This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(...This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.展开更多
SnO2 nanoparticles with the average particle size of 5-30 nm were synthesized using SnCl4·5H2O as the precursor and NH3·H2O as the mineralizing agent by hydrothermal method.In the case of 1 kg/batch producti...SnO2 nanoparticles with the average particle size of 5-30 nm were synthesized using SnCl4·5H2O as the precursor and NH3·H2O as the mineralizing agent by hydrothermal method.In the case of 1 kg/batch production,the effects of synthesis conditions including solution concentration,reaction temperature,pressure,time and pH value on the grain size,particle morphology and crystal structure of SnO2 were systematically studied.The particles were characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）.The results show that,the particle size can be well controlled in the range of 5-30 nm by adjusting the processing parameters such as reaction temperature and time when the crystal structure and particle morphology remain unchanged.The previous reports,the unusual dependences of the grain size of SnO2 on reaction temperature and time were found.The mechanism for such abnormal grain growth behavior was tentatively elucidated.展开更多
The semiconductor TiO_(2)is the most important photocatalyst for the degradation of pollutants.Anatase TiO_(2)has a large band gap of 3.2 eV that requires powerful UV light to initiate the photocatalytic reactions.Man...The semiconductor TiO_(2)is the most important photocatalyst for the degradation of pollutants.Anatase TiO_(2)has a large band gap of 3.2 eV that requires powerful UV light to initiate the photocatalytic reactions.Many modifịcation methods such as metal ion doping,composite semiconductors and metal layer modification have been used to extend the light absorption of the catalyst to the visible light region but have little effect[1~4].Surface sensitization with dyes[5]is not practical in application as most dyes self-degrade easily.Therefore,the preparation of TiO_(2)with good wavelength response in the visible light region and high photocatalytic activity for pollutant degradation using natural sunlight is an important goal in TiO_(2)photocatalysis.展开更多
Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the imp...Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.展开更多
LiCoPO4 micron-rods with an average diameter of about 500 nm and length of about 5 μm were synthesized by dispersant-aided hydrothermal method. Poly(n-vinylpyrrolidone) (PVP) was used as dispersant in the hydrotherma...LiCoPO4 micron-rods with an average diameter of about 500 nm and length of about 5 μm were synthesized by dispersant-aided hydrothermal method. Poly(n-vinylpyrrolidone) (PVP) was used as dispersant in the hydrothermal method. The starting solution and the concentration of dispersant have significant influences on the morphology of LiCoPO4,and the electrochemical performance is improved via controlling the particle size and morphology by the hydrothermal method. The cell using smaller particle LiCoPO4 as cat...展开更多
pH value is a key factor in the preparation of nano-sized TiO2 with hydrothermal method. Using Ti（SO4）2 as the titanium source, H2O2 as the complexing agent, NaOH and HCl as the pH value regulator, nano- sized TiO2 ...pH value is a key factor in the preparation of nano-sized TiO2 with hydrothermal method. Using Ti（SO4）2 as the titanium source, H2O2 as the complexing agent, NaOH and HCl as the pH value regulator, nano- sized TiO2 powder with various morphologies and sizes was synthesized. Changes in morphology, size and phase type with pH values of samples were characterized by X-ray diffraction （XRD） and transmission electron micro- scopy （TEM） measurements. Results show that under the present preparation conditions, TiO2 powder is an anatase phase with pH value less than 11, but is more likely to be a brookite phase with pH value more than 11. With the increase in pH value from 1 to 11 in hydrothermal envi- ronment, nano-sized anatase TiO2 gradually grows up in all directions. {001 }, { 101 } and { 100} groups of crystal plane are the exposed crystal planes of nano-sized anatase TiO2 for the （004）, （101） and （200） facets found in high-reso- lution TEM image. The photocatalytic performance of nano-sized TiO2 with different morphologies was com- pared by measuring their photocatalytic degradation rates for methylene blue under ultraviolet light. Results show that anatase TiO2 prepared under the alkalescenthydrothermal environment （pH = 9, 11） has a better pho- tocatalytic degrading performance. Different sizes and phases of nanoscaled TiO2 powders with different photo- catalytic performances can be prepared by the control of pH value of hydrothermal solutions.展开更多
