Yude Wang

Preparation of nanocrystalline metal oxide powders with the surfactant-mediated method

Abstract Nanocrystalline metal oxides (ZnO, NiO, and SnO2) powders with an average particle diameter of 18–55 nm have been successfully prepared with the surfactant-mediated method. The cationic surfactant (cetyltrimethylammonium bromide, CTAB) and the hydrous metal chlorides (ZnCl2·2H2O, NiCl2·6H2O, and SnCl4·5H2O) appear to be the good candidates for obtaining a high yield of nanoparticles. The resultant products have been characterized by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The resulting powders are highly crystalline and largely monodisperse oxide particles. The surfactant-mediated method turned out to be suited for the preparation of the nanocrystalline oxide powders. Through this method, it is possible to obtain nanocrystalline metal oxide powders.

Preparation and characterization of SnO2 nanoparticles with a surfactant-mediated method

Using a surfactant-mediated method, tin dioxide nanoparticles with a high surface area were generated within the template of the cationic surfactant (cetyltrimethylammonium bromide) micelle assembly from the hydrous metal chloride (SnCl4 ? 5H2O). The as-synthesized product was amorphous and transformed into crystalline calcined at 500?C for 2 h, and exhibited a higher Brunauer?Emmet?Teller surface area of 69.2 m2 g?1. The resulting particles were highly crystalline and largely monodisperse oxide particles in the nanometre range (15?25 nm). Thermogravimetric analysis, x-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy were used to characterize the final products.

Preparation and characterization of MnOOH and β-MnO 2 whiskers

Abstract MnOOH and β-MnO 2 whiskers are obtained for the first time in our work. MnOOH whiskers are chemically synthesized in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The product is obtained under extremely low surfactant concentrations under basic conditions, using MnSO 4 ·H 2 O as the manganese source and ethylamine as the alkali source. After the subsequent heat treatment of MnOOH at 300 °C for 1 h, β-MnO 2 whiskers retaining the similar morphologies are obtained. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetry analysis (TGA) are used to characterize the products.

Synthesis of mesoporous structured material based on tin oxide

Abstract Mesoporous structured tin oxide with high specific surface area was synthesized under acidic conditions at ambient temperature in this study. The synthesis of this material was accomplished using a cationic surfactant (cetyltrimethylammonium bromide: CH 3 (CH 2 ) 15 N + (CH 3 ) 3 Br − ) as the organic supramolecular template and the hydrous tin chloride (SnCl 4 ·5H 2 O) and NH 4 OH as the inorganic precursor and counterion source. X-ray diffraction, thermogravimetric analysis and transmission electron microscopy have been used to characterize the mesostructures formed at room temperature as well as calcined at different temperature. The synthesis procedure strongly influenced the formation of the mesophase. The pore diameters and the surface areas of materials, evaluated from the N 2 -sorption isotherms, indicate average pore diameters of about 22 and 24 A and surface areas about 368 and 343 m 2 /g for calcination at 300 and 350 °C respectively. The formation of the tin oxide mesostructured material was proposed due to the presence of the hydrogen-bonding interactions between supramolecular template and inorganic precursors Sn 4+ and OH − , which were supposed to self-assemble around the cationic surfactant molecules.

Synthesis and characterization of amorphous TiO2 with wormhole-like framework mesostructure

Abstract Using neutral amine surfactant (dodecylamine) as an organic template and neutral inorganic material (tetrabutyl titanate) as a precursor, amorphous TiO2 with wormhole-like framework mesostructure was synthesized with the variation of surfactant-to-Ti alkoxide ratios. Powder X-ray diffraction (XRD), thermogravimetric analysis, Fourier transformed infrared spectra, transmission electron microscopy (TEM), nitrogen adsorption–desorption, and X-ray photoelectron spectroscopy (XPS) have been used to characterize the TiO2 mesostructure. The interaction between surfactant and titanium dioxide was displayed by XPS. The samples exhibit a wormhole-like framework from XRD patterns and TEM images, and high surface area (221 m2/g) for the sample calcined at 450 °C for 2 h. The formation of the titanium oxide mesostructure is proposed to be due to the presence of the interactions between surfactant head group and inorganic precursors prior to hydrolysis, and the condensation under condition favorable for liquid crystal formation.

Neutral templating route to mesoporous structured TiO2

A neutral templating route for preparing mesoporous structured TiO2 with high surface area is demonstrated based on self-assembly between a neutral amine surfactant (dodecylamine) and neutral inorganic precursor (tetrabutyl titanate). X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron micrographs (TEM) have been used to characterize the mesostructure that forms at room temperature as well as the calcined materials. The pore diameters and the surface areas of materials, evaluated from the N2-sorption isotherms, indicate average pore diameter of about 29.8 A and surface areas about 246 m2/g for calcination at 300 °C.

Synthesis of mesostructured SnO2 with CTAB and hydrous tin chloride

Abstract Mesostructured SnO 2 was synthesized using a cationic surfactant (cetyltrimethylammonium bromide, CTAB) as the organic supramolecular template and the hydrous tin chloride (SnCl 4 ·5H 2 O) and NH 4 OH as the inorganic precursor and counterion source under acidic conditions and room temperature. The resultant products have been examined with X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The formation of the tin oxide mesostructured material was proposed due to the presence of the hydrogen bonding interactions between supramolecular template and inorganic precursors Sn 4+ and OH − , which was supposed to self-assemble around the cationic surfactant molecules.

Formation of lamellar manganese oxide mesophases under several different synthetic conditions

Abstract In our work, manganese oxide mesophases with lamellar nanostructures were chemically synthesized using simple materials (MnSO4·H2O and NaOH) as the inorganic precursors under extremely low surfactant (cetyltrimethylammonium bromide, CTAB) concentration. Several factors that were influential on the preparation of mesostructured manganese oxide were investigated, including ageing temperature, addition sequence, stirring time and strength and ageing pressure. Some explanations to those obtained results were given in this article.

Effects of polarization on crystallization of calcium phosphate

Abstract The acceleration effects of polarized lead zirconate titanium (Pb(Ti,Zr)O 3 , PZT) on the crystallization of calcium phosphate were demonstrated when PZT plates were immersed in saturated solutions of hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ). Moreover, it is indicated that polarization also had influences on the orientation of the deposited crystals because crystalline layers of OCP (Ca 8 H 2 (PO 4 ) 6 ·5H 2 O) were found on the negatively charged surfaces of PZT.