Zinc oxide/low-density polyethylene （LDPE） nanocomposites were prepared for intrauterine devices. The change of Zn^2＋ release rates of nanocomposites （ doped with various mass fractions of zinc oxide nanoparticles...Zinc oxide/low-density polyethylene （LDPE） nanocomposites were prepared for intrauterine devices. The change of Zn^2＋ release rates of nanocomposites （ doped with various mass fractions of zinc oxide nanoparticles between 5wt% and 65 wt% ） for 264 days in a simulated uterine solution were investigated. The resuits show that initial burst phases are followed by near zero-order release phases. SEM technique was employed to observe the surface morphology of the 45wt% ZnO/ LDPE composite. Elements and phases on the surface of the nanocomposite after incubation were also analyzed by EDX and XRD respectively. The experimental results show that incrustation formation does not occur after incubation.展开更多
TiO_(2)-ZnO nanocomposites were synthesized by varying Ti:Zn molar ratio from 1:0.1(TZ-1:0.1)to 1:1(TZ-1:1).With increase in Zn content,from TZ-1:0.1 to TZ-1:0.2,anatase transformed to rutile phase.TZ-1:0.3,which cont...TiO_(2)-ZnO nanocomposites were synthesized by varying Ti:Zn molar ratio from 1:0.1(TZ-1:0.1)to 1:1(TZ-1:1).With increase in Zn content,from TZ-1:0.1 to TZ-1:0.2,anatase transformed to rutile phase.TZ-1:0.3,which contained a blend of phases,including rutile and anatase TiO_(2),ZnO,and zinc titanates,exhibited the narrowest bandgap(2.5±0.1 e V),and showed the highest photocatalytic activity.TZ-1:1 was predominated by zinc titanates.All the nanocomposites exhibited narrower bandgaps compared to pure TiO_(2)nanoparticles,facilitating visible light activity.This study was designed to explore whether a method targeting the removal of a specific crystalline phase(anatase)influenced the properties and photocatalytic activity of the nanocomposite.Selective dissolution not only removed anatase phase,but also led to significant loss of crystallinity,widened the bandgap,and adversely affected photocatalytic performance,in nanocomposites that contained>80%anatase phase(TZ-1:0.1 and TZ-1:0.2).However,in nanocomposites that contained less of anatase phase(TZ-1:0.3and TZ-1:1),the morphology,bandgap,crystallinity,and the extent of photocatalytic activity at the end of 240 min remained largely unaffected.Photocatalytic activity in TZ-1:0.3 and TZ-1:1 originated from a blend of phases comprising of less photocatalytically active phases,such as rutile TiO_(2),Zn TiO3,and Zn2TiO4,rather than from the anatase phase.The Ti:Zn molar ratio controlled the phases present in TiO_(2)-ZnO nanocomposites,which,in turn,controlled the physicochemical properties and visible light activity.Thus,in nanocomposites that contained a mix of several phases,the properties and photocatalytic activity were not dependent on anatase phase.展开更多
In this investigation, polymeric nanocomposite membranes（PNMs） were prepared via incorporating zinc oxide（ZnO） into poly（ether-block-amide）(PEBAX-1074) polymer matrix with different loadings. The neat membrane a...In this investigation, polymeric nanocomposite membranes（PNMs） were prepared via incorporating zinc oxide（ZnO） into poly（ether-block-amide）(PEBAX-1074) polymer matrix with different loadings. The neat membrane and nanocomposite membranes were prepared via solution casting and solution blending methods, respectively. The fabricated membranes were characterized by field emission scanning electron microscopy（FESEM） to survey cross-sectional morphologies and thermal gravimetric analysis（TGA）to study thermal stability. Fourier transform infrared（FT-IR） and X-ray diffraction（XRD） analyses were also employed to identify variations of the chemical bonds and crystal structure of the membranes, respectively. Permeation of pure gases, CO, CHand Nthrough the prepared neat and nanocomposite membranes was studied at pressures of 3–18 bar and temperature of 25 °C. The obtained results showed that the fabricated nanocomposite membranes exhibit better separation performance compared to the neat PEBAX membrane in terms of both permeability and selectivity. As an example, at temperature of 25 °C and pressure of 3 bar, COpermeability, ideal CO/CHand CO/Nselectivity values for the neat PEBAX membrane are 110.67 Barrer, 11.09 and 50.08, respectively, while those values are 152.27 Barrer,13.52 and 62.15 for PEBAX/ZnO nanocomposite membrane containing 8 wt% ZnO.展开更多
