目的:观察中药外洗联合西药治疗霉菌性阴道炎的临床疗效。方法:选择郑州市金水区总医院妇产科收治的霉菌性阴道炎60例,按1∶1的比例随机分为两组。对照组给予酮康唑胶囊,1次2粒,1 d 1次,与饭同服;制霉菌素阴道栓,置入阴道后穹窿处,1次1...目的:观察中药外洗联合西药治疗霉菌性阴道炎的临床疗效。方法:选择郑州市金水区总医院妇产科收治的霉菌性阴道炎60例,按1∶1的比例随机分为两组。对照组给予酮康唑胶囊,1次2粒,1 d 1次,与饭同服;制霉菌素阴道栓,置入阴道后穹窿处,1次1粒,1 d 1次。治疗组在对照组治疗基础上给予自拟中药外洗方(苦参、黄柏、生百部、蛇床子、地肤子、土茯苓、花椒、蒲公英、大青叶、白鲜皮、赤芍、薄荷、生艾叶),每次30 min,1 d 1次,熏洗。两组均连续治疗10 d后判定疗效。结果:治疗组痊愈18例,有效10例,无效2例,有效率为93.33%(28/30);对照组痊愈10例,有效13例,无效7例,有效率为76.67%(23/30)。两组对比,差异有统计学意义(P<0.05)。在症状改善时间、不良反应、复发率方面对比,治疗组治疗后优于对照组(P<0.05)。结论:中药外洗联合西药治疗霉菌性阴道炎疗效确切。展开更多
A novel post-treatment method is reported for improving the field emission characteristics of screen-printed carbon nanotubes/nanofibers (CNTs/CNFs) cathodes. After the treatment at the temperature of 500℃ in H2 an...A novel post-treatment method is reported for improving the field emission characteristics of screen-printed carbon nanotubes/nanofibers (CNTs/CNFs) cathodes. After the treatment at the temperature of 500℃ in H2 and O2H2 gas for 20 minutes,the CNTs/CNFs cathodes exhibit much better field emission properties than those untreated. The emission current increases from 0.02 mA/cm^2 to 0.5 mA/cm^2 at 3.9 V/μm with a decrease in the turn-on field from 2.4 V to 1.8 V ,and the emission site density is increased by almost four orders in magnitude. The enhanced field emission of treated CNTs/CNFs cathodes is attributed to the appearance of a large number of exposed CNTs/CNFs caused by heat treatment. This surface morphology is very favorable for the electron field emission.展开更多
Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenge...Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenges that hinder the practical application of many important energy‐related electrocatalytic reactions.Compared with conventional wet‐chemical,solid‐state and vapor deposition synthesis,electrochemical synthesis is a simple,fast,cost‐effective and precisely controllable method for the preparation of highly efficient catalytic materials.In this review,we summarize recent progress in the electrochemical synthesis of catalytic materials such as single atoms,spherical and shaped nanoparticles,nanosheets,nanowires,core‐shell nanostructures,layered nanomaterials,dendritic nanostructures,hierarchically porous nanostructures as well as composite nanostructures.Fundamental aspects of electrochemical synthesis and several main electrochemical synthesis methods are discussed.Structure‐performance correlations between electrochemically synthesized catalysts and their unique electrocatalytic properties are exemplified using selected examples.We offer the reader with a basic guide to the synthesis of highly efficient catalysts using electrochemical methods,and we propose some research challenges and future opportunities in this field.展开更多
In this paper,nanosecond pulsed laser is introduced to selectively ablate away indium tin oxide film and metal film without destroying the underlying layers for fabricating organic light-emitting diodes.By varying den...In this paper,nanosecond pulsed laser is introduced to selectively ablate away indium tin oxide film and metal film without destroying the underlying layers for fabricating organic light-emitting diodes.By varying density of energy,pulse number and width of the laser,the influence on morphology of the laser trenches of indium tin oxide and metal films are investigated.It is presented that uniform ablation trench can be obtained with 16 laser pulses at 0.15 J/cm^2 for aluminum film and 10 laser pulses at 0.65 J/cm^2 for indium tin oxide film.It is found that the characteristics of the organic light-emitting diodes prepared with laser ablation are almost the same as those of that prepared with conventional patterning method.展开更多
An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the s...An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.展开更多
This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate-(as SiO2) were-studi...This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate-(as SiO2) were-studied in dual solution with arsenate. Moreover, the combined effect of ions and other water characteristics were examined with a natural groundwater sample which was spiked with a certain amount of arsenate. Arsenate batch adsorption experiments were carried out with two different kinds of maghemite-a commercially, available one and a homemade one using the sol-gel orocess. Sulohate (≤250 mg.L-1) and nitrate (≤ 12 mg.L-1) had a neglivible effect onthe arsenate (0.5 mg.L-1) adsorption at pH 3. However, both phosphate (42.9 mg·L-1) and silicate (450 mg.L-j) had an adverse impact on arsenate (43 mg.L-1) adsorption at pH 7. Phosphate (41.5 mg.L-1) showed minimal competition with arsenate (0.5 mg.L-1), while silicate (410 mg.L-1) inhibition was insignificant for all studied As(V) concentrations at p.H 3. The removal of arsenate from the groundwater sample was as efficient as from labo-ratory water tor 0.3 mgL -1 AS(V) botll at pH3 and pH7.展开更多
