Lanthana-doped mesoporous TiO2 nanoparticles with high specific surface area and thermal stable anatase wall was synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting materials were characterized by XRD, FESEM, TEM, FT-IR spectroscopy, and nitrogen adsorption. The as-synthesized mesoporous doped TiO2 nanoparticles have mean diameter of 20nm with mean pore size of 2.2nm. The specific surface area of the as-synthesized mesoporous nanosized doped TiO2 exceeded 460m2/g, and that of the samples after calcination at 500℃ still have 243m2/g. Compared with undoped sample and P25, the lanthana-doped mesoporous TiO2 nanoparticles show better activities on the oxidation of rhodamine B (RB). The large surface area and more active sites for combining with RB due to the present of lanthanum ion can explain the high photocatalytic activity of lanthana-doped mesoporous TiO2 nanoparticles.

Mesoporous titania nanoparticles with high specific surface area and thermal stable anatasewallwas synthesized from surfactant laurylamine hydrochloride (LAHC) and inorganic precursor Ti(SO4)2. The as-synthesized and calcined materials were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron micrographs, Fourier transform infrared spectroscopy and thermogravimetric analysis. The obtained mesoporous TiO2 nanoparticles have mean diameter of 25.5 nm. The specific surface area of the mesoporous nanosized TiO2 calcined at 400℃ exceeded 189m2 g−1, and that of the samples after calcinations at 500℃ still have 151m2 g−1. The obtained anatase mesoporous TiO2 nanoparticles show relative high thermal stability.

Cerium-doped mesoporous TiO2 nanoparticles with high surface area and thermal stable anatase wall were synthesized via hydrothermal process in a cetyltrimethylammonium bromide (CTAB)/Ti(SO4)2/Ce(NO3)4/H2O system. The obtained materials were characterized by XRD, FESEM, HRTEM, FTIR spectroscopy, nitrogen adsorption and DRS spectra. Experimental results indicated that the doping of cerium not only increased the surface area of mesoporous TiO2 nanoparticles, but also inhibited the mesopores collapse and the anatase-to-rutile phase transformation. Moreover, the undoped, doped anatase mesoporous nanoparticles exhibit higher photocatalytic activity than commercial photocatalyst (Degussa, P25), but the maximum photodegradation rate corresponds to the undoped mesoporous TiO2 nanoparticles. The lower photocatalytic activities of cerium-doped samples compared with undoped one may be ascribed to that the doped cerium partially blocks titania's surface sites available for the photodegradation and absorption of Rhodamine B (RB).

Nanocrystalline alumina powders were prepared by combustion synthesis using glycine as fuel and nitrate as an oxidizer. The effect of the pH values in the precursor solutions on crystallite sizes, surface areas and morphologies of the synthesized alumina powder has been investigated by X-ray diffractometry, thermal analysis, nitrogen adsorption-desorption, and transmission electron microscopy. With decreasing the pH values in the precursor solutions, the obtained materials could be modified from segregated nanoparticles (pH 10.5) to aggregates of nanoparticles (pH 6.0), and finally to a flaky morphology (pH 2.5). The rates of decomposition, the interaction of coordination as well as the hydrogen bonding of the glycine and the Al-hydroxides species at different pH values were found to be responsible for the generation of flake and/or segregated nanoparticles during auto-ignition reactions. The as-prepared combustion ashes were converted into pure nanocrystalline alumina after calcination at elevated temperatures. The specific surface areas of the products calcined at 800 8C ranged from 96 to 39 m2/g with the pH decreased from 10.5 to 2.5.

Titania was synthesized from laurylamine hydrochloride (LAHC) and Ti(SO4)2 under different acidic conditions. The effect of acidity on the structural and textural evolution of titania has been investigated by X-ray diffraction (XRD), nitrogen adsorption-desorption, transmission electron micrographs (TEM), FTIR spectroscopy and thermogravimetric analysis (TGA). With increasing the pH value in the initial mixture, the obtained samples transformed from nanoparticles with intra-particle mesostructures (pH 0.6 and 2.0) to nanoparticles with nonporous structure (pH 3.7), and finally to worm-like porous materials with inter-particle mesostructures (pH 4.2)resulted from the aggregates of nanoparticles. The obtained mesoporous nanoparticles (pH 0.6 and 2.0) have mean diameter of ca. 25 nm, and the pore size distributions are bimodal with fine intra-particle pores and larger inter-particle pores. The intra-particle mesostructure not only retard the growth of nanocrystallites, but also prevent phase transition of anatase to rutile at high temperature. The BET surface area of the TiO2 calcined at 300 C decreased from 212 to 74 m2/g with pH increasing from 0.6 to 4.2.