Transparent zinc oxide thin film transistors （ZnO-TFTs） with bottom-gate and top-gate structures were constructed on 50mm silica glass substrates. The ZnO films were deposited by RF magnetron sputtering and SiO2 fil...Transparent zinc oxide thin film transistors （ZnO-TFTs） with bottom-gate and top-gate structures were constructed on 50mm silica glass substrates. The ZnO films were deposited by RF magnetron sputtering and SiO2 films served as the gate insulator layer. We found that the ZnO-TFTs with bottom-gate structure have better electrical performance than those with top-gate structure. The bottom-gate ZnO-TFTs operate as an n-channel enhancement mode, which have clear pinch off and saturation characteristics. The field effect mobility, threshold voltage, and the current on/off ratio were determined to be 18.4cm^2/（V ·s）, - 0. 5V and 10^4 , respectively. Meanwhile, the top-gate ZnO-TFTs exhibit n-chan- nel depletion mode operation and no saturation characteristics were detected. The electrical difference of the devices may be due to the different character of the interface between the channel and insulator layers. The two transistors types have high transparency in the visible light region.展开更多
AIM： This study evaluated colorectal mucosal histamine release in response to blinded food challenge-positive and-negative food antigens as a new diagnostic procedure. METHODS： 19 patients suffering from gastrointes...AIM： This study evaluated colorectal mucosal histamine release in response to blinded food challenge-positive and-negative food antigens as a new diagnostic procedure. METHODS： 19 patients suffering from gastrointestinally mediated allergy confirmed by blinded oral provocation were investigated on grounds of their case history, skin prick tests, serum IgE detection and colorectal mucosal histamine release by ex vivo mucosa oxygenation. Intact tissue particles were incubated/stimulated in an oxygenated culture with different food antigens for 30 min. Specimens challenged with anti-human immunoglobulin E and without any stimulus served as positive and negative controls, respectively. Mucosal histamine release （% of total biopsy histamine content） was considered successful （positive）, when the rate of histamine release from biopsies in response to antigens reached more than twice that of the spontaneous release. Histamine measurement was performed by radioimmunoassay. RESULTS： The median （range） of spontaneous histamine release from colorectal mucosa was found to be 3.2 （0.1%-25.8%） of the total biopsy histamine content. Food antigens tolerated by oral provocation did not elicit mast cell degranulation 3.4 （0.4%-20.7%, P=0.4）, while anti-IgE and causative food allergens induced a significant histamine release of 5.4 （1.1%-25.6%, P = 0.04） and 8.1 （1.5%-57.9%, P = 0.008）, respectively. 12 of 19 patients （63.1%） showed positive colorectal mucosal histamine release in accordance with the blinded oral challenge responding to the same antigen （s）, while the specificity of the functional histamine release to accurately recognise tolerated foodstuffs was found to be 78.6%. In comparison with the outcome of blinded food challenge tests, sensitivity and specificity of history （30.8% and 57.1%）, skin tests （47.4% and 78.6%） or antigen-specific serum IgE determinations （57.9% and 50%） were found to be of lower diagnostic accuracy in gastrointestinally mediated allergy. CONCLUSION： Functional testing of the reactivity of colorectal mucosa upon antigenic stimulation in patients with gastrointestinally mediated allergy is of higher diagnostic efficacy.展开更多
VO 2 thin films with good switching properties were prepared by controlling the annealing time and the annealing temperature in a vacuum system. The structural, optical and electrical properties of the samples were ch...VO 2 thin films with good switching properties were prepared by controlling the annealing time and the annealing temperature in a vacuum system. The structural, optical and electrical properties of the samples were characterized by using XRD、XPS、UV-VIS and electrical measurements. The switching parameters of VO 2 thin film were investigated too. The results indicate that before and after phase transition the resistance of VO 2 thin films changes about three orders of magnitude, the variation of film transmittance of 40 % has been carried out with the absorptivity switching velocity of about 0.260 7 /min at 900 nm . The structural property of samples has been improved but the phase-transition properties have been decreased by increasing the annealing time and annealing temperature. The valence of V ions and the structure of samples have great effect on phase transition properties of VO 2 thin films. Discussion on the effects of annealing time and annealing temperature on the phase-transition temperature and hysteresis width shows that the best reasonable annealing time and annealing temperature can be achieved.展开更多