Silicon is one of the most promising anode materials for lithium-ion batteries(LIBs), but it suffers from pulverization and hence poor cycling stability due to the large volume variation during lithiation/delithiation...Silicon is one of the most promising anode materials for lithium-ion batteries(LIBs), but it suffers from pulverization and hence poor cycling stability due to the large volume variation during lithiation/delithiation. The core-shell structure is considered as an effective strategy to solve the expansion problem of silicon-based anodes. In this paper, the double-shell structured Si@SnO_(2) @C nanocomposite with nano-silicon as the core and SnO_(2) , C as the shells is synthesized by a facile hydrothermal method.Structural characterization shows that Si@SnO_(2) @C nanocomposite is composed of crystalline Si, crystalline SnO_(2) and amorphous C, and the contents of them are 42.1wt%, 37.8 wt% and 20.1 wt%, respectively. Transmission electron microscope(TEM) observations confirm the double-shell structure of Si@SnO_(2) @C nanocomposite, and the thicknesses of the SnO_(2) and C layers are 20 and 7 nm. The Si@SnO_(2) @C electrode exhibits a high initial discharge capacity of 2777 mAh·g^(-1)at 100 mA·g^(-1)and an excellent rate capability of 340 mAh·g^(-1)at 1500 mA·g^(-1). The outstanding capacity retention is 50.2% after 300 cycles over a potential of 0.01 to 2.00 V(vs. Li/Li+) at 500 mA·g^(-1). The resistance of solid electrolyte interphase(SEI) film(Rf) and charge transfer resistance(Rct) of Si@SnO_(2) @C are 7.68and 0.82 Ω, which are relatively smaller than those of Si@C(21.64 and 2.62 Ω). It is obviously seen that the SnO_(2) shell can reduce the charge transfer resistance, leading to high ion and electron transport efficiency in the Si@SnO_(2) @C electrode. The incorporation of SnO_(2) shell is attributed to the enhanced rate capability and cycling performance of Si@SnO_(2) @C nanocomposite.展开更多
The europium ions doped MMoO4 （M=Sr, Ba） nanophosphors were successfully synthesized via a facile hydrothermal method using isopropanol. The relationship between phosphor crystalline phase, morphology, photohtminesc...The europium ions doped MMoO4 （M=Sr, Ba） nanophosphors were successfully synthesized via a facile hydrothermal method using isopropanol. The relationship between phosphor crystalline phase, morphology, photohtminescent properties and hexadecyl trimethyl ammonium bromide （CTAB） concentration, pH value in precursor solution was investigated. The results indi- cated that the morphology and photoluminescent properties were strongly influenced by CTAB concentration and pH value in precursor solution. In SrMoO4：Eu3＋ hosts, the phosphor surface tended to become smoother as the concentration of CTAB was increased; while particles tended to agglomerate as increasing pH value. The relative intensity ratio of charge transfer band to Eu3＋ characteristic emission peaks of MMoO4：Eu3＋ （M=Sr, Ba） was changed as CTAB concentration and pH value changed. The emission spectra of MMoO4：Eu3＋ （M=Sr, Ba） could be adjusted by CTAB concentration and pH value due to their impacts on the structure. It was im- portant that the different morphologies and photoluminescent properties of MMoO4：Eu3＋ （M=Sr, Ba） could be obtained by the facile hydrothermal method and modulated by changing CTAB concentration and pH value.展开更多
NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, trans...NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, UV–visible（UV–vis） diffuse reflectance spectroscopy, and photoluminescence（PL） spectroscopy. The XRD patterns of the H-and S-samples showed peaks indexed to the pure phase of perovskite NaTaOand minor peaks assignable to TaNat various synthesis temperatures. Substitution of oxygen by nitrogen ions causes the light absorption of the H-and S-NaTaONsamples to be extended to the 600–650 nm region, thus making the samples visible-light active. The NaTaONsamples exhibited photocatalytic activity for Hand Oevolution from aqueous methanol and silver nitrate solutions under visible-light irradiation. The UV–vis and PL spectra of the Hand S-catalysts revealed the presence of cationic vacancies and reduced metallic species, which acted as recombination centers. These results demonstrated that the preparation method plays a critical role in the formation of defect states, thereby governing the photocatalytic activity of the NaTaONcatalysts.展开更多
In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission...In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）. scanning electron microscope（SEM） and Brunauer-Emmett-Teller（BET）.The prepared TiO_2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested.Results show the prepared TiO_2 nanotube gas sensors responses to ethanol under dry condition at 450℃.This could be attributed to the fact that it had high porous morphology and a higher pore volume,which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover,the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H_2,CO,acetone.展开更多
Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical S...Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.展开更多
