Yanqiu Jiang's research while affiliated with Jilin University and other places

The crystal and hydrophobic zinc borate (Zn2B6O11▪3H2O) nanodiscs were successfully prepared by a wet method using Na2B4O7▪10H2O and ZnSO4▪7H2O as raw materials in situ aqueous solution, and oleic acid as the modifying agent. The microstructures and morphology of the as-obtained samples were studied by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) and thermogravimetric analysis (TGA). The measurement of the active ratio indicated that Zn2B6O11▪3H2O samples were hydrophobic. It had been found that the as-prepared materials displayed nanodisc morphology with average diameters from 100 to 500nm and the thicknesses about 30nm. Moreover, the friction coefficient of the base oil was decreased by the addition of hydrophobic zinc borate nanodiscs.

The anatase titania (TiO2) nanocrystals with an average particle size of 7 nm were prepared by a new method of sol–gel process using titanium n-butoxide (Ti(OC4H9)4) as raw materials, acetic acid (HAc) as a modifier, and ammonium chloride (NH4Cl) as solid substrates. The hydrous TiO2 particles were deposited onto the surface of NH4Cl nanoparticles during hydrolysis of Ti(OC4H9)4. When the dry gel was calcined at lower temperature (250 °C), the hydrous TiO2 particles dehydrated and crystallized on the surface of NH4Cl nanoparticles, and finally, thermal dissociation of NH4Cl in this process leads to the formation of the pure titania product. The samples were characterized by XRD, TEM, and TGA. The results indicate that the thermal dissociation of NH4Cl can control the particle size and inhibit the agglomeration of anatase TiO2 in the calcining process and simultaneously enhance phase transformation from amorphous TiO2 to anatase phase.

Hydrophobic BaSO4 nanoparticles were successfully produced via a one-step process through precipitation reaction in aqueous solution of BaCl2 and (NH4)2SO4 with octadecyl dihydrogen phosphate (n-C18H37OPO3H2, ODP) as a modifying agent. The ODP was used to control the BaSO4 particle size and to modify the surface property of the particles produced from the precipitation. Measurements of relative contact angle and active ratio indicated that BaSO4 samples were hydrophobic. The samples were characterized by using field emission scanning electron microscope, transmission electron microscopy, X-ray diffraction, infrared analysis, thermogravimetric analysis and energy dispersive X-ray analysis. The results suggested that the hydrophobic property was attributed to presence of a thin layer of barium alkyl phosphates, which was formed and coated onto the surface of BaSO4 particles during the reaction process. The thin films at the surface of the BaSO4 modified the surface property and control the particle size and morphology.

A series of well-defined Ti-Si oxide composite spheres with hollow interior and porous shell wall were constructed through a complicated emulsion/interface method involving O/W/O structure present in the reaction system. The alternate Ti precursor of Ti ion solution (TIS) favors the composition homogeneity in the composite sphere shell by overcoming the mismatch hydrolysis ratio of the commonly chosen precursors, which is revealed by the fort-nation of Ti-O-Si bonds in SiO2 skeleton through XRD, Raman, Fr-IR, UV-vis analysis. This strategy is expected to extend to other composite preparation containing titanium composition. The resultant hollow Ti-Si oxide composite spheres from the emulsion droplets involving sacrificial organic cores exhibit variable sphere diameter in the range of ca. 10-500 mu m and tunable porous structure in sphere shell wall by deliberate control of the synthesizing parameters. The sleek inner and outer surfaces of the composite spheres proved by the broken ones originate from the sharp interface between organic and aqueous medium along with the existence of the non-ionic surfactant. (c) 2005 Elsevier B.V. All rights reserved.

The hollow SiO2/Al2O3 spheres with uniform mesopores in the shell wall have been successfully synthesized by a sol–gel process in an oil/water/oil (O/W/O) microemulsion. The intact hollow spheres are obtained by washing the as-synthesized solid produces with boiling water to remove the organic components. A large amount of silanol groups are retained in the hollow spheres by this facile route without calcination, and the possible agglomeration of the spheres and collapse of hollow structures are effectively avoided. The diameter and shell thickness of the spheres are measured by scanning electron microscope (SEM) and transmission polarized light microscope, which are ca. 10 and 2 μm, respectively. TEM image and N2 adsorption–desorption isotherms suggest that uniform mesopores are present in the shell wall of hollow SiO2/Al2O3 spheres after treatment with boiling water. 27Al NMR spectrum indicates almost all of aluminium species of hollow SiO2/Al2O3 spheres are in the four-coordinated environment.