A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnOz thin films was proposed with current density of 8 mA/cm^2...A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnOz thin films was proposed with current density of 8 mA/cm^2, the time of deposition of 120 min, the concentration of tin dichloride of 0.02 mol/L and the concentration of dissociated acid of 0. 03 mol/L. The phase identification, microstructure and morphology of the thin films were investigated by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectra,scanning electron microscopy and transmission electron microscopy. The as-deposited thin film was composed of SnO2·xH2O was obtained by drying at room temperature. Nanocrystalline SnO2 thin film having tetragonal structure with average grain size in the range of 8 to 20 nm and porous, uniform surface was obtained by heat-treating the as-deposited film at 400 ℃ for 2 h. Electrochemical characterization shows that SnO2 film can deliver a discharge capacity of 798 mAh/g and the SnO2 film with smooth surface and annealed at 400 ℃ for 2 h has better cycle performance than that with rough surface and annealed at 150℃ for 10 h.展开更多
[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied...[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.展开更多
The effects of Pb^2+concentration,current density,deposition time and temperature on Pb deposit structure were investigated.In lower Pb^2+concentration(~0.15 mol/L),carambola-like 3D-Pb structure was constructed,while...The effects of Pb^2+concentration,current density,deposition time and temperature on Pb deposit structure were investigated.In lower Pb^2+concentration(~0.15 mol/L),carambola-like 3D-Pb structure was constructed,while in higher Pb2+concentration(≥0.30 mol/L),Pb deposits exhibited pyramid-like structure.Furthermore,the oxide layer and anodic potential of carambola-shaped 3D-Pb(Cara-Pb)and pyramid-shaped 3D-Pb(Pyra-Pb)anodes were investigated and compared with those of fresh Pb anode.After 72 h galvanostatic electrolysis(50 mA/cm2)in 160 g/L H2SO4 solution,the oxide layer on Pyra-Pb was much thicker than that on Cara-Pb and Pb anodes,which remarkably relieved intercrystalline corrosion of the metallic substrate.Additionally,the oxide layer on Pyra-Pb anode presented a larger surface area and higher PbO2 content.Hence,Pyra-Pb anode showed a 40 m V lower anodic potential compared to Cara-Pb and Pb anodes.In sum,Pyra-Pb anode had a potential to decrease energy consumption and prolong the life span of traditional Pb anode.展开更多
The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerim...The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.展开更多
In this study,a high-purity In_(2)Ga_(2)ZnO_(7) ceramic target was used to deposit indium gallium zinc oxide(IGZO)films by RF magnetron sputtering technology.The microstructure,growth state,optical and electrical prop...In this study,a high-purity In_(2)Ga_(2)ZnO_(7) ceramic target was used to deposit indium gallium zinc oxide(IGZO)films by RF magnetron sputtering technology.The microstructure,growth state,optical and electrical properties of the IGZO films were studied.The results showed that the surface of the IGZO film was uniform and smooth at room temperature.As the substrate temperature increased,the surface roughness of the film gradually increased.From room temperature to 300℃,all the films maintained amorphous phase and good thermal stabilities.Moreover,the transmission in the visible region decreased from 91.93%to 91.08%,and the band gap slightly decreased from 3.79 to 3.76 eV.The characterization of the film via atomic force microscope(AFM)and X-ray photoelectron spectroscopy(XPS)demonstrated that the film prepared at room temperature exhibited the lowest surface roughness and the largest content of oxygen vacancies.With the rise in temperature,the non-homogeneous particle distribution,increase in the surface roughness,and reduction in the number of oxygen vacancies resulted in lower performance of theα-IGZO film.Comprehensive analysis showed that the best optical and electrical properties can be obtained by depositing IGZO films at room temperature,which indicates their potential applications in flexible substrates.展开更多