In this study, MWNT and alumina nanopowder were used as a ruthenium catalyst support for the conversion of carbon monoxide to methane. Metal foam structures were employed to support such catalytic systems, offering in...In this study, MWNT and alumina nanopowder were used as a ruthenium catalyst support for the conversion of carbon monoxide to methane. Metal foam structures were employed to support such catalytic systems, offering interesting possibilities for commercial applications due to low-pressure drop; excellent flow characteristic and heat transfer properties. Prior to the ruthenium impregnation, the MWNT surface was initially modified by means of metal cation activation and surface adsorption of anionic surfactant. The decoration processes using both surface modifications promoted the deposition of ruthenium with a mean 2 nm diameter. The use of nickel as a nucleating center enhanced the Ru nanoparticle density on the CNT surface compared to the Ru/CNT catalyst prepared by excess solution impregnation. As a reducing agent, ethylene glycol completely converted Ru2+ to Ru0as confirmed by an EDS/TEM analysis. Among the prepared catalysts, Ru/AI203-CNTs prepared by Ni2+ activation showed the best performance for the hydrogenation reaction. This is interpreted in terms of the higher ruthenium nanoparticle exposure on the nanostructured catalyst, as a result of the better MWNT dispersion in the MWNT/Al2O3 mixture.展开更多
Double-walled carbon nanotubes (DWCNTs) with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and mo...Double-walled carbon nanotubes (DWCNTs) with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and more than half of the DWCNTs have inner diameters in the range 0.6-1.0 nm. Field electron emission from a DWCNT cathode to an anode has been measured, and the emission current density of DWCNTs reached 1 A/cm2 at an applied field of about 4.3 V/~tm. After high-temperature treatment of DWCNTs, long linear carbon chains (C-chains) can be grown inside the ultra-thin DWCNTs to form a novel C-chain@DWCNT nanostructure, showing that these ultra-thin DWCNTs are an appropriate nanocontainer for preparing truly one-dimensional nanostructures with one-atom-diameter.展开更多
Metallic silver (Ag) and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver's efficacy to fight broad spectrum bacterial infections is further i...Metallic silver (Ag) and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver's efficacy to fight broad spectrum bacterial infections is further improved in the form of Ag nanoparticles (NPs). Recent studies have ascribed the broad spectrum antimicrobial properties of Ag NPs to dissociation of Ag* ions from the NPs, which may not be entirely applicable when the size of Ag NPs decreases to the sub-2 nm range [denoted Ag nanoclusters (NCs)]. In this paper we report that ultrasmall glutathione (GSH)-protected Ag^+-rich NCs (Ag^+-R NCs for short, with a predominance of Ag+ species in the NCs) have much higher antimicrobial activities towards both gram-negative and gram-positive bacteria than the reference NC, GSH-Ag^+-R NCs. They have the same size and surface ligand, but with different oxidation states of the core silver. This interesting finding suggests that the undissociated Ag^+-R NCs armed with abundant Ag^+ ions on the surface are highly active in bacterial killing, which was not observed in the system of their larger counterpart, Ag NPs.展开更多
Novel dual-responsive superhydrophobic hybrid materials, ZnO/SAMs (self-assembled monolayers) of ionic liquids (ILs) with different counter-anions (I^-, BF4^-, PF6^- and Tf2N^-), were synthesized and characteriz...Novel dual-responsive superhydrophobic hybrid materials, ZnO/SAMs (self-assembled monolayers) of ionic liquids (ILs) with different counter-anions (I^-, BF4^-, PF6^- and Tf2N^-), were synthesized and characterized. ZnO nanoparticles were first deposited on glass surfaces to produce roughness. Next, SAMs of fluorinated-alkyl-3-(3-triethoxysilylpropyl)-4,5-dihydro-imidazoliumiodide (abb. [C8Ftespim]I) were grafted onto these surfaces via -Si-O- covalent bonds using self-assembly technique. The I- ion could be subsequently exchanged with BF4, PF6-or Tf2N- through a simple aqueous anion-exchange reaction. The ZnO/ILs hybrid layers were characterized by atomic-force microscopy (AFM), scanning-electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Their wettability was estimated through the measurements of static and dynamic contact angles (CAs). Compared to corresponding films of ZnO/[CsFtespim]I with CAs 140.7° ±2.0°, films of ZnO/[CsFtespim]PF6 and ZnO/[CsFtespim]Tf2N showed CAs with 154.0° ± 2.0° and 152.0° ± 2.0°, respectively that remained for a long time. This result suggests that anion-exchange can afford superhydrophobic materials. In addition, the wettability of ZnO/[CsFtespim]X hybrid layers can be reversibly switched by altering ultraviolet (UV) irradiation and dark storage, which shows a photo-induced reversible switch of wettability. The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability.展开更多
Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube (CNT) cold cathode reaches 207.0 mA cm-2 at an electric ...Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube (CNT) cold cathode reaches 207.0 mA cm-2 at an electric field of 4.5 Vμm-1 under continuous driving mode, and high peak current emission of 315.8 mA corresponding to 4.5 A cm 2 at the electric field of 10.3 V μm-1 under pulsed driving mode. The emission patterns of the cold cathodes are of excellent uniformity that was revealed by vivid luminescent patterns of phosphor coated transparent indium tin oxide (ITO) an- ode. The cold cathodes also exhibit highly stable emission under continuous and pulsed driving modes. The high adhe- sion of CNTs to molybdenum substrates results in robust cold cathodes and is responsible for the high field emission performance. This robust CNT emitter could meet the operating requirements of continuous and pulsed electron sources, and it provides promising applications in various vacuum- micro/nanoelectronic devices.展开更多
Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur (Li-S) batteries. Herein, porous bamboo bi...Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur (Li-S) batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur (BC-S) nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency (995%). This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.展开更多
In this report we explore the structural and optical properties of GaAs/A1GaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-tempe...In this report we explore the structural and optical properties of GaAs/A1GaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-temperature cathodo- luminescence (CL) in a scanning electron microscope (SEM). We perform a systematic investigation of how the nanowire growth-temperature affects the total photon emission, and variations in the emission energy and intensity along the length of the nanowires. The morphology and crystal structures of the nanowires were investigated using SEM and transmission electron microscopy (TEM). In order to correlate specific photon emission characteristics with variations in the nanowire crystal structure directly, TEM and spatially resolved CL measurements were performed on the same individual nanowires. We found that the main emission energy was located at around 1.48 eV, and that the emission intensity was greatly enhanced when increasing the GaAs nanowire core growth temperature. The data strongly suggests that this emission energy is related to rotational twins in the GaAs nanowire core. Our measurements also show that radial overgrowth by GaAs on the GaAs nanowire core can have a deteriorating effect on the optical quality of the nanowires. Finally, we conclude that an in situ pre-growth annealing step at a sufficiently high temperature significantly improves the optical quality of the nanowires.展开更多
We investigated the cathode luminescence characteristics of CsI(Na)and CsI(Tl)crystals by the spectrum and structure properties at room temperature.We fabricated three different sizes of CsI(Na)and CsI(Tl)crystals and...We investigated the cathode luminescence characteristics of CsI(Na)and CsI(Tl)crystals by the spectrum and structure properties at room temperature.We fabricated three different sizes of CsI(Na)and CsI(Tl)crystals and measured their luminescence spectra under cathode rays.We found that CsI(Na)cathode luminescence peaks appear at 420 and 305 nm,and CsI(Tl)cathode luminescence peaks are 540 and 410 nm,the grain size affects CsI(Na)luminescence significantly,and the Na-related420 nm luminescence intensified relatively when the average grain size reaches^20μm,which becomes weak when the grain size is down to nano-scale.But the cathode luminescence spectra of CsI(Tl)crystals with different size have no obvious changes.Our explanations for these phenomena are that the different impurities in the same host material CsI lead to different luminescence mechanisms.These cathode luminescence characteristics indicate the suitability of CsI(Na)and CsI(Tl)crystals to match photomultiplier tube for large area crystal detector development.展开更多