In this work, a series of Cu2O-Ag/ZnO, Cu2O/ZnO and Ag/ZnO nanocomposites with various compositions were prepared via a hydrothermal method followed by chemical modification, and their antibacterial performance was in...In this work, a series of Cu2O-Ag/ZnO, Cu2O/ZnO and Ag/ZnO nanocomposites with various compositions were prepared via a hydrothermal method followed by chemical modification, and their antibacterial performance was investigated in detail. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy results confirmed that 31 nm Cu20 and 30 nm Ag nanoparticles are well-dispersed on 202 nm ZnO grains to form a Cu2O/ZnO and Ag/ZnO heterojunction, respectively. The bi-heterojuction structure in the Cu20-Ag/ZnO provided a synergistic effect on antibacterial activity, and the(Cu2O)0.04Ag0.06ZnO0.9nanocomposites showed the highest antimicrobial activity of all samples with minimum inhibitory concentration and minimum bactericidal concentration against Escherichia coli and Staphylococcus aureus as low to 31.25 μg/mL, 250μg/mL, 125μg/mL and 500μg/mL, respectively. This is the first report of the antibacterial activities of Cu2O and Ag co-modified ZnO nanocomposites.展开更多
Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were inv...Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were investigated for different compositions of ZnO and SnO2 activated with Eu3＋ ions. The prepared samples were systematically characterized by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscopy for obtaining the structural information about the prepared materials. Diffuse reflectance （DR） UV-Vis spectrometer and photoluminescence （PL） spectroscopy technique were employed for studying the optical properties of prepared materials. XRD results confirmed the presence of both phases, hexagonal ZnO as well as tetragonal SnO2 simultaneously and further using Debye Scherrer＇s and Hall-Williamson relations, crystallite size were estimated and it was found to be in the range of 8-14 nm. The FTIR studies revealed the presence of different stretching and bending modes of Zn-O and Sn-O with an additional stretching and bending vibration of absorbed water （O-H） molecules. FESEM images suggested that the particle size lied in the range of 50 to 70 nm, which were almost spherical in shapes. A long range multi colour emission from blue to red region was observed for the 320 nm excitation wavelength. The observed emission involved sharp emission due to 5D0→7F1 transition that corresponded to the magnetic dipole transition. The study showed that the Eu3＋ doped nanocomposite was more suitable material than singly Eu3＋ doped ZnO and Eu3＋ doped SnO2 with enhanced opto-eleetronic and luminescence properties and potential applications in display devices.展开更多
ZnO–TiO_(2) thin films containing 0.5 mol%,1.0 mol%,and 5.0 mol%ZnO were synthesized by oxidative solidphase pyrolysis.The materials contained anatase and rutile phases with particle size of 6–13 nm,as confirmed usi...ZnO–TiO_(2) thin films containing 0.5 mol%,1.0 mol%,and 5.0 mol%ZnO were synthesized by oxidative solidphase pyrolysis.The materials contained anatase and rutile phases with particle size of 6–13 nm,as confirmed using X-ray phase analysis and scanning electron microscopy.When a certain number of ZnO crystallites appeared in the TiO_(2) film structure in the temperature range of room temperature to 220℃,a two-level response of the film resistance was observed,differing by approximately 10%,as obtained by electrophysical measurements.The two-level response correlates with the formation of two donor energy levels of 0.28 and 0.33 eV in the band structure of the ZnO–TiO_(2) films.The donor level with a higher activation energy corresponded to the Ti vacancy(V−Ti),and that with a lower activation energy corresponded to the Zn vacancy(V−Zn).Two levels of gas-sensitive properties were noted for 0.5ZnO–TiO_(2),1ZnO–TiO_(2),and 5ZnO–TiO_(2) under the influence of 50 ppm NO_(2) at 250℃.Such two-level responses can be ascribed to the pinning of the Fermi level on ZnO and TiO_(2) nanocrystallites.The mechanism of the beak-shaped and two-level responses of sensors based on composite nanomaterials when exposed to various gases was elucidated.展开更多
文摘Zinc oxide/low-density polyethylene （LDPE） nanocomposites were prepared for intrauterine devices. The change of Zn^2＋ release rates of nanocomposites （ doped with various mass fractions of zinc oxide nanoparticles between 5wt% and 65 wt% ） for 264 days in a simulated uterine solution were investigated. The resuits show that initial burst phases are followed by near zero-order release phases. SEM technique was employed to observe the surface morphology of the 45wt% ZnO/ LDPE composite. Elements and phases on the surface of the nanocomposite after incubation were also analyzed by EDX and XRD respectively. The experimental results show that incrustation formation does not occur after incubation.