Semiconductor-type TiO2 oxygen sensing thin films were synthesized using tetrabutyl titanate （Ti （OBu）4） as precursor and diethanolamine （DEA） as complexing agent by the sol-get process. The porous and oxygen se...Semiconductor-type TiO2 oxygen sensing thin films were synthesized using tetrabutyl titanate （Ti （OBu）4） as precursor and diethanolamine （DEA） as complexing agent by the sol-get process. The porous and oxygen sensing TiO2 films were obtained by the addition of polyethylene glycol （PEG）. The micrographs of scanning electron microscope （SEM） show that the pores of the sample about 400-600 nm in size with PEG（2 000 g/mol） are larger than those about 300 nm in size with PEG（ 1 000 g/mol）, while the density of pores is lower. The results also indicate that increasing the content of PEG properly is beneficial to the formation of porous structure. With the increasing content of PEG from 0 g to 2.5 g, the oxygen sensitivity increases from 330 to more than 1 000 at 800 ℃, from 170 to more than 1 000 at 900℃, and the response time to O2 and H2 are about 1.5 s and less than 1s, respectively.展开更多
Owing to both of its high carrier concentration and large band gap, ZnO:Al (ZAO) films which is an n-type degenerate semiconductor, exhibits low resistance and high transmittance in the visible range. This work studie...Owing to both of its high carrier concentration and large band gap, ZnO:Al (ZAO) films which is an n-type degenerate semiconductor, exhibits low resistance and high transmittance in the visible range. This work studies the crystal structure, optical and electrical properties and preparation methods of ZAO films, and discusses the existing problems and application prospective of ZAO films.展开更多
The complete restoration of a perfect carbon lattice has been a central issue in the research on graphene derived from graphite oxide since this preparation route was first proposed several years ago, but such a goal ...The complete restoration of a perfect carbon lattice has been a central issue in the research on graphene derived from graphite oxide since this preparation route was first proposed several years ago, but such a goal has so far remained elusive. Here, we demonstrate that the highly defective structure of reduced graphene oxide sheets assembled into free-standing, paper-like films can be fully repaired by means of high temperature annealing （graphitization）. Characterization of the films by X-ray photoelectron and Raman spectroscopy, X-ray diffraction and scanning tunneling microscopy indicated that the main stages in the transformation of the films were （i） complete removal of oxygen functional groups and generation of atomic vacancies （up to 1,500 ~C）, and （ii） vacancy annihilation and coalescence of adjacent overlapping sheets to yield continuous polycrystalline layers （1,800-2,700 ~C） similar to those of highly oriented graphites. The prevailing type of defect in the polycrystalline layers were the grain boundaries separating neighboring domains, which were typically a few hundred nanometers in lateral size, exhibited long-range graphitic order and were virtually free of even atomic-sized defects. The electrical conductivity of the annealed films was as high as 577,000 S-m-1, which is by far the largest value reported to date for any material derived from graphene oxide, and strategies for further improvement without the need to resort to higher annealing temperatures are suggested. Overall, this work opens the prospect of truly achieving a complete restoration of the carbon lattice in graphene oxide materials.展开更多
Here, we report a study of ion transport across graphene oxide （GO） membranes of various thicknesses, made by vacuum filtration of GO aqueous solutions. The diffusive transport rates of two charge-equivalent rutheni...Here, we report a study of ion transport across graphene oxide （GO） membranes of various thicknesses, made by vacuum filtration of GO aqueous solutions. The diffusive transport rates of two charge-equivalent ruthenium complex ions Ru（bpy）3^2＋ and Ru（phen）32% with a sub-angstrom size difference, are distinguishable through GO membranes and their ratio can be a unique tool for probing the transport-relevant pore structures. Pore and slit-dominant hindered diffusion models are presented and correlated to experimental results. Our analysis suggests that ion transport is mostly facilitated by large pores （larger than 1.75 nm in diameter） in the relatively thin GO membranes, while slits formed by GO stacking （less than 1.42 nm in width） become dominant only in thick membranes. By grafting PEG molecules to the lateral plane of GO sheets, membranes with enlarged interlayer spacing were engineered, which showed drastically increased ion transport rates and lower distinction among the two ruthenium complex ions, consistent with the prediction by the slit-dominant steric hindered diffusion model.展开更多
Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide （GO） and completely reduced GO （...Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide （GO） and completely reduced GO （rGO） membranes suffer florn low water permeance because of the lack of pristine graphitic sp2 domains and very small interlayer spacing, respectively. In this work, we studied the influence of reduction degree on the structure and separation pertornrance of rGO membranes, tt was found that weak reduction retains the good dispersion and hydrophilicity of GO nanosheets. More importantly, it increases the number of pristine graphitic sp2 domains in rGO nanosheets while keeping the large interlayer spacing of the GO membranes in most regions at the same time. The resultant mernbranes show a high water permeance of 56.3 L m^-2 h^ -1 bar^ -1, which is about 4 times and over 10^4 times larger tban those of the GO and completely reduced rGO membranes, respectively, and high rejection over 95700 for various dyes. Furthermore, they show better structure stability and more superior separation perfor- mance than GO membranes in acid and alkali environments.展开更多
Photoelectrodes with a specific structure and composition have been proposed for improving the efficiency of solar water splitting. Here, a novel multijunction structure was fabricated, with Si nanowires as cores, ZnI...Photoelectrodes with a specific structure and composition have been proposed for improving the efficiency of solar water splitting. Here, a novel multijunction structure was fabricated, with Si nanowires as cores, ZnIn2S4 nanosheets as branches, and TiO2 films as sandwiched layers. This junction exhibited a superior photoelectrochemical performance with a maximum photoconversion efficiency of 0.51%, which is 795 and 64 times higher than that of a bare Si wafer and nanowires, respectively. The large enhancement was attributed to the effective electron-hole separation and fast excited carrier transport within the multijunctions resulting from their favorable energy band alignments with water redox potentials, and to the enlarged contact area for facilitating the electron transfer at the multijunction/electrolyte interface.展开更多
An inkjet-printed graphene film is of great importance for next-generation flexible, low cost and high performance electronic devices. However, due to the limitation of the inkjet printing process, the electrical cond...An inkjet-printed graphene film is of great importance for next-generation flexible, low cost and high performance electronic devices. However, due to the limitation of the inkjet printing process, the electrical conductivity of inkjet-printed graphene films is limited to N10 S＇cm-1, and achieving a high conductivity of the printed graphene films remains a big challenge. Here, we develop a ＂weak oxidation- vigorous exfoliation＂ strategy to tailor graphene oxide （GO） for meeting all the requirements of highly conductive inkjet-printed graphene films, including a more intact carbon plane and suitable size. The -conjugated structure of the resulting graphene has been restored to a high degree, and its printed films show an ultrahigh conductivity of -420 S-cm-I, which is tens of times higher than previously reported results, suggesting that, aside from developing a highly efficient reduction method, tuning the GO structure could be an alternative way to produce high quality graphene sheets. Using inkjet-printed graphene patterns as source/drain/gate electrodes, and semiconducting single-walled carbon nanotubes （SWCNTs） as channels, we fabricated an all-carbon field effect transistor which shows excellent performance （an on/off ratio of -104 and a mobility of -8 cm2＂V-l＇s-1） compared to previously reported CNT-based transistors, promising the use of nanocarbon materials, graphene and SWCNTs in printed electronics, especially where high performance and flexibility are needed.展开更多
文摘Transparent zinc oxide thin film transistors （ZnO-TFTs） with bottom-gate and top-gate structures were constructed on 50mm silica glass substrates. The ZnO films were deposited by RF magnetron sputtering and SiO2 films served as the gate insulator layer. We found that the ZnO-TFTs with bottom-gate structure have better electrical performance than those with top-gate structure. The bottom-gate ZnO-TFTs operate as an n-channel enhancement mode, which have clear pinch off and saturation characteristics. The field effect mobility, threshold voltage, and the current on/off ratio were determined to be 18.4cm^2/（V ·s）, - 0. 5V and 10^4 , respectively. Meanwhile, the top-gate ZnO-TFTs exhibit n-chan- nel depletion mode operation and no saturation characteristics were detected. The electrical difference of the devices may be due to the different character of the interface between the channel and insulator layers. The two transistors types have high transparency in the visible light region.