Novel and highly durable air cathode electrocatalyst with three dimensional (3D)-clam-shaped structure, MnO2 nanotubes-supported Fe2O3 (Fe2O3/MnO2) composited by carbon nanotubes (CNTs) ((Fe2O3/ MnO2)3/4-(C...Novel and highly durable air cathode electrocatalyst with three dimensional (3D)-clam-shaped structure, MnO2 nanotubes-supported Fe2O3 (Fe2O3/MnO2) composited by carbon nanotubes (CNTs) ((Fe2O3/ MnO2)3/4-(CNTs)1/4) is synthesized using a facile hydrothermal process and a following direct heat- treatment in the air. The morphology and composition of this catalyst are analyzed using scanning elec- tronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The morphology characteristics reveal that flower-like Fe2O3 parti- cles are highly dispersed on both MnO2 nanotubes and CNT surfaces, coupling all three components firmly. Electrochemical measurements indicate that the synergy of catalyst exhibit superior bi- functional catalytic activity for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as well as stability than Pt/C and lrO2 catalysts. Using these catalysts for air-cathodes, both primary and rechargeable zinc-air batteries (ZABs) are assembled for performance validation. In a primary ZAB, this 3D-clamed catalyst shows a decent open circuit voltage (OCV, -1.48 V) and a high discharge peak power density (349 mW cm 2), corresponding to a coulomhic efficiency of 92%. In a rechargeahle ZABs with this bifunctional catalyst, high OCV (〉1.3 V) and small charge-discharge voltage gap (〈1.1 V) are achieved along with high specific capacity (780 mAh g 1 at 30 mA cm-2) and robust cycle-life (1,390 cycles at cycle profile of 20 mA/10 min).展开更多
The xonotlite fibers were synthesized via the hydrothermal synthesis method with CaO and SiO_2 as the raw materials and the molar ratio of Si/Ca of 1.0. Effect of anions from various calcium sources on the microstruct...The xonotlite fibers were synthesized via the hydrothermal synthesis method with CaO and SiO_2 as the raw materials and the molar ratio of Si/Ca of 1.0. Effect of anions from various calcium sources on the microstructure of the xonotlite fibers is studied in this paper. These obtained products were characterized by X-ray diffraction(XRD), transmission electron microscope(TEM) and scanning electron microscope(SEM) techniques to investigate their crystalline phase, crystal structure and morphology. The results indicate that anion from various calcium sources has little influence on the crystalline phases of xonotlite fibers but poses a great impact on their morphologies. Xonotlite fibers with single crystal characteristics and large aspect ratio of 50—100 were successfully fabricated from CaCl_2 as calcium material at 225 °C for 15 h. The existence of Cl-anion in the CaO-SiO_2-H_2O system significantly contributes to the formation of xonotlite crystal.展开更多
Laser was coupled into an optical fiber,on which covered a layer of well-aligned carbon nanotubes(CNTs)serving as cathode,to tune the field emission of the cathode.CNT arrays as field emission cathode were synthesized...Laser was coupled into an optical fiber,on which covered a layer of well-aligned carbon nanotubes(CNTs)serving as cathode,to tune the field emission of the cathode.CNT arrays as field emission cathode were synthesized by chemical vapor deposition(CVD)on a naked fiber core.When the laser was coupled into the fiber,the turn-on voltage(Vto at a current density of 1 mA cm?2)decreased from 1.0 to 0.9 kV and the emission current density increased from 0.83 mA cm?2(at a 1 kV bias voltage)to3.04 mA cm?2 on 40μm diameter fiber.A photon absorption mechanism is attributed to the field emission improvement.The estimated effective work function of CNT arrays on the optical fiber decrease from 4.89 to 4.29 eV.The results show the possibility of constructing a waveguide type laser modulated field emission cathode.展开更多
Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the met...Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the metal surface.CNTs were embedded into the Sn matrix,which acted as stable field emitters. The J-E curves show excellent field emission properties,such as low turn-on field of 2.8 V/μm,high emission current density and good current stability.展开更多
The TiN, TiA1N and TiA1SiN coatings were deposited on H13 hot-worked mold steel by cathodic arc ion plating (CAIP). The morphologies, phase compositions, and nanoindcntation parameters, such as creep hardness, elast...The TiN, TiA1N and TiA1SiN coatings were deposited on H13 hot-worked mold steel by cathodic arc ion plating (CAIP). The morphologies, phase compositions, and nanoindcntation parameters, such as creep hardness, elastic modulus and plastic de- formation energy of the coatings were analyzed with field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and nanoindentation testing, respectively, and the test results were compared with equation describing the indentation model. The results show that the TiN, TiA1N and TiAISiN coating surfaces were dense and composed of TiN, TiN + TiA1N, TiN + Si3N4 + TiAIN phases, respectively. There was no spalling or cracking on the indentation surface. The creep hardness of the TiN, TiA1N and TiAISiN coatings was 7.33, 13.5, and 15.2 GPa, respectively; the corresponding hardness measured by nanoindentation was 7.09, 15.6, and 21.7 GPa, respectively; and the corresponding elastic modulus was 201.93, 172.79, and 162.77 GPa, respectively. The contact depth and elastic modulus calculated by the indentation model were close to those of the test results, but the remaining indentation parameters showed discrepancies. The sequence of plastic deformation energy was TiN 〉 TiA1N〉TiAISiN.展开更多
