of rhodamine B solution with ZrO2/TiO2 composite film and pure TiO2 film under ultraviolet irradiation are measured as 0.0442 and 0.0186 h 1, respectively.
基金financially supported by the National Natural Science Foundation of China(Nos.51871199 and 61534001)。
摘要Bi2(Te,Se)3 alloys are conventional commercial thermoelectric materials for solid-state refrigeration around room temperature.In recent years,much attention has been paid to various advanced thermoelectric composite materials due to the unique thermoelectric properties.In this work,Bi2Se3/TiO2 composites were prepared by hot pressing the plate-like Bi2Se3 powders coated in situ with hydrolyzed hytetabutyl-n-butyl titanate(TNBT),and therefore numerous TiO2 in micrometer size could be formed on the interface of Bi2Se3 grains.The carrier concentration in Bi2Se3 matrix is optimized subject to the addition of n-type semiconductor TiO2,contributing to a significant improved power factor.In the meantime,the lattice thermal conductivity is also suppressed due to the enhanced phonon scattering at Bi2Se3/TiO2 interface and amorphous TiO2 particles.As a consequence,a peak figure of merit(zT)of 0.41 is obtained at 525 K in Bi2Se3/15 mol%TiO2 composites,nearly 50%augment over the pristine Bi2Se3 binary compound.