Pure ZnS and Ni^2+-doped ZnS nanorods (Zn1-xNixS, x=0, 0.01, 0.03, 0.05 and 0.07, mole fraction,%) were synthesized by hydrothermal method. The effects of Ni2+ doping on the phase-structure, morphology, elemental comp...Pure ZnS and Ni^2+-doped ZnS nanorods (Zn1-xNixS, x=0, 0.01, 0.03, 0.05 and 0.07, mole fraction,%) were synthesized by hydrothermal method. The effects of Ni2+ doping on the phase-structure, morphology, elemental composition and optical properties of the samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (EDS) and ultraviolet–visible spectroscopy (UV-Vis), respectively. The photocatalytic activity of Zn1-xNixS nanorods was evaluated by the photodegradation of organic dyes Rhodamine B (RhB) in aqueous solution under UV light irradiation. The results show that all samples exhibit wurtzite structure with good crystallization. The morphologies are one-dimensional nanorods with good dispersion, and the distortion of the lattice constant occurs. The band gap of Zn1-xNixS samples is smaller than that of pure ZnS, thus red shift occurs. Ni^2+-doped ZnS nanocrystals can enhance photocatalytic activities for the photodegradation of RhB. Especially, Zn0.97Ni0.03S sample exhibits better photocatalytic performance and photocatalytic stability for the decomposition of RhB.展开更多
Hydro-sodalites are zeolitic materials with a wide variety of applications.Fly ash is an abundant industrial solid waste,rich in silicon and aluminum,from which hydro-sodalite can be synthesized.However,traditional hy...Hydro-sodalites are zeolitic materials with a wide variety of applications.Fly ash is an abundant industrial solid waste,rich in silicon and aluminum,from which hydro-sodalite can be synthesized.However,traditional hydrothermal synthesis methods are complex and cannot produce high-purity products.Therefore,there is a demand for processing routes to obtain high-purity hydro-sodalites.In the present study,high-purity hydro-sodalite(90.2 wt%)was prepared from fly ash by applying a hydrothermal method to a submolten salt system.Samples were characterized by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetry and differential thermal analysis(TG–DTA),and Fourier transform infrared spectroscopy(FTIR)to confirm and quantify conversion of the raw material into the product phase.Purity of the samples prepared with an H2O/Na OH mass ratio of 1.5 and an H2O/fly ash mass ratio of 10 was calculated and the conversion process of the product phase was studied.Crystallinity of the product was influenced more by the Na OH concentration,less by the H2O/fly ash mass ratio.The main reaction process of the system is that the Si O ions produced by dissolution of the vitreous body in the fly ash and Na+ions in the solution reacted on the destroyed mullite skeleton to produce hydro-sodalite.This processing route could help mitigate processing difficulties,while producing high-purity hydro-sodalite from fly ash.展开更多
High quality potassium hexatitanate whiskers were hydrothermally synthesized in one step under moderate temperature and pressure conditions. Effects of the titanium source and reaction conditions on the hydrothermal r...High quality potassium hexatitanate whiskers were hydrothermally synthesized in one step under moderate temperature and pressure conditions. Effects of the titanium source and reaction conditions on the hydrothermal reaction rate, product phase component, and morphology of whiskers were investigated. The results show that the reactivity of hydrated titania, anatase TiO2, and rutile TiO2 with KOH decreases in turn, and with hydrated titania as titanium source, it is difficult to obtain potassium hexatitanate whiskers with good morphology. In contrast, uniform potassium hexatitanate whiskers with a length of 10-20 μm and a diameter of 200-700 nm were obtained using anatase TiO2 as titanium source. The investigation demonstrates that the initial KOH concentration, annealing temperature and time, molar ratio of K2O/TiO2, etc. significantly affect the morphology of the as-synthesized whiskers. The optimized synthesis condition is as follows： anatase as a titanium source 10 wt.% KOH solution; annealing temperature and time of 300℃ and 5 h, respectively; K2O/TiO2 molar ratio of 5, etc. A rhombic potassium hexatitanate was prepared under the optimum condition and the whisker grew along the [110] direction. The reaction mechanism was discussed.展开更多
Lead zirconate titanium solid-solution (PZT) thin films with variousthickness are synthesized on titanium substrates by repeated hydrothermal treatments. Young modulus,electric-field-induced displacement and the densi...Lead zirconate titanium solid-solution (PZT) thin films with variousthickness are synthesized on titanium substrates by repeated hydrothermal treatments. Young modulus,electric-field-induced displacement and the density of the PZT film are measured respectively.Bimorph- type bending actuators are fabricated using these films. The model, which is used toanalyze the driving ability of bimorph-type bending actuators by hydrothermal method, is set up. Itcan be seen that the driving ability of bimorph-type bending actuators can be greatly improved byoptimizing the thickness of PZT thin film and substrate from the theoretical analysis results. Themeasured values are expected to agree with the theoretical values calculated by the above model.展开更多