基金provided by Department of Science and Technology,New Delhi,India,under the Water Technology Initiative(WTI)scheme(Project code:DST/TM/WTI/2K15/101(G)).
文摘TiO_(2)-ZnO nanocomposites were synthesized by varying Ti:Zn molar ratio from 1:0.1(TZ-1:0.1)to 1:1(TZ-1:1).With increase in Zn content,from TZ-1:0.1 to TZ-1:0.2,anatase transformed to rutile phase.TZ-1:0.3,which contained a blend of phases,including rutile and anatase TiO_(2),ZnO,and zinc titanates,exhibited the narrowest bandgap(2.5±0.1 e V),and showed the highest photocatalytic activity.TZ-1:1 was predominated by zinc titanates.All the nanocomposites exhibited narrower bandgaps compared to pure TiO_(2)nanoparticles,facilitating visible light activity.This study was designed to explore whether a method targeting the removal of a specific crystalline phase(anatase)influenced the properties and photocatalytic activity of the nanocomposite.Selective dissolution not only removed anatase phase,but also led to significant loss of crystallinity,widened the bandgap,and adversely affected photocatalytic performance,in nanocomposites that contained>80%anatase phase(TZ-1:0.1 and TZ-1:0.2).However,in nanocomposites that contained less of anatase phase(TZ-1:0.3and TZ-1:1),the morphology,bandgap,crystallinity,and the extent of photocatalytic activity at the end of 240 min remained largely unaffected.Photocatalytic activity in TZ-1:0.3 and TZ-1:1 originated from a blend of phases comprising of less photocatalytically active phases,such as rutile TiO_(2),Zn TiO3,and Zn2TiO4,rather than from the anatase phase.The Ti:Zn molar ratio controlled the phases present in TiO_(2)-ZnO nanocomposites,which,in turn,controlled the physicochemical properties and visible light activity.Thus,in nanocomposites that contained a mix of several phases,the properties and photocatalytic activity were not dependent on anatase phase.