文摘AIM： This study evaluated colorectal mucosal histamine release in response to blinded food challenge-positive and-negative food antigens as a new diagnostic procedure. METHODS： 19 patients suffering from gastrointestinally mediated allergy confirmed by blinded oral provocation were investigated on grounds of their case history, skin prick tests, serum IgE detection and colorectal mucosal histamine release by ex vivo mucosa oxygenation. Intact tissue particles were incubated/stimulated in an oxygenated culture with different food antigens for 30 min. Specimens challenged with anti-human immunoglobulin E and without any stimulus served as positive and negative controls, respectively. Mucosal histamine release （% of total biopsy histamine content） was considered successful （positive）, when the rate of histamine release from biopsies in response to antigens reached more than twice that of the spontaneous release. Histamine measurement was performed by radioimmunoassay. RESULTS： The median （range） of spontaneous histamine release from colorectal mucosa was found to be 3.2 （0.1%-25.8%） of the total biopsy histamine content. Food antigens tolerated by oral provocation did not elicit mast cell degranulation 3.4 （0.4%-20.7%, P=0.4）, while anti-IgE and causative food allergens induced a significant histamine release of 5.4 （1.1%-25.6%, P = 0.04） and 8.1 （1.5%-57.9%, P = 0.008）, respectively. 12 of 19 patients （63.1%） showed positive colorectal mucosal histamine release in accordance with the blinded oral challenge responding to the same antigen （s）, while the specificity of the functional histamine release to accurately recognise tolerated foodstuffs was found to be 78.6%. In comparison with the outcome of blinded food challenge tests, sensitivity and specificity of history （30.8% and 57.1%）, skin tests （47.4% and 78.6%） or antigen-specific serum IgE determinations （57.9% and 50%） were found to be of lower diagnostic accuracy in gastrointestinally mediated allergy. CONCLUSION： Functional testing of the reactivity of colorectal mucosa upon antigenic stimulation in patients with gastrointestinally mediated allergy is of higher diagnostic efficacy.
文摘VO 2 thin films with good switching properties were prepared by controlling the annealing time and the annealing temperature in a vacuum system. The structural, optical and electrical properties of the samples were characterized by using XRD、XPS、UV-VIS and electrical measurements. The switching parameters of VO 2 thin film were investigated too. The results indicate that before and after phase transition the resistance of VO 2 thin films changes about three orders of magnitude, the variation of film transmittance of 40 % has been carried out with the absorptivity switching velocity of about 0.260 7 /min at 900 nm . The structural property of samples has been improved but the phase-transition properties have been decreased by increasing the annealing time and annealing temperature. The valence of V ions and the structure of samples have great effect on phase transition properties of VO 2 thin films. Discussion on the effects of annealing time and annealing temperature on the phase-transition temperature and hysteresis width shows that the best reasonable annealing time and annealing temperature can be achieved.
文摘A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnOz thin films was proposed with current density of 8 mA/cm^2, the time of deposition of 120 min, the concentration of tin dichloride of 0.02 mol/L and the concentration of dissociated acid of 0. 03 mol/L. The phase identification, microstructure and morphology of the thin films were investigated by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectra,scanning electron microscopy and transmission electron microscopy. The as-deposited thin film was composed of SnO2·xH2O was obtained by drying at room temperature. Nanocrystalline SnO2 thin film having tetragonal structure with average grain size in the range of 8 to 20 nm and porous, uniform surface was obtained by heat-treating the as-deposited film at 400 ℃ for 2 h. Electrochemical characterization shows that SnO2 film can deliver a discharge capacity of 798 mAh/g and the SnO2 film with smooth surface and annealed at 400 ℃ for 2 h has better cycle performance than that with rough surface and annealed at 150℃ for 10 h.
基金Project(10574085) supported by the National Natural Science Foundation of ChinaProject(207020) supported by the Science Technology Key Project of the Ministry of Education, China
文摘[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.
基金Project(51704130)supported by the National Natural Science Foundation of ChinaProject(GK-201905)supported by the Research Fund of State Key Laboratory of Rare Metals Separation and Comprehensive Utilization,ChinaProject(jxxjbs16026)supported by the Doctoral Scientific Research Foundation of Jiangxi University of Science and Technology,China
文摘The effects of Pb^2+concentration,current density,deposition time and temperature on Pb deposit structure were investigated.In lower Pb^2+concentration(~0.15 mol/L),carambola-like 3D-Pb structure was constructed,while in higher Pb2+concentration(≥0.30 mol/L),Pb deposits exhibited pyramid-like structure.Furthermore,the oxide layer and anodic potential of carambola-shaped 3D-Pb(Cara-Pb)and pyramid-shaped 3D-Pb(Pyra-Pb)anodes were investigated and compared with those of fresh Pb anode.After 72 h galvanostatic electrolysis(50 mA/cm2)in 160 g/L H2SO4 solution,the oxide layer on Pyra-Pb was much thicker than that on Cara-Pb and Pb anodes,which remarkably relieved intercrystalline corrosion of the metallic substrate.Additionally,the oxide layer on Pyra-Pb anode presented a larger surface area and higher PbO2 content.Hence,Pyra-Pb anode showed a 40 m V lower anodic potential compared to Cara-Pb and Pb anodes.In sum,Pyra-Pb anode had a potential to decrease energy consumption and prolong the life span of traditional Pb anode.