文摘目的:观察中药外洗联合西药治疗霉菌性阴道炎的临床疗效。方法:选择郑州市金水区总医院妇产科收治的霉菌性阴道炎60例,按1∶1的比例随机分为两组。对照组给予酮康唑胶囊,1次2粒,1 d 1次,与饭同服;制霉菌素阴道栓,置入阴道后穹窿处,1次1粒,1 d 1次。治疗组在对照组治疗基础上给予自拟中药外洗方(苦参、黄柏、生百部、蛇床子、地肤子、土茯苓、花椒、蒲公英、大青叶、白鲜皮、赤芍、薄荷、生艾叶),每次30 min,1 d 1次,熏洗。两组均连续治疗10 d后判定疗效。结果:治疗组痊愈18例,有效10例,无效2例,有效率为93.33%(28/30);对照组痊愈10例,有效13例,无效7例,有效率为76.67%(23/30)。两组对比,差异有统计学意义(P<0.05)。在症状改善时间、不良反应、复发率方面对比,治疗组治疗后优于对照组(P<0.05)。结论:中药外洗联合西药治疗霉菌性阴道炎疗效确切。
文摘A novel post-treatment method is reported for improving the field emission characteristics of screen-printed carbon nanotubes/nanofibers (CNTs/CNFs) cathodes. After the treatment at the temperature of 500℃ in H2 and O2H2 gas for 20 minutes,the CNTs/CNFs cathodes exhibit much better field emission properties than those untreated. The emission current increases from 0.02 mA/cm^2 to 0.5 mA/cm^2 at 3.9 V/μm with a decrease in the turn-on field from 2.4 V to 1.8 V ,and the emission site density is increased by almost four orders in magnitude. The enhanced field emission of treated CNTs/CNFs cathodes is attributed to the appearance of a large number of exposed CNTs/CNFs caused by heat treatment. This surface morphology is very favorable for the electron field emission.
文摘Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenges that hinder the practical application of many important energy‐related electrocatalytic reactions.Compared with conventional wet‐chemical,solid‐state and vapor deposition synthesis,electrochemical synthesis is a simple,fast,cost‐effective and precisely controllable method for the preparation of highly efficient catalytic materials.In this review,we summarize recent progress in the electrochemical synthesis of catalytic materials such as single atoms,spherical and shaped nanoparticles,nanosheets,nanowires,core‐shell nanostructures,layered nanomaterials,dendritic nanostructures,hierarchically porous nanostructures as well as composite nanostructures.Fundamental aspects of electrochemical synthesis and several main electrochemical synthesis methods are discussed.Structure‐performance correlations between electrochemically synthesized catalysts and their unique electrocatalytic properties are exemplified using selected examples.We offer the reader with a basic guide to the synthesis of highly efficient catalysts using electrochemical methods,and we propose some research challenges and future opportunities in this field.
文摘In this paper,nanosecond pulsed laser is introduced to selectively ablate away indium tin oxide film and metal film without destroying the underlying layers for fabricating organic light-emitting diodes.By varying density of energy,pulse number and width of the laser,the influence on morphology of the laser trenches of indium tin oxide and metal films are investigated.It is presented that uniform ablation trench can be obtained with 16 laser pulses at 0.15 J/cm^2 for aluminum film and 10 laser pulses at 0.65 J/cm^2 for indium tin oxide film.It is found that the characteristics of the organic light-emitting diodes prepared with laser ablation are almost the same as those of that prepared with conventional patterning method.
基金supported by the National Natural Science Foundation of China (11405144)the Fundamental Research Funds for the Central Universities (20720180081)~~
文摘An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.
文摘This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate-(as SiO2) were-studied in dual solution with arsenate. Moreover, the combined effect of ions and other water characteristics were examined with a natural groundwater sample which was spiked with a certain amount of arsenate. Arsenate batch adsorption experiments were carried out with two different kinds of maghemite-a commercially, available one and a homemade one using the sol-gel orocess. Sulohate (≤250 mg.L-1) and nitrate (≤ 12 mg.L-1) had a neglivible effect onthe arsenate (0.5 mg.L-1) adsorption at pH 3. However, both phosphate (42.9 mg·L-1) and silicate (450 mg.L-j) had an adverse impact on arsenate (43 mg.L-1) adsorption at pH 7. Phosphate (41.5 mg.L-1) showed minimal competition with arsenate (0.5 mg.L-1), while silicate (410 mg.L-1) inhibition was insignificant for all studied As(V) concentrations at p.H 3. The removal of arsenate from the groundwater sample was as efficient as from labo-ratory water tor 0.3 mgL -1 AS(V) botll at pH3 and pH7.
