Nanocomposites and nanomaterials

Preparation, characterization of C-doped TiO2 nanostructures and their photocatalytic activity in visible-light induced decomposition of hydrazine
Romanovska N.I., Manoryk P.A., Shulzhenko O.V.
Physico-inorganic chemistry Department, L.V. Pysarzhevskii Institute of Physical Chemistry of the NAS of Ukraine. Prospect Nauki, 31, Kyiv-03039, Ukraine. 
E-mail: nat.romanovska@gmail.com

TiO2 nanostructures are widely investigated as photocatalytic materials in ecological photocatalysis, conductive films for solar cells and Li-ion batteries etc. But, TiO2 can photogenerate e-/h+ pairs only under UV-light irradiation, whose share is only 4-5% of solar radiation. That why, nonmetal doping of TiO2 was investigated as one of an effective instruments for the band gap narrowing and sensitization in the visible-light region. Carbon containing compounds are widely used as carbon precursors in C-doped TiO2 synthesis, but influence of C-doping on phase composition, morphology, texture were investigated not enough. 
The aim of this work was the investigation of phase composition, crystallites size, morphology, texture characteristics of C-TiO2, obtained by hydrothermal sol-gel method, and testing of their photocatalytic activity in hydrazine photodecomposition  processes. The C-TiO2 were characterized by XRD, SEM, TEM, N2-ad/desorption, UV-Vis and FTIR-spectroscopy.
It was shown, that carboxylic acids induce anatase phase formation with crystallites size near to 10 nm. The particles size and shape of C-TiO2 doesn’t change significantly with carbon content increasing. The texture characteristics are extremely dependent on dopant content and the maximal SBET and dmeso were 205 m2/g and 5.5 nm respectively. The C-TiO2 nanostructures characterized by band gap narrowing to 3,0 eV and wide adsorption band in the visible light range of UV-Vis spectra. The photocatalytic activity of C-TiO2 was investigated in photocatalytic degradation of hydrazine under UV- and visible light irradiation. The conversion degree of hydrazine on C-TiO2 is practically independent on dopant amount under UV-light irradiation, but extremely changes under visible light irradiation. The high conversion degree of hydrazine on C-TiO2 may be induced by synergetic effect of carbon doping and high surface area with small mesopore diameter. It could be concluded, that C-TiO2 nanostructures obtained by hydrothermal sol-gel method have a small anatase crystallites size, are characterized by high surface area values and demonstrate photocatalytic activity in hydrazine decomposition process under visible light irradiation.