The Ni(OH)2/SiO2 binary colloid was prepared using Ni(NO3)2.6H2O and (C2H5O)4SiO4 as starting materials and was used to form NiO/SiO2. composite powder by hydrothermal method and desiccant method in open air respectiv...The Ni(OH)2/SiO2 binary colloid was prepared using Ni(NO3)2.6H2O and (C2H5O)4SiO4 as starting materials and was used to form NiO/SiO2. composite powder by hydrothermal method and desiccant method in open air respectively. Multi-walled carbon nanotubes (MWCNTs) were synthesized respectively by chemical vapor deposition using the NiO/SiO2 catalyst prepared by different methods. The phase and morphology of the catalysts and the morphology, output yield and purity of MWCNTs were compared by XRD, TEM and SEM. The results show that the catalyst powder prepared by hydrothermal method, compared with that by desiccant method, is smaller, better dispersion and has stronger catalytic activity. Pure MWCNTs with smaller tube diameter and narrow range could be obtained at a high yield using that NiO/SiO2 powder prepared by hydrothermal method as catalyst.展开更多
Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray...Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray powder diffraction （XRD）,field emission scanning electron microscopy （FESEM） and energy dispersive spectroscopy （EDS）.The influence of hydrothermal temperature,precursor solution concentration on the crystal and morphology of products were further studied.The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure.The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles.Furthermore,the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.展开更多
Different morphologies of zinc oxide（ZnO）,including microrods,hexagonal pyramid-like rods and flower-like rod aggregates,had been synthesized,respectively,on glass substrates by controlling the reaction conditions（...Different morphologies of zinc oxide（ZnO）,including microrods,hexagonal pyramid-like rods and flower-like rod aggregates,had been synthesized,respectively,on glass substrates by controlling the reaction conditions（such as precursor concentration,reaction time and pH value） of hydrothermal method.The morphologies of the as-obtained ZnO were observed with scanning electron microscopy and transmission electron microscopy.Also,the crystalline natures of different ZnO crystals were analyzed with X-ray diffraction.The possible growth mechanism of ZnO crystals with different morphologies was discussed.展开更多
Micaceous iron oxide （MIO） with a hexagonal flaky shape was prepared by hydrothermal method. The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia...Micaceous iron oxide （MIO） with a hexagonal flaky shape was prepared by hydrothermal method. The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution. The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments. Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L, pH value of 8, n（Fe2＋）/n（Fe3＋） of 0.1, mass of seed crystal of 1 g, reaction temperature of 260 ℃ and reaction time of 30 min are applied. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and selected area electron diffractometry （SAEM） were adopted to characterize the hydrothermal products prepared under optimal conditions. The results indicate that highly crystallized α-Fe2O3 hexagonal flakes, about 1.0-1.5 μm in diameter and 0.1 μm in thickness, are prepared. Furthermore, the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints （ISO 10601--2007）.展开更多
ZnO film with claviform structure was synthesized on quartz substrates through a hydrothermal method at 90℃. The microstructure of the film is composed of clusters of submicrometer rods, which therefore endues the fi...ZnO film with claviform structure was synthesized on quartz substrates through a hydrothermal method at 90℃. The microstructure of the film is composed of clusters of submicrometer rods, which therefore endues the film with good superhydrophobicity. Meanwhile, the film with such tanglesome structure also shows highly crystalline quality testified by a strong ultra-violet （UV） emission and very low deep-level emission observed on the photoluminescence （PL） spectrum as well as high transparence of about 89% transmittance in visible light range.展开更多
基金the National Natural Science Foundation of China(No.52272009)the Henan Provincial Science and Technology Research Project(No.242102230151)+1 种基金the Henan Provincial University Science and Technology Innovation Team(No.25IRTSTHN009)the Key Scientific Research Projects of Colleges and Universities in Henan Province(Nos.24B560021,25B560020,25B560023)。
文摘This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.