基金Supported by the National-Basic Research Program of China （2003CB615707） and the National Natural Science Foundation of China （20636020）.
文摘The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.
基金Project(2018M632797)supported by the Postdoctoral Science Foundation of ChinaProject(52004253)supported by the National Natural Science Foundation of China。
文摘In this study,a high-purity In_(2)Ga_(2)ZnO_(7) ceramic target was used to deposit indium gallium zinc oxide(IGZO)films by RF magnetron sputtering technology.The microstructure,growth state,optical and electrical properties of the IGZO films were studied.The results showed that the surface of the IGZO film was uniform and smooth at room temperature.As the substrate temperature increased,the surface roughness of the film gradually increased.From room temperature to 300℃,all the films maintained amorphous phase and good thermal stabilities.Moreover,the transmission in the visible region decreased from 91.93%to 91.08%,and the band gap slightly decreased from 3.79 to 3.76 eV.The characterization of the film via atomic force microscope(AFM)and X-ray photoelectron spectroscopy(XPS)demonstrated that the film prepared at room temperature exhibited the lowest surface roughness and the largest content of oxygen vacancies.With the rise in temperature,the non-homogeneous particle distribution,increase in the surface roughness,and reduction in the number of oxygen vacancies resulted in lower performance of theα-IGZO film.Comprehensive analysis showed that the best optical and electrical properties can be obtained by depositing IGZO films at room temperature,which indicates their potential applications in flexible substrates.
基金National Natural Science Foundation of China (No 59995520)
文摘Semiconductor-type TiO2 oxygen sensing thin films were synthesized using tetrabutyl titanate （Ti （OBu）4） as precursor and diethanolamine （DEA） as complexing agent by the sol-get process. The porous and oxygen sensing TiO2 films were obtained by the addition of polyethylene glycol （PEG）. The micrographs of scanning electron microscope （SEM） show that the pores of the sample about 400-600 nm in size with PEG（2 000 g/mol） are larger than those about 300 nm in size with PEG（ 1 000 g/mol）, while the density of pores is lower. The results also indicate that increasing the content of PEG properly is beneficial to the formation of porous structure. With the increasing content of PEG from 0 g to 2.5 g, the oxygen sensitivity increases from 330 to more than 1 000 at 800 ℃, from 170 to more than 1 000 at 900℃, and the response time to O2 and H2 are about 1.5 s and less than 1s, respectively.
基金Funded by the foundation for key projects in 2000 of the Science and Technology Committee of Chongqing China (No.2000-6214).
文摘Owing to both of its high carrier concentration and large band gap, ZnO:Al (ZAO) films which is an n-type degenerate semiconductor, exhibits low resistance and high transmittance in the visible range. This work studies the crystal structure, optical and electrical properties and preparation methods of ZAO films, and discusses the existing problems and application prospective of ZAO films.
文摘The complete restoration of a perfect carbon lattice has been a central issue in the research on graphene derived from graphite oxide since this preparation route was first proposed several years ago, but such a goal has so far remained elusive. Here, we demonstrate that the highly defective structure of reduced graphene oxide sheets assembled into free-standing, paper-like films can be fully repaired by means of high temperature annealing （graphitization）. Characterization of the films by X-ray photoelectron and Raman spectroscopy, X-ray diffraction and scanning tunneling microscopy indicated that the main stages in the transformation of the films were （i） complete removal of oxygen functional groups and generation of atomic vacancies （up to 1,500 ~C）, and （ii） vacancy annihilation and coalescence of adjacent overlapping sheets to yield continuous polycrystalline layers （1,800-2,700 ~C） similar to those of highly oriented graphites. The prevailing type of defect in the polycrystalline layers were the grain boundaries separating neighboring domains, which were typically a few hundred nanometers in lateral size, exhibited long-range graphitic order and were virtually free of even atomic-sized defects. The electrical conductivity of the annealed films was as high as 577,000 S-m-1, which is by far the largest value reported to date for any material derived from graphene oxide, and strategies for further improvement without the need to resort to higher annealing temperatures are suggested. Overall, this work opens the prospect of truly achieving a complete restoration of the carbon lattice in graphene oxide materials.
