Papers by Keyword: Hydrothermal Method

Abstract: Al-doped ZnO (AZO) powers with a novel rice-like morphology have been successfully synthesized through a simple and efficient hydrothermal approach, the products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy-dispersive X-ray analyzer and transmission electron microscopy (TEM). It showed that all the samples presented an hexagonal wurtzite structure of high crystallinity, and the microstructure was composed of numerous dumbbells. Furthermore, the heater gas sensors were fabricated and an investigation of gas sensing properties has been conducted. The sensors showed good selectivity to ethanol comparing with NH₃, SO₂, CO and HCHO and possible mechanism was discussed. The Sensors based AZO powers exhibited high response values, reproducible response-recovery to ethanol 50-1800 ppm at 332°C.

Abstract: In this paper, Ag₂S nanomaterials with good morphology and crystalline have been prepared successfully by a hydrothermal method with AgNO₃ and (CH₂)₂CS as raw materials, SUDEI and PVP as surfactant, respectively. The photo-thermal transformation performance of the nanomaterials was studied. It was found that the Ag₂S nanomaterials had a good photo-thermal property and the corresponding photo-thermal transformation efficiency could reach up to 63%.

Abstract: In this paper,europium doped zinc oxide nanoparticles were prepared by Zn (CH₃COO)₂, Eu (NO₃)₅·6H₂0,NaOH,PEG2000 and Citric acid using hydrothermal method. The prepared powder was used for photocatalytic degradation, in which the influence ofreaction temperature, reaction time, illumination conditions as well as the doping ratio on the effect of photocatalytic oxidation were throughly investigated. Analytical methods, such as XRD, SEM and EDS were utilized in this study for characterization of the prepared powder. Results showed that Europium-doped zinc oxide with a 3% doping ratio reached optimal photocatalytic oxidation effect when the hydrothermal temperature was 160°C and hydrothermal time was 6 hours. By utilizing the prepared powder under optimal conditions, the decolorization rate of pharmaceutical wastewater reached 38.8% after treatment of 365nm UV irraditation for 150min, and the degradation rate of COD reached 57.5%.

Abstract: One-dimensional orthorhombic NaNbO₃ long rods were successfully prepared by combining a traditional hydrothermal method with the post-heat treatment. In the hydrothermal reaction process, sandia octahedral molecular sieves (SOMS) were synthesized at 160°C using Nb₂O₅ and NaOH as the initial reactants. Then, the effects of different post-heat treatment conditions on the morphology and crystallinity of product were investigated. Results showed that post-heat temperature could promote the crystal of the product to form orthorhombic NaNbO₃, and the axis of the long rod ran along the [001] direction of NaNbO₃ orthorhombic unit cell. Our study may provide a new approach for the preparation and investigation of one-dimensional alkali niobate photocatalytic materials and template grain for textured alkali niobium.

Abstract: The study of dye-sensitized solar cells (DSCs) based on nanocrystalline films of high band gap semiconductors is a progressive field of research that is being carried out by scientists in a wide range of laboratories. To improve the conversion efficiency of the DSCs, the SnO₂ nanorots photocurrent, the effect of controlling concentration on the properties of SnO₂ nanocrystalline were investigated via the hydrothermal method, and characterized by XRD, HRTEM, BET and Absorption spectrum. Though analysis the results, the conclusion is shown the pure SnO₂ is preparation, the prepared SnO₂ nanocrystalline under 0.05mol/L shows the particle-shape crystalline, the surface area of SnO₂ nanocrystalline is 102.1683m²/g. The prepared SnO₂ nanocrystalline under 1mol/L the fiber-shape crystalline, the surface area of SnO₂ nanocrystalline is 79.7591m²/g. The absorbance of SnO₂ nanocrystalline shows the strong absorption in the ultraviolet ray range, the absorbance of synthesized SnO₂ nanocrystalline under the concentration of SnCl₄ solution for 1mol/L shows the higher value.

Abstract: In this paper, spherical nanohydroxyapatite was synthesized by hydrothermal method. During the synthesizing process, different amount of L-lysine template was added with the hydrothermal temperature 185 °C and the time 25 h. The products were characterized by using FTIR, XRD and TEM. Results showed that the rod-like nanohydroxyapatite changed its granule morphology into spherical obviously after adding L-lysine. Spherical nanohydroxyapatite was synthesized with mean particle size about 25 nm.

Abstract: The study of dye-sensitized solar cells (DSCs) based on nanocrystalline films of high band gap semiconductors is a progressive field of research that is being carried out by scientists in a wide range of laboratories. To improve the conversion efficiency of the DSCs, the SnO₂ nanorots photocurrent is prepared via the hydrothermal method, and characterized by XRD, FESEM, BET and Absorption spectrum. Though analysis the results, the conclusion is shown the pure SnO₂ is preparation, the SnO₂ nanocrystalline both shows the single phase that SnO₂ from the sule solution to kalin solution. The prepared SnO₂ nanocrystalline under pH=3 shows the particle-shape crystalline, the surface area of SnO₂ nanocrystalline is 86.3412m²/g. The prepared SnO₂ nanocrystalline under pH=7 shows the short rod-shape crystalline, the surface area of SnO₂ nanocrystalline is 58.3408m²/g. The absorbance of SnO₂ nanocrystalline shows the strong absorption in the ultraviolet ray range, the absorbance of synthesized SnO₂ nanocrystalline under pH=11 shows the highest value.

Abstract: Single-crystal hematite (α-Fe₂O₃) nanoeggs are firstly synthesized using an anion-assisted hydrothermal method. By adjusting the ratios of phosphate to ferric ions, we are able to produce an egg-like nanostructure. And then α-Fe₂O₃ nanoeggs are converted to magnetite (Fe₃O₄) by a chemical reduction while preserving the same morphology. The characterizations of Fe₃O₄ nanoeggs indicate Fe₃O₄ nanoeggs with uniform size and shape are successful synthesized. Our results provide an easily scaled-up method for preparing tailor-made large-sized iron oxide nanoeggs that could meet the demands of a variety of applications.

Abstract: TiO₂ films were prepared on glass and 316L stainless steel (316L SS) using hydrothermal method. The microstructures of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It indicated that the films crystallized as anatase phase with mirror-like surface morphology. The optical properties of the TiO₂ film were studied by Ultraviolet Visible Spectroscopy (UV-Vis). The results showed that the film was transparent in visible range. The cut-off point of the sample was red-shifted after annealed treatment. The corrosion resistance of the film was evaluated by using Tafel polarization curve in simulated body solution. The corrosion current density was decreased from 8.556 μA/cm² (316L SS) to 1.421 μA/cm² (TiO₂ film/316L SS). While, the corrosion potential was increased from-0.402 V (316L SS) to-0.325 V (TiO₂ film/316L SS). The 316L SS with TiO₂ film has better corrosion resistance.

Abstract: Multiferroic BiFeO₃ powders were synthesized by two methods: sol-gel process and hydrothermal method. The synthesized powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and particle size distribution analysis. The results obtained by XRD, which is consistent with 86-1518 JCPDS card, show that powders prepared by hydrothermal method are composed of the single phase with the trigonal structure (perovskite-type). It can be found by particle size distribution analysis that the particle size of the samples prepared by sol-gel process is finer and more uniform than that of the samples synthesized by the hydrothermal method. The SEM images of samples depicts that the synthesized BiFeO₃ powders are united and the average grain size of hydrothermal processed samples is significantly large as compared to the sol-gel derived sample.