基金Project(2006AA03Z413) supported by the Hi-tech Research and Development Program of China
文摘SnO2 nanoparticles with the average particle size of 5-30 nm were synthesized using SnCl4·5H2O as the precursor and NH3·H2O as the mineralizing agent by hydrothermal method.In the case of 1 kg/batch production,the effects of synthesis conditions including solution concentration,reaction temperature,pressure,time and pH value on the grain size,particle morphology and crystal structure of SnO2 were systematically studied.The particles were characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）.The results show that,the particle size can be well controlled in the range of 5-30 nm by adjusting the processing parameters such as reaction temperature and time when the crystal structure and particle morphology remain unchanged.The previous reports,the unusual dependences of the grain size of SnO2 on reaction temperature and time were found.The mechanism for such abnormal grain growth behavior was tentatively elucidated.
基金Supported by the Education Department of Zhejiang Province(20030625)SRF for ROCS,SEM(2003-14)the National Natural Science Foundation of China(50272059).
文摘The semiconductor TiO_(2)is the most important photocatalyst for the degradation of pollutants.Anatase TiO_(2)has a large band gap of 3.2 eV that requires powerful UV light to initiate the photocatalytic reactions.Many modifịcation methods such as metal ion doping,composite semiconductors and metal layer modification have been used to extend the light absorption of the catalyst to the visible light region but have little effect[1~4].Surface sensitization with dyes[5]is not practical in application as most dyes self-degrade easily.Therefore,the preparation of TiO_(2)with good wavelength response in the visible light region and high photocatalytic activity for pollutant degradation using natural sunlight is an important goal in TiO_(2)photocatalysis.
基金Project supported bythe Key Laboratory of Rare Earth Chemistry and Physics ,ChangchunInstitute of Applied Chemistry ,Chinese Academy of Sciences (R020202K)
文摘Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.
文摘LiCoPO4 micron-rods with an average diameter of about 500 nm and length of about 5 μm were synthesized by dispersant-aided hydrothermal method. Poly(n-vinylpyrrolidone) (PVP) was used as dispersant in the hydrothermal method. The starting solution and the concentration of dispersant have significant influences on the morphology of LiCoPO4,and the electrochemical performance is improved via controlling the particle size and morphology by the hydrothermal method. The cell using smaller particle LiCoPO4 as cat...
基金financially supported by the National Natural Science Foundation of China (Nos.51302322 and 21373273)the Open-End Fund for the Valuable and Precision Instruments of Central South University (No.CSUZC201613)+1 种基金the Open Foundation of Guangdong Provincial Key Laboratory for Technology and Application of Metal Toughening,Guangdong Institute of Materials and Processing (No.GKL201605)the Education Reform Project of Central South University (No.2016jy03)
文摘pH value is a key factor in the preparation of nano-sized TiO2 with hydrothermal method. Using Ti（SO4）2 as the titanium source, H2O2 as the complexing agent, NaOH and HCl as the pH value regulator, nano- sized TiO2 powder with various morphologies and sizes was synthesized. Changes in morphology, size and phase type with pH values of samples were characterized by X-ray diffraction （XRD） and transmission electron micro- scopy （TEM） measurements. Results show that under the present preparation conditions, TiO2 powder is an anatase phase with pH value less than 11, but is more likely to be a brookite phase with pH value more than 11. With the increase in pH value from 1 to 11 in hydrothermal envi- ronment, nano-sized anatase TiO2 gradually grows up in all directions. {001 }, { 101 } and { 100} groups of crystal plane are the exposed crystal planes of nano-sized anatase TiO2 for the （004）, （101） and （200） facets found in high-reso- lution TEM image. The photocatalytic performance of nano-sized TiO2 with different morphologies was com- pared by measuring their photocatalytic degradation rates for methylene blue under ultraviolet light. Results show that anatase TiO2 prepared under the alkalescenthydrothermal environment （pH = 9, 11） has a better pho- tocatalytic degrading performance. Different sizes and phases of nanoscaled TiO2 powders with different photo- catalytic performances can be prepared by the control of pH value of hydrothermal solutions.