A novel approach was employed in the synthesis of high-dispersed anatase titania (TiO2) nanocrystals by sol–gel process with NH4NO3 (AN) as solid substrates. Further calcination was conducted after the hydrous TiO2 nanoparticles were adsorbed onto the surface of AN particles. The products were investigated by TGA, XRD, and TEM. The results indicated that AN was melting and decomposing during the calcining process, which was very important to inhibit the agglomeration of anatase TiO2 nanocrystals. The highly dispersed anatase TiO2 nanocrystals were in needle-shape having lengths about 16–20 nm and diameter of 6–9 nm.

Stable hollow ZrO2–SiO2 spheres with mesopores in the shell wall have been successfully synthesized by a sol–gel process in an oil–water–oil microemulsion. The samples were characterized by transmission polarized light microscopy, SEM, TEM, and N2 adsorption–desorption isotherms. The characterization results indicate that a large number of mesopores are present in the shell wall of the calcined hollow ZrO2–SiO2 spheres, and that the diameter and shell thickness are ca. 50 and 15 µm, respectively. The hollow spheres exhibit high thermal stability and remain intact spherical structures even after calcination at 550 °C for 8 h. In the cracking reactions of cumene and 1,3,5-triisopropylbenzene the sulfated hollow ZrO2–SiO2 spheres show very high catalytic activities. Especially, the higher catalytic activity of 1,3,5-triisopropylbenzene cracking suggests the potential application in cracking of bulky molecules. A possible formation mechanism of hollow spheres of binary composite oxide is also proposed.

BaSO4 nanoparticles with an average particle size of 24.3 nm were prepared by the precipitation method using (NH4)2SO4 and BaCl2 as raw materials, and a water–alcohol solution as the reaction medium. The samples were characterized by photon correlation spectroscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis and infrared analysis. The results indicate that the BaSO4 powder sample has few mesopores and can self-diffuse in water, thus forming a suspension with enhanced stability and longevity. The preparation conditions that influenced the properties of the product were investigated and the mechanism of synthesis was also discussed. Adding ethanol during the preparation process can control the growth of the particles, and washing the precipitates in ethanol can prevent the particles from aggregating during the drying process. The powders are completely dried and treated at 200 °C to get rid of any remaining water in order to avoid subsequent aggregation of the particles. The samples can then be preserved for a long period. Ethanol combined with BaSO4 forms a film through hydrogen bonding. The hydrogen bonds and mesopores trigger self-dispersal of the BaSO4 powder in water.

Hollow silica nanoparticles were synthesized with incorporation of silanol groups (SiOH) onto polymer particles in dispersion polymerization and the polycondensation reaction of tetraethyl orthosilicate (TEOS) exclusively took place at the particles surface in the presence of ammonia following the so-called Stöber process and the silica-coated polymer powers were calcined at 800 °C. The diameters of hollow silica spheres are found to be very close to the original diameter and the average pore diameter is less than 100 nm. Moreover, the hollow silica nanoparticles have uniform aperture, do not agglomerate and collapse.

Stable hollow spheres of Si/Al composite oxide were synthesized by sol–gel process in o/w/o (oil/water/oil) microemulsion with PEG as the additive. The images of optical microscope and scanning electron microscope (SEM) showed that the spheres were consisted of hollow structure with the uniform sphere size of about 10 μm and shell thickness of about 3 μm. Furthermore, from transmission electron microscope (TEM), we clearly observed many worm-like pores in the shell of spheres. It was interesting to first find that the pore sizes in the shell of spheres can be controlled by the chain length of PEG. The hollow spheres also exhibited good thermal stability and they could maintain the complete structure even after calcination under 650 °C for 8 h.