文摘In this study, MWNT and alumina nanopowder were used as a ruthenium catalyst support for the conversion of carbon monoxide to methane. Metal foam structures were employed to support such catalytic systems, offering interesting possibilities for commercial applications due to low-pressure drop; excellent flow characteristic and heat transfer properties. Prior to the ruthenium impregnation, the MWNT surface was initially modified by means of metal cation activation and surface adsorption of anionic surfactant. The decoration processes using both surface modifications promoted the deposition of ruthenium with a mean 2 nm diameter. The use of nickel as a nucleating center enhanced the Ru nanoparticle density on the CNT surface compared to the Ru/CNT catalyst prepared by excess solution impregnation. As a reducing agent, ethylene glycol completely converted Ru2+ to Ru0as confirmed by an EDS/TEM analysis. Among the prepared catalysts, Ru/AI203-CNTs prepared by Ni2+ activation showed the best performance for the hydrogenation reaction. This is interpreted in terms of the higher ruthenium nanoparticle exposure on the nanostructured catalyst, as a result of the better MWNT dispersion in the MWNT/Al2O3 mixture.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 10974131), the Nanotechnology Program of Shanghai Science and Technology Committee (No. 0952nm07100), the Scienceand Technology Innovation Fund of the Shanghai Education Committee (No. 09ZZ85) and Shanghai Pujiang Talent Plan (No. 08PJ1405100). We thank Professor Shoushan Fan of Tsinghua-Foxconn Nanotechnology Research Center for the HRTEM measurements, and Professor Pingheng Tan of the Institute of Semiconductors for some of the Raman measurements.
文摘Double-walled carbon nanotubes (DWCNTs) with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and more than half of the DWCNTs have inner diameters in the range 0.6-1.0 nm. Field electron emission from a DWCNT cathode to an anode has been measured, and the emission current density of DWCNTs reached 1 A/cm2 at an applied field of about 4.3 V/~tm. After high-temperature treatment of DWCNTs, long linear carbon chains (C-chains) can be grown inside the ultra-thin DWCNTs to form a novel C-chain@DWCNT nanostructure, showing that these ultra-thin DWCNTs are an appropriate nanocontainer for preparing truly one-dimensional nanostructures with one-atom-diameter.
文摘Metallic silver (Ag) and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver's efficacy to fight broad spectrum bacterial infections is further improved in the form of Ag nanoparticles (NPs). Recent studies have ascribed the broad spectrum antimicrobial properties of Ag NPs to dissociation of Ag* ions from the NPs, which may not be entirely applicable when the size of Ag NPs decreases to the sub-2 nm range [denoted Ag nanoclusters (NCs)]. In this paper we report that ultrasmall glutathione (GSH)-protected Ag^+-rich NCs (Ag^+-R NCs for short, with a predominance of Ag+ species in the NCs) have much higher antimicrobial activities towards both gram-negative and gram-positive bacteria than the reference NC, GSH-Ag^+-R NCs. They have the same size and surface ligand, but with different oxidation states of the core silver. This interesting finding suggests that the undissociated Ag^+-R NCs armed with abundant Ag^+ ions on the surface are highly active in bacterial killing, which was not observed in the system of their larger counterpart, Ag NPs.
基金financially supported by the National Natural Science Foundation of China(21033005,21273134)the National Basic Research Program of China(2009CB930103)+2 种基金the Natural Science Foundation of Shandong Province(Combination Research Projects,ZR2013EML003&ZR2013BL001)National Undergraduate Training Programs for Innovation and Entrepreneurship(201310448008)Research Projects of Solar Energy of Dezhou University(311416&SYJS-B13003)
文摘Novel dual-responsive superhydrophobic hybrid materials, ZnO/SAMs (self-assembled monolayers) of ionic liquids (ILs) with different counter-anions (I^-, BF4^-, PF6^- and Tf2N^-), were synthesized and characterized. ZnO nanoparticles were first deposited on glass surfaces to produce roughness. Next, SAMs of fluorinated-alkyl-3-(3-triethoxysilylpropyl)-4,5-dihydro-imidazoliumiodide (abb. [C8Ftespim]I) were grafted onto these surfaces via -Si-O- covalent bonds using self-assembly technique. The I- ion could be subsequently exchanged with BF4, PF6-or Tf2N- through a simple aqueous anion-exchange reaction. The ZnO/ILs hybrid layers were characterized by atomic-force microscopy (AFM), scanning-electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Their wettability was estimated through the measurements of static and dynamic contact angles (CAs). Compared to corresponding films of ZnO/[CsFtespim]I with CAs 140.7° ±2.0°, films of ZnO/[CsFtespim]PF6 and ZnO/[CsFtespim]Tf2N showed CAs with 154.0° ± 2.0° and 152.0° ± 2.0°, respectively that remained for a long time. This result suggests that anion-exchange can afford superhydrophobic materials. In addition, the wettability of ZnO/[CsFtespim]X hybrid layers can be reversibly switched by altering ultraviolet (UV) irradiation and dark storage, which shows a photo-induced reversible switch of wettability. The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability.