基金financially supported by GRINM Science and Technology Innovation Fund (Nos. 2020DY0109 and 57222001)the Opening Project Fund of Materials Service Safety Assessment Facilities (No. MSAF-2021-001)Guangdong High Level Innovation Research Institute (No. 2021B0909050001)。
文摘Silicon is one of the most promising anode materials for lithium-ion batteries(LIBs), but it suffers from pulverization and hence poor cycling stability due to the large volume variation during lithiation/delithiation. The core-shell structure is considered as an effective strategy to solve the expansion problem of silicon-based anodes. In this paper, the double-shell structured Si@SnO_(2) @C nanocomposite with nano-silicon as the core and SnO_(2) , C as the shells is synthesized by a facile hydrothermal method.Structural characterization shows that Si@SnO_(2) @C nanocomposite is composed of crystalline Si, crystalline SnO_(2) and amorphous C, and the contents of them are 42.1wt%, 37.8 wt% and 20.1 wt%, respectively. Transmission electron microscope(TEM) observations confirm the double-shell structure of Si@SnO_(2) @C nanocomposite, and the thicknesses of the SnO_(2) and C layers are 20 and 7 nm. The Si@SnO_(2) @C electrode exhibits a high initial discharge capacity of 2777 mAh·g^(-1)at 100 mA·g^(-1)and an excellent rate capability of 340 mAh·g^(-1)at 1500 mA·g^(-1). The outstanding capacity retention is 50.2% after 300 cycles over a potential of 0.01 to 2.00 V(vs. Li/Li+) at 500 mA·g^(-1). The resistance of solid electrolyte interphase(SEI) film(Rf) and charge transfer resistance(Rct) of Si@SnO_(2) @C are 7.68and 0.82 Ω, which are relatively smaller than those of Si@C(21.64 and 2.62 Ω). It is obviously seen that the SnO_(2) shell can reduce the charge transfer resistance, leading to high ion and electron transport efficiency in the Si@SnO_(2) @C electrode. The incorporation of SnO_(2) shell is attributed to the enhanced rate capability and cycling performance of Si@SnO_(2) @C nanocomposite.
基金Project supported by the Nation Natural Science Foundation of China(51562025)Graduate Student Innovation Special Funds(YC2016-S085)
文摘The europium ions doped MMoO4 （M=Sr, Ba） nanophosphors were successfully synthesized via a facile hydrothermal method using isopropanol. The relationship between phosphor crystalline phase, morphology, photohtminescent properties and hexadecyl trimethyl ammonium bromide （CTAB） concentration, pH value in precursor solution was investigated. The results indi- cated that the morphology and photoluminescent properties were strongly influenced by CTAB concentration and pH value in precursor solution. In SrMoO4：Eu3＋ hosts, the phosphor surface tended to become smoother as the concentration of CTAB was increased; while particles tended to agglomerate as increasing pH value. The relative intensity ratio of charge transfer band to Eu3＋ characteristic emission peaks of MMoO4：Eu3＋ （M=Sr, Ba） was changed as CTAB concentration and pH value changed. The emission spectra of MMoO4：Eu3＋ （M=Sr, Ba） could be adjusted by CTAB concentration and pH value due to their impacts on the structure. It was im- portant that the different morphologies and photoluminescent properties of MMoO4：Eu3＋ （M=Sr, Ba） could be obtained by the facile hydrothermal method and modulated by changing CTAB concentration and pH value.
基金the financial support from the Ministry of Science and Technology,Taiwan(MOST 104-2218-E-033-006-MY2)
文摘NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, UV–visible（UV–vis） diffuse reflectance spectroscopy, and photoluminescence（PL） spectroscopy. The XRD patterns of the H-and S-samples showed peaks indexed to the pure phase of perovskite NaTaOand minor peaks assignable to TaNat various synthesis temperatures. Substitution of oxygen by nitrogen ions causes the light absorption of the H-and S-NaTaONsamples to be extended to the 600–650 nm region, thus making the samples visible-light active. The NaTaONsamples exhibited photocatalytic activity for Hand Oevolution from aqueous methanol and silver nitrate solutions under visible-light irradiation. The UV–vis and PL spectra of the Hand S-catalysts revealed the presence of cationic vacancies and reduced metallic species, which acted as recombination centers. These results demonstrated that the preparation method plays a critical role in the formation of defect states, thereby governing the photocatalytic activity of the NaTaONcatalysts.
