Papers by Keyword: High Crystallinity

Abstract: Zeolite P was synthesized for hydrothermal route at crystallization temperature of 95°C and crystallization time of 7h, using“acid-treated stellerite-NaOH-NaAlO₂-H₂O” as precursor, with different molar ratios n (SiO₂/Al₂O₃), n (Na₂O/SiO₂) and n (H₂O/Na₂O). The as-fabricated samples were characterized by scanning electron microscopy, X-ray diffraction, FT-IR techniques. The result shows that: the crystal structure of zeolite P has been determined in the tetragonal crystal system, lattice constants are 10.049Å,10.047 Å and the crystallinity of zeolite P is 97%. Influences of synthetic parameters were investigated systematically to achieve high quality pure zeolite P phases. Moreover, this morphology and high crystallinity control approach might be further extended to the synthesis of other zeolite and used in industry, agriculture, environmental protection and biotechnology industries.

Abstract: N-doped mesoporous TiO2 with high surface area and crystallinity were synthesized by sol-gel method using polyacrylamide (PAM) and polyethylene glycol (PEG) as the complex templates. The resulting materials were characterized by XRD, TEM, N2 adsorption-desorption, and UV-Vis spectroscopy. It is found that when the weight ratio of PAM and PEG is 1:4, the sample, prepared at 600 °C in nitrogen and at 500 °C in air, is anatase phase and has high surface area and crystallinity. The particle size and pore size of the sample are about 10 nm and 17 nm respectively. Compared with that of the undoped mesoporous TiO2, the absorption band edges of N-doped samples exhibit an evident red-shift. The results of the photocatalytic degradation of methyl orange (MO) show that N-doped sample appears to have higher photocatalytic activity under visible light than undoped sample.

Abstract: A simple approach to the in situ deposition of well-crystallized SnO₂ nanocrystals on the surface of multiwalled carbon nanotubes (MWCNTs) in the ethanol solution system of SnCl2 was presented in this paper. The well-crystallized SnO₂ nanocrystals with small and uniform crystal size (4~5 nm) can be tightly and homogenously coated on the outside surface of the MWCNTs entirely. The prepared nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen BET measurements. It is found that the hydrothermal reaction plays an important role for the crystal growth of the SnO₂ nanocrystals on the surface of MWCNTs, and the crystallinity of the SnO₂ nanocrystals can be controlled by varying the pH value or the hydrothermal reaction time. It is found that a unique structure of leaf-like SnO₂ nanosheets hanging on the MWCNTs was obtained when using water as the solvent of SnCl₂ instead of ethanol. The gas sensing performance of the SnO₂/MWCNTs nanocomposites was also investigated.