基金supported by the National Natural Science Foundation of China(51002161)One-Three-Five Strategic Planning of Chinese Academy of Sciences
文摘Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube (CNT) cold cathode reaches 207.0 mA cm-2 at an electric field of 4.5 Vμm-1 under continuous driving mode, and high peak current emission of 315.8 mA corresponding to 4.5 A cm 2 at the electric field of 10.3 V μm-1 under pulsed driving mode. The emission patterns of the cold cathodes are of excellent uniformity that was revealed by vivid luminescent patterns of phosphor coated transparent indium tin oxide (ITO) an- ode. The cold cathodes also exhibit highly stable emission under continuous and pulsed driving modes. The high adhe- sion of CNTs to molybdenum substrates results in robust cold cathodes and is responsible for the high field emission performance. This robust CNT emitter could meet the operating requirements of continuous and pulsed electron sources, and it provides promising applications in various vacuum- micro/nanoelectronic devices.
文摘Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur (Li-S) batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur (BC-S) nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency (995%). This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.
文摘In this report we explore the structural and optical properties of GaAs/A1GaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-temperature cathodo- luminescence (CL) in a scanning electron microscope (SEM). We perform a systematic investigation of how the nanowire growth-temperature affects the total photon emission, and variations in the emission energy and intensity along the length of the nanowires. The morphology and crystal structures of the nanowires were investigated using SEM and transmission electron microscopy (TEM). In order to correlate specific photon emission characteristics with variations in the nanowire crystal structure directly, TEM and spatially resolved CL measurements were performed on the same individual nanowires. We found that the main emission energy was located at around 1.48 eV, and that the emission intensity was greatly enhanced when increasing the GaAs nanowire core growth temperature. The data strongly suggests that this emission energy is related to rotational twins in the GaAs nanowire core. Our measurements also show that radial overgrowth by GaAs on the GaAs nanowire core can have a deteriorating effect on the optical quality of the nanowires. Finally, we conclude that an in situ pre-growth annealing step at a sufficiently high temperature significantly improves the optical quality of the nanowires.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.11QG14)
文摘We investigated the cathode luminescence characteristics of CsI(Na)and CsI(Tl)crystals by the spectrum and structure properties at room temperature.We fabricated three different sizes of CsI(Na)and CsI(Tl)crystals and measured their luminescence spectra under cathode rays.We found that CsI(Na)cathode luminescence peaks appear at 420 and 305 nm,and CsI(Tl)cathode luminescence peaks are 540 and 410 nm,the grain size affects CsI(Na)luminescence significantly,and the Na-related420 nm luminescence intensified relatively when the average grain size reaches^20μm,which becomes weak when the grain size is down to nano-scale.But the cathode luminescence spectra of CsI(Tl)crystals with different size have no obvious changes.Our explanations for these phenomena are that the different impurities in the same host material CsI lead to different luminescence mechanisms.These cathode luminescence characteristics indicate the suitability of CsI(Na)and CsI(Tl)crystals to match photomultiplier tube for large area crystal detector development.
