Aerosol processing of hierarchically organized TiO2 based nano-particles

Abstract

The low-temperature (T=150oC) aerosol route, representing a feasible bottom-up technique for nano materials processing in disperse system, was applied for the synthesis of spherical, non-agglomerated, hierarchically organized titanium dioxide (TiO2) nano-particles. The diverse levels of structural, morphological and functional complexity were explored simply by means of appropriate selection of different colloidal precursor solutions of either nearly spherical nano-particles[1] (a), surface modified nano-particles with dopamine (b) or nano-tubes (c). The detailed structural and morphological investigations were done by X-ray powder diffraction (XRPD), laser particle size (LPS) analysis, scanning and field emission electron microscopy (SEM/FESEM) and transmission electron microscopy (TEM). Spherical, submicronic, soft and grained TiO2 particles with the mean size from ~350 to ~450nm and with clustered inner structure, composed of primary nanocrystals (<10nm), were obtained. The optical properties and surface structure were analyzed by UV-Vis diffusive reflectance (UV-Vis DRS) and Fourier transform infrared (FTIR) spectroscopy. The obtained results offer a general route for the synthesis of self-assemblies with tunable morphology and optical properties. A significant decrease of the effective band gap values (1.7 to 1.9eV) for the processed TiO2 nanoparticles, compared to the band gap of bulk material (3.2eV), was achieved. Such hierarchical nano-structured powders, are expected to have potential application not only in the field of photovoltaic technologies[3] but also in various aspects of photo catalysis.[4]References:[1] Dugandžić I.M., Jovanović D.J., Mančić L.T., Zheng N., Ahrenkiel S.P., Milošević O.B., Šaponjić Z.V. and Nedeljković J.M., 2012 Surface modification of submicronic TiO2 particles prepared by ultrasonic spray pyrolysis for visible light absorption, J. Nanopart. Res., 14 (10) 1157 (DOI10.1007/s11051-012-1157-1)[3] Zhang Q., Myers D., Lan J., Jenekhe S.A. and Cao G., 2012 Applications of light scattering in dyesensitized solar cells, Phys. Chem. Chem. Phys., 14, 14982-14998[4] Liu B., Nakata K., Sakai M., Saito H., Ochiai T., Murakami T., Takagi K. and Fujishima A., 2012 Hierarchical TiO2 spherical nanostructures with tunable pore size, pore volume and specific surface area: facile preparation and high-photocatalytic performance Catal. Sci. Technol., 2, 1933-1939