基金supported by the Chinese Ministry of Science and Technology 973 Program(No. 2006CB705604)Science and Technology Commission of Shanghai Municipality(No.09XD 1401800)+1 种基金the National Natural Science Foundation(No.50578090)Shanghai Leading Academic Discipline Project(No.S30109)
文摘In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）. scanning electron microscope（SEM） and Brunauer-Emmett-Teller（BET）.The prepared TiO_2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested.Results show the prepared TiO_2 nanotube gas sensors responses to ethanol under dry condition at 450℃.This could be attributed to the fact that it had high porous morphology and a higher pore volume,which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover,the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H_2,CO,acetone.
基金supported by the National Basic Research Program of China (Grant No.2007CB613603)
文摘Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.
基金Project(51261015)supported by the National Natural Science Foundation of ChinaProject(1308RJZA238)supported by the Natural Science Foundation of Gansu Province,China
文摘Pure ZnS and Ni^2+-doped ZnS nanorods (Zn1-xNixS, x=0, 0.01, 0.03, 0.05 and 0.07, mole fraction,%) were synthesized by hydrothermal method. The effects of Ni2+ doping on the phase-structure, morphology, elemental composition and optical properties of the samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (EDS) and ultraviolet–visible spectroscopy (UV-Vis), respectively. The photocatalytic activity of Zn1-xNixS nanorods was evaluated by the photodegradation of organic dyes Rhodamine B (RhB) in aqueous solution under UV light irradiation. The results show that all samples exhibit wurtzite structure with good crystallization. The morphologies are one-dimensional nanorods with good dispersion, and the distortion of the lattice constant occurs. The band gap of Zn1-xNixS samples is smaller than that of pure ZnS, thus red shift occurs. Ni^2+-doped ZnS nanocrystals can enhance photocatalytic activities for the photodegradation of RhB. Especially, Zn0.97Ni0.03S sample exhibits better photocatalytic performance and photocatalytic stability for the decomposition of RhB.
基金financially supported by the National Natural Science Foundation of China (No. 51474028)the National Key Research and Development Program of China (No. 2017YFC0210301)+1 种基金China Postdoctoral Science Foundation (No. 2017M621034)the Science and Technology Benefiting Citizens Program of Ningbo, China (No. 2015C50058)
文摘Hydro-sodalites are zeolitic materials with a wide variety of applications.Fly ash is an abundant industrial solid waste,rich in silicon and aluminum,from which hydro-sodalite can be synthesized.However,traditional hydrothermal synthesis methods are complex and cannot produce high-purity products.Therefore,there is a demand for processing routes to obtain high-purity hydro-sodalites.In the present study,high-purity hydro-sodalite(90.2 wt%)was prepared from fly ash by applying a hydrothermal method to a submolten salt system.Samples were characterized by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetry and differential thermal analysis(TG–DTA),and Fourier transform infrared spectroscopy(FTIR)to confirm and quantify conversion of the raw material into the product phase.Purity of the samples prepared with an H2O/Na OH mass ratio of 1.5 and an H2O/fly ash mass ratio of 10 was calculated and the conversion process of the product phase was studied.Crystallinity of the product was influenced more by the Na OH concentration,less by the H2O/fly ash mass ratio.The main reaction process of the system is that the Si O ions produced by dissolution of the vitreous body in the fly ash and Na+ions in the solution reacted on the destroyed mullite skeleton to produce hydro-sodalite.This processing route could help mitigate processing difficulties,while producing high-purity hydro-sodalite from fly ash.
文摘High quality potassium hexatitanate whiskers were hydrothermally synthesized in one step under moderate temperature and pressure conditions. Effects of the titanium source and reaction conditions on the hydrothermal reaction rate, product phase component, and morphology of whiskers were investigated. The results show that the reactivity of hydrated titania, anatase TiO2, and rutile TiO2 with KOH decreases in turn, and with hydrated titania as titanium source, it is difficult to obtain potassium hexatitanate whiskers with good morphology. In contrast, uniform potassium hexatitanate whiskers with a length of 10-20 μm and a diameter of 200-700 nm were obtained using anatase TiO2 as titanium source. The investigation demonstrates that the initial KOH concentration, annealing temperature and time, molar ratio of K2O/TiO2, etc. significantly affect the morphology of the as-synthesized whiskers. The optimized synthesis condition is as follows： anatase as a titanium source 10 wt.% KOH solution; annealing temperature and time of 300℃ and 5 h, respectively; K2O/TiO2 molar ratio of 5, etc. A rhombic potassium hexatitanate was prepared under the optimum condition and the whisker grew along the [110] direction. The reaction mechanism was discussed.