文摘In this investigation, polymeric nanocomposite membranes（PNMs） were prepared via incorporating zinc oxide（ZnO） into poly（ether-block-amide）(PEBAX-1074) polymer matrix with different loadings. The neat membrane and nanocomposite membranes were prepared via solution casting and solution blending methods, respectively. The fabricated membranes were characterized by field emission scanning electron microscopy（FESEM） to survey cross-sectional morphologies and thermal gravimetric analysis（TGA）to study thermal stability. Fourier transform infrared（FT-IR） and X-ray diffraction（XRD） analyses were also employed to identify variations of the chemical bonds and crystal structure of the membranes, respectively. Permeation of pure gases, CO, CHand Nthrough the prepared neat and nanocomposite membranes was studied at pressures of 3–18 bar and temperature of 25 °C. The obtained results showed that the fabricated nanocomposite membranes exhibit better separation performance compared to the neat PEBAX membrane in terms of both permeability and selectivity. As an example, at temperature of 25 °C and pressure of 3 bar, COpermeability, ideal CO/CHand CO/Nselectivity values for the neat PEBAX membrane are 110.67 Barrer, 11.09 and 50.08, respectively, while those values are 152.27 Barrer,13.52 and 62.15 for PEBAX/ZnO nanocomposite membrane containing 8 wt% ZnO.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.51677120 and 51207093)the Shenzhen Government Fund(Grant Nos.JCYJ20160422102919963)the Shenzhen Key Laboratory of Special Functional Materials(Grant Nos.T201502)
文摘In this work, a series of Cu2O-Ag/ZnO, Cu2O/ZnO and Ag/ZnO nanocomposites with various compositions were prepared via a hydrothermal method followed by chemical modification, and their antibacterial performance was investigated in detail. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy results confirmed that 31 nm Cu20 and 30 nm Ag nanoparticles are well-dispersed on 202 nm ZnO grains to form a Cu2O/ZnO and Ag/ZnO heterojunction, respectively. The bi-heterojuction structure in the Cu20-Ag/ZnO provided a synergistic effect on antibacterial activity, and the(Cu2O)0.04Ag0.06ZnO0.9nanocomposites showed the highest antimicrobial activity of all samples with minimum inhibitory concentration and minimum bactericidal concentration against Escherichia coli and Staphylococcus aureus as low to 31.25 μg/mL, 250μg/mL, 125μg/mL and 500μg/mL, respectively. This is the first report of the antibacterial activities of Cu2O and Ag co-modified ZnO nanocomposites.
基金supported by ISM research scholars funding by Government of India
文摘Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were investigated for different compositions of ZnO and SnO2 activated with Eu3＋ ions. The prepared samples were systematically characterized by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscopy for obtaining the structural information about the prepared materials. Diffuse reflectance （DR） UV-Vis spectrometer and photoluminescence （PL） spectroscopy technique were employed for studying the optical properties of prepared materials. XRD results confirmed the presence of both phases, hexagonal ZnO as well as tetragonal SnO2 simultaneously and further using Debye Scherrer＇s and Hall-Williamson relations, crystallite size were estimated and it was found to be in the range of 8-14 nm. The FTIR studies revealed the presence of different stretching and bending modes of Zn-O and Sn-O with an additional stretching and bending vibration of absorbed water （O-H） molecules. FESEM images suggested that the particle size lied in the range of 50 to 70 nm, which were almost spherical in shapes. A long range multi colour emission from blue to red region was observed for the 320 nm excitation wavelength. The observed emission involved sharp emission due to 5D0→7F1 transition that corresponded to the magnetic dipole transition. The study showed that the Eu3＋ doped nanocomposite was more suitable material than singly Eu3＋ doped ZnO and Eu3＋ doped SnO2 with enhanced opto-eleetronic and luminescence properties and potential applications in display devices.
基金supported by the Russian Science Foundation 24-29-00203(https://rscf.ru/project/24-29-00203/)at the Southern Federal University.
文摘ZnO–TiO_(2) thin films containing 0.5 mol%,1.0 mol%,and 5.0 mol%ZnO were synthesized by oxidative solidphase pyrolysis.The materials contained anatase and rutile phases with particle size of 6–13 nm,as confirmed using X-ray phase analysis and scanning electron microscopy.When a certain number of ZnO crystallites appeared in the TiO_(2) film structure in the temperature range of room temperature to 220℃,a two-level response of the film resistance was observed,differing by approximately 10%,as obtained by electrophysical measurements.The two-level response correlates with the formation of two donor energy levels of 0.28 and 0.33 eV in the band structure of the ZnO–TiO_(2) films.The donor level with a higher activation energy corresponded to the Ti vacancy(V−Ti),and that with a lower activation energy corresponded to the Zn vacancy(V−Zn).Two levels of gas-sensitive properties were noted for 0.5ZnO–TiO_(2),1ZnO–TiO_(2),and 5ZnO–TiO_(2) under the influence of 50 ppm NO_(2) at 250℃.Such two-level responses can be ascribed to the pinning of the Fermi level on ZnO and TiO_(2) nanocrystallites.The mechanism of the beak-shaped and two-level responses of sensors based on composite nanomaterials when exposed to various gases was elucidated.
