Papers by Keyword: Solvothermal Synthesis

Abstract: Flower-like TiO₂ hierarchical structures were synthesized by a solvothermal strategy using tetrabutyl titanate as the titanium source. The obtained flower-like TiO₂ hierarchical structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area analysis, Raman spectroscopy and energy-dispersive spectroscopy (EDS). Results show that the flower-like hierarchical structures are composed of anatase titanium dioxide. TiO₂ nanowires are first formed by the self-assembly of nanocrystals with a diameter of 20 nm, and then several TiO₂ nanowires produce a petal-like structure. Finally, flower-like TiO₂ hierarchical structures with a diameter of 2 ~ 2.3 μm are assembled by these petal-like structures. The electrochemical properties of the flower-like TiO₂ hierarchical structures were studied by using these hierarchical structures as the anode material in a lithium-ion battery. The flower-like TiO₂ hierarchical structures have an initial discharge capacity of 473.9 mAh/g at a current density of 100 mA/g and an initial discharge capacity of 244.4 mAh/g at a current density of 2 A/g in the potential range of 0.01~3 V. The photocatalytic properties of the flower-like TiO₂ hierarchical structures were studied by degrading methyl orange (MO) solution under ultraviolet (UV) light irradiation. When used as a photocatalyst, the degradation rate of MO is 95.8% after 40 min of UV irradiation, showing that the flower-like TiO₂ hierarchical structures have excellent photocatalytic activity.

Abstract: In this paper, the time effect of hydrothermal synthesis on YF₃ morphology particles is considered. The work was carried out on X-ray-excited YF₃:Ce³⁺ phosphors. The synthesis was carried out by the hydrothermal method, since it avoids high temperatures leading to particle agglomeration. The first stage of research consisted in identifying the most favorable medium for obtaining the required phase and size - water or organic matter (ethylene glycol and ethanol). Research has shown that ethylene glycol has all the advantages: it prevents agglomeration, allows us to get the required phase. Hydrothermal synthesis of YF₃ samples to determine the optimal synthesis time was carried out according to the same scheme - in an organic medium of ethylene glycol without using stabilizers for 4, 8, 12, 16, 20 hours. Our study showed that it is possible to obtain a YF₃ sample that meets the necessary requirements (including nanoscale) within 16 hours, moreover, without the use of stabilizers. In parallel with the study of the synthesis duration, an experiment was carried out on the effect of various stabilizers on the properties of the YF₃:Ce³⁺ phosphors (5%). The synthesized nanophosphors possessed effective X-ray luminescence with a maximum in the region of 300 nm, which makes it possible to use them in the composition of preparations for PDT.

Abstract: V₂O₅ hollow microspheres were synthesized by a one-step solvothermal method, with the assistance of PVP as the soft template, ethylene glycol (EG) as the solvent, and vanadium (iii) acetylacetonate (acac) as the metal-ions source. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM). The size of V₂O₅ hollow microspheres, which can be easily tuned by using PVP of different molecular weights, was about 2.5μm, 4.5μm and 6μm when using PVP-K17, PVP-K30 and PVP-K60 as the template, respectively.

Abstract: The construction, crystal structure and properties and potential application of metal imidazoledicarboxylate frameworks have currently attracted considerable attention. A novel open-framework Lanthanide imidazoledicarboxylate, [Tb (HpyimdC)(C₂O₄)_0.5(H₂O)]·(H₂O)₃ (compound 1), was constructed from 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylate (H₃PyImdc) and Oxalate coordinated with lanthanide under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that compound 1 crystallized in the monoclinic space group C2/c (No. 15). Oxalate chelated with Tb to form a one-dimensional zigzag chain, H₃pyimdc with selective nitrogen−oxygen chelating site, constructed these chains into metal organic frameworks featuring extra-large channels deposited by guest molecules. Further characterizations for compound 1 have been performed, including X-ray powder diffraction, IR Spectrum and elemental analysis. Synthesis, crystal structure and structural characterizations for 1 were reported in this paper.

Abstract: Theoretical studies predicted that doping graphene with nitrogen can tailor its electronic properties and chemical reactivity. We develop here a novel method for synthesis N-doped graphene via solvothermal synthesis process with urea as both reductant and nitrogen sources. The resulting N-doped graphene were characterized by various methods (UV-vis spectra, SEM and XPS). XPS analysis shows a predominant graphitic C 1s peak at ca. 285 eV, an O 1s peak at ca. 532 eV and N 1s peak at ca. 410 eV. Moreover, the atomic ratio of N/C is 5.0% for N-doped graphene, demonstrating nitrogen species have been successfully incorporated into N-doped graphene.

Abstract: nanomelamine phosphate (NMP) flame retardant was synthesized by means of a solvothermal method, and was characterized by Fourier transform infra-red spectroscopy, X-ray diffraction, and scanning electron microscopy. Effects of reaction temperature and reaction time on the morphology of reaction products were investigated. It was observed that the morphology of the products changes greatly as reaction temperature or reaction time changes.

Abstract: A novel zinc organophosphonate was synthesized under solvothermal conditions by using [piperazine-1,4-diyldi (methylene)] bis (phosphonic acid) as a organic ligand. Single-crystal X-ray diffraction analysis reveals that compound 1 crystallized in the triclinic space group P-1 (No. 2). Compound 1 formulated as Zn (O₃PCH₂NHC₄H₈NHCH₂PO₃)·H₂O. Compound 1 featured a 3D open-framework. Notably, the structure of compound 1 featured one-dimensional channel in the [00 direction. Water molecules were located in these channels. Further characterizations of compound 1 have been performed, including X-ray powder diffraction, IR, ICP and CHN analyses.

Abstract: Nanocrystalline silver selenide (Ag₂Se) with an average diameter of 100 nm were prepared by a facile solvothermal method. X-ray energy dispersive (EDS) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies confirmed that the products were pure Ag₂Se. Room-temperature powder X-ray diffraction (XRD) measurements indicated that the as-prepared Ag₂Se nanocrystals exhibit a metastable tetragonal polymorphic phase, rather than the common orthorhombic phase at room temperature. The variable-temperature XRD and differential scanning calorimetry (DSC) thermal analysis techniques were used to investigate the phase change behaviors of the tetragonal Ag₂Se nanocrystals, and the results showed that the low-temperature tetragonal phase transforms to the high-temperature cubic phase at about 106 °C. This transition temperature is lower by ~30 °C than the orthorhombic-cubic transition temperature (133140 °C) previously reported for Ag₂Se. Meanwhile, two exothermic peaks, loaded at 61 and 89 °C, respectively, were detected in the cooling DSC scan for the cubic to tetragonal phase transition, and the reason was discussed.

Abstract: Denser, solvothermally synthesized KNbO₃ (KN) / BaTiO₃ (BT) composites with heteroepitaxial interfaces were prepared using the barium titanate powder with a wide particle size distribution. The relative density was 68 - 80 %, which was larger than that of the composites prepared using the barium titanate powder with a narrow particle size distribution. The dielectric constant was 300 450 and it was maximized at the KN/BT molar ratio of 0.5. The origin was discussed with the microstructure and crystal structure.

Abstract: Nano-size ZnO of one dimensional structure was prepared by solvothermal synthesis through dissolution-crystallization mechanism and characterized by TEM and XRD. Moreover, photocatalytic degradation rate of dye Rhodamine B (RhB) at the present of nano-size ZnO were carried out, and the results indicated that the nano-size ZnO prepared by such a method has excellent photocatalytic properties.