基金This project is supported by National Natural Science Foundation of China(No.90207003) and Returnee Foundation of Dalian.
文摘Lead zirconate titanium solid-solution (PZT) thin films with variousthickness are synthesized on titanium substrates by repeated hydrothermal treatments. Young modulus,electric-field-induced displacement and the density of the PZT film are measured respectively.Bimorph- type bending actuators are fabricated using these films. The model, which is used toanalyze the driving ability of bimorph-type bending actuators by hydrothermal method, is set up. Itcan be seen that the driving ability of bimorph-type bending actuators can be greatly improved byoptimizing the thickness of PZT thin film and substrate from the theoretical analysis results. Themeasured values are expected to agree with the theoretical values calculated by the above model.
基金This work was supported in part by NSF of Guangdong Province,the Most Important Items of the Tenth Five-Year Plan of Guangdong Provincethe Project of Science and Technology Program of Guangdong Province+1 种基金the Project of Science and Technology Program of Guangzhou Citythe Maoming Science Technology Fund of Guangdong Province.
文摘The Ni(OH)2/SiO2 binary colloid was prepared using Ni(NO3)2.6H2O and (C2H5O)4SiO4 as starting materials and was used to form NiO/SiO2. composite powder by hydrothermal method and desiccant method in open air respectively. Multi-walled carbon nanotubes (MWCNTs) were synthesized respectively by chemical vapor deposition using the NiO/SiO2 catalyst prepared by different methods. The phase and morphology of the catalysts and the morphology, output yield and purity of MWCNTs were compared by XRD, TEM and SEM. The results show that the catalyst powder prepared by hydrothermal method, compared with that by desiccant method, is smaller, better dispersion and has stronger catalytic activity. Pure MWCNTs with smaller tube diameter and narrow range could be obtained at a high yield using that NiO/SiO2 powder prepared by hydrothermal method as catalyst.
基金financial support by the Open Project Program of the State Key Laboratory of Solid Lu-brication, Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences (0804)
文摘Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray powder diffraction （XRD）,field emission scanning electron microscopy （FESEM） and energy dispersive spectroscopy （EDS）.The influence of hydrothermal temperature,precursor solution concentration on the crystal and morphology of products were further studied.The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure.The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles.Furthermore,the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.
基金supported by the Open Fund(PLN0805) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University (SWPU),China
文摘Different morphologies of zinc oxide（ZnO）,including microrods,hexagonal pyramid-like rods and flower-like rod aggregates,had been synthesized,respectively,on glass substrates by controlling the reaction conditions（such as precursor concentration,reaction time and pH value） of hydrothermal method.The morphologies of the as-obtained ZnO were observed with scanning electron microscopy and transmission electron microscopy.Also,the crystalline natures of different ZnO crystals were analyzed with X-ray diffraction.The possible growth mechanism of ZnO crystals with different morphologies was discussed.
基金Project(2008A090300016) supported by Major Science & Technology Special Program of Guangdong Province,China
文摘Micaceous iron oxide （MIO） with a hexagonal flaky shape was prepared by hydrothermal method. The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution. The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments. Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L, pH value of 8, n（Fe2＋）/n（Fe3＋） of 0.1, mass of seed crystal of 1 g, reaction temperature of 260 ℃ and reaction time of 30 min are applied. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and selected area electron diffractometry （SAEM） were adopted to characterize the hydrothermal products prepared under optimal conditions. The results indicate that highly crystallized α-Fe2O3 hexagonal flakes, about 1.0-1.5 μm in diameter and 0.1 μm in thickness, are prepared. Furthermore, the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints （ISO 10601--2007）.
基金supported by the National Natural Science Foundation of China(Grant No.50871046)the Foundation of National Key Basic Research and Development Program(No.2010CB631001)the Program for Changjiang Scholars and Innovative Research Team inUniversity
文摘ZnO film with claviform structure was synthesized on quartz substrates through a hydrothermal method at 90℃. The microstructure of the film is composed of clusters of submicrometer rods, which therefore endues the film with good superhydrophobicity. Meanwhile, the film with such tanglesome structure also shows highly crystalline quality testified by a strong ultra-violet （UV） emission and very low deep-level emission observed on the photoluminescence （PL） spectrum as well as high transparence of about 89% transmittance in visible light range.