基金supported by the National Natural Science Foundation of China(U1510120)Natural Science Foundation of Shanghai(14ZR1400700)+2 种基金the Project of Introducing Overseas Intelligence High Education of China(2017-2018)the Graduate Thesis Innovation Foundation of Donghua University(EG2017031,EG2016034)the College of Environmental Science and Engineering,State Environmental Protection Engineering Centre for Pollution Treatment and Control in Textile Industry,Donghua University
文摘Novel and highly durable air cathode electrocatalyst with three dimensional (3D)-clam-shaped structure, MnO2 nanotubes-supported Fe2O3 (Fe2O3/MnO2) composited by carbon nanotubes (CNTs) ((Fe2O3/ MnO2)3/4-(CNTs)1/4) is synthesized using a facile hydrothermal process and a following direct heat- treatment in the air. The morphology and composition of this catalyst are analyzed using scanning elec- tronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The morphology characteristics reveal that flower-like Fe2O3 parti- cles are highly dispersed on both MnO2 nanotubes and CNT surfaces, coupling all three components firmly. Electrochemical measurements indicate that the synergy of catalyst exhibit superior bi- functional catalytic activity for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as well as stability than Pt/C and lrO2 catalysts. Using these catalysts for air-cathodes, both primary and rechargeable zinc-air batteries (ZABs) are assembled for performance validation. In a primary ZAB, this 3D-clamed catalyst shows a decent open circuit voltage (OCV, -1.48 V) and a high discharge peak power density (349 mW cm 2), corresponding to a coulomhic efficiency of 92%. In a rechargeahle ZABs with this bifunctional catalyst, high OCV (〉1.3 V) and small charge-discharge voltage gap (〈1.1 V) are achieved along with high specific capacity (780 mAh g 1 at 30 mA cm-2) and robust cycle-life (1,390 cycles at cycle profile of 20 mA/10 min).
基金supported by the National Natural Science Foundation of China(No.21666007)the Science Technology Foundation of Guizhou Province(No.2014-2007)the Program for “Hundred” High-Level Talents in Guizhou Province(No.2016-5655)
文摘The xonotlite fibers were synthesized via the hydrothermal synthesis method with CaO and SiO_2 as the raw materials and the molar ratio of Si/Ca of 1.0. Effect of anions from various calcium sources on the microstructure of the xonotlite fibers is studied in this paper. These obtained products were characterized by X-ray diffraction(XRD), transmission electron microscope(TEM) and scanning electron microscope(SEM) techniques to investigate their crystalline phase, crystal structure and morphology. The results indicate that anion from various calcium sources has little influence on the crystalline phases of xonotlite fibers but poses a great impact on their morphologies. Xonotlite fibers with single crystal characteristics and large aspect ratio of 50—100 were successfully fabricated from CaCl_2 as calcium material at 225 °C for 15 h. The existence of Cl-anion in the CaO-SiO_2-H_2O system significantly contributes to the formation of xonotlite crystal.
基金supported by the National Natural Science Foundation of China(Grant Nos.91123018,61172041,61172040,50975226,and 60801022)the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2008AA03A314)the Fundamental Research Funds for the Central Universities
文摘Laser was coupled into an optical fiber,on which covered a layer of well-aligned carbon nanotubes(CNTs)serving as cathode,to tune the field emission of the cathode.CNT arrays as field emission cathode were synthesized by chemical vapor deposition(CVD)on a naked fiber core.When the laser was coupled into the fiber,the turn-on voltage(Vto at a current density of 1 mA cm?2)decreased from 1.0 to 0.9 kV and the emission current density increased from 0.83 mA cm?2(at a 1 kV bias voltage)to3.04 mA cm?2 on 40μm diameter fiber.A photon absorption mechanism is attributed to the field emission improvement.The estimated effective work function of CNT arrays on the optical fiber decrease from 4.89 to 4.29 eV.The results show the possibility of constructing a waveguide type laser modulated field emission cathode.
基金the National Natural Science Foundation of China(No.50730008)the National Basic Research Program(973)of China(No.2006CB300406)
文摘Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the metal surface.CNTs were embedded into the Sn matrix,which acted as stable field emitters. The J-E curves show excellent field emission properties,such as low turn-on field of 2.8 V/μm,high emission current density and good current stability.
基金supported by the Jiangsu Province Science and Technology Support Program(Industry)(Grant No.BE2014818)
文摘The TiN, TiA1N and TiA1SiN coatings were deposited on H13 hot-worked mold steel by cathodic arc ion plating (CAIP). The morphologies, phase compositions, and nanoindcntation parameters, such as creep hardness, elastic modulus and plastic de- formation energy of the coatings were analyzed with field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and nanoindentation testing, respectively, and the test results were compared with equation describing the indentation model. The results show that the TiN, TiA1N and TiAISiN coating surfaces were dense and composed of TiN, TiN + TiA1N, TiN + Si3N4 + TiAIN phases, respectively. There was no spalling or cracking on the indentation surface. The creep hardness of the TiN, TiA1N and TiAISiN coatings was 7.33, 13.5, and 15.2 GPa, respectively; the corresponding hardness measured by nanoindentation was 7.09, 15.6, and 21.7 GPa, respectively; and the corresponding elastic modulus was 201.93, 172.79, and 162.77 GPa, respectively. The contact depth and elastic modulus calculated by the indentation model were close to those of the test results, but the remaining indentation parameters showed discrepancies. The sequence of plastic deformation energy was TiN 〉 TiA1N〉TiAISiN.