文摘Here, we report a study of ion transport across graphene oxide （GO） membranes of various thicknesses, made by vacuum filtration of GO aqueous solutions. The diffusive transport rates of two charge-equivalent ruthenium complex ions Ru（bpy）3^2＋ and Ru（phen）32% with a sub-angstrom size difference, are distinguishable through GO membranes and their ratio can be a unique tool for probing the transport-relevant pore structures. Pore and slit-dominant hindered diffusion models are presented and correlated to experimental results. Our analysis suggests that ion transport is mostly facilitated by large pores （larger than 1.75 nm in diameter） in the relatively thin GO membranes, while slits formed by GO stacking （less than 1.42 nm in width） become dominant only in thick membranes. By grafting PEG molecules to the lateral plane of GO sheets, membranes with enlarged interlayer spacing were engineered, which showed drastically increased ion transport rates and lower distinction among the two ruthenium complex ions, consistent with the prediction by the slit-dominant steric hindered diffusion model.
基金supported by the National Key Research and Development Program of China(2016YFA0200101)the National Natural Science Foundation of China(51325205,51290273,and51521091)Chinese Academy of Sciences(KGZD-EW-303-1,KGZDEW-T06,174321KYSB20160011,and XDPB06)
文摘Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide （GO） and completely reduced GO （rGO） membranes suffer florn low water permeance because of the lack of pristine graphitic sp2 domains and very small interlayer spacing, respectively. In this work, we studied the influence of reduction degree on the structure and separation pertornrance of rGO membranes, tt was found that weak reduction retains the good dispersion and hydrophilicity of GO nanosheets. More importantly, it increases the number of pristine graphitic sp2 domains in rGO nanosheets while keeping the large interlayer spacing of the GO membranes in most regions at the same time. The resultant mernbranes show a high water permeance of 56.3 L m^-2 h^ -1 bar^ -1, which is about 4 times and over 10^4 times larger tban those of the GO and completely reduced rGO membranes, respectively, and high rejection over 95700 for various dyes. Furthermore, they show better structure stability and more superior separation perfor- mance than GO membranes in acid and alkali environments.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Nos. 51422206 and 51372159）, 1000 Talents Plan for Young Researchers, ＂Shuangchuang＂ Program of Jiangsu Province, a Project Supported by Jiangsu Science and Technology Committee for Distinguished Young Scholars （No. BK20140009）, the National Basic Research Program of China （973 Program） （No. 2015CB358600） and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD）. We also acknowledge Jiangsu Nata Opto- electronic Materials Co. Ltd. for providing high purity TDMAT precursor for deposition of TiO2 thin films.
文摘Photoelectrodes with a specific structure and composition have been proposed for improving the efficiency of solar water splitting. Here, a novel multijunction structure was fabricated, with Si nanowires as cores, ZnIn2S4 nanosheets as branches, and TiO2 films as sandwiched layers. This junction exhibited a superior photoelectrochemical performance with a maximum photoconversion efficiency of 0.51%, which is 795 and 64 times higher than that of a bare Si wafer and nanowires, respectively. The large enhancement was attributed to the effective electron-hole separation and fast excited carrier transport within the multijunctions resulting from their favorable energy band alignments with water redox potentials, and to the enlarged contact area for facilitating the electron transfer at the multijunction/electrolyte interface.
文摘An inkjet-printed graphene film is of great importance for next-generation flexible, low cost and high performance electronic devices. However, due to the limitation of the inkjet printing process, the electrical conductivity of inkjet-printed graphene films is limited to N10 S＇cm-1, and achieving a high conductivity of the printed graphene films remains a big challenge. Here, we develop a ＂weak oxidation- vigorous exfoliation＂ strategy to tailor graphene oxide （GO） for meeting all the requirements of highly conductive inkjet-printed graphene films, including a more intact carbon plane and suitable size. The -conjugated structure of the resulting graphene has been restored to a high degree, and its printed films show an ultrahigh conductivity of -420 S-cm-I, which is tens of times higher than previously reported results, suggesting that, aside from developing a highly efficient reduction method, tuning the GO structure could be an alternative way to produce high quality graphene sheets. Using inkjet-printed graphene patterns as source/drain/gate electrodes, and semiconducting single-walled carbon nanotubes （SWCNTs） as channels, we fabricated an all-carbon field effect transistor which shows excellent performance （an on/off ratio of -104 and a mobility of -8 cm2＂V-l＇s-1） compared to previously reported CNT-based transistors, promising the use of nanocarbon materials, graphene and SWCNTs in printed electronics, especially where high performance and flexibility are needed.
