Nanocomposites and nanomaterials

Photocatalytic activity of C, N, F-doped TiO2 nanostructures in doxycycline degradation
Romanovska N.I., Manoryk P.A., Grebennikov V.M, 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

Nonmetal doped and codoped TiO2 nanomaterials are widely investigated as photocatalysts, wide gap semiconductors for solar cells, hydrophobic coatings etc. Usually, F-doped TiO2 obtained by simple hydrothermal method with hydrofluoric acid. As result, F-ions inhibit crystal growth and induce {001} facets formation, but HF is extremely corrosive and toxicity. Nowadays, other fluoride compounds are actively investigated for synthesis of F-doped TiO2 nanostructure.
The aim of this work was the investigation of NH4F/Ti(Buo)4=R ratios in the reaction mixtures influence on the phase composition, morphology, texture and photocatalytic activity of the samples obtained in the degradation of doxycycline (DC) under UV- and visible light irradiation.
It was shown, that solvothermal sol-gel method, together with variation of NH4F/Ti(Buo)4 in reaction mixture, provides C, N, F-TiO2 nanostructures formation. The phase composition of obtained TiO2 strongly depends on NH4F/Ti(Buo)4 in the reaction mixture. At R from 0 to 0.07 anatase-brookite phase was formed, and after increasing R from 0.14 to 0.27 the anatase phase formed only, that it can be concluded that NH4F inhibit the formation of the brookite phase. The crystallite size of samples after solvothermal treatment increase from 8 to 20 nm with R elevating and increase after calcination. The presence of F-ions in reaction mixture induces sheet-like structure formation and its morphology transforming into spheroidal during calcinating. These samples have interstitial nitrogen and carbon and surface Ti-F groups. Photocatalytic activity of C, N, F-TiO2 was investigated in DC degradation under UV and visible light irradiation. It was shown that the conversion degree of DC during 60 min under visible light irradiation was more than 1.5 higher than P-25.
As result, C, N, F-TiO2 nanostructure was synthesized by the solvothermal sol-gel method, using NH4F as fluorine source. It was shown, that phase composition, texture and morphology strongly depends on R. These materials demonstrate visible light photocatalytic activity in doxycycline photodegradation.