Modification of nanosized anatase titanium dioxide by microwave irradiation

Abstract

Nanosized particles of anatase titanium oxide (TiO₂) were synthesised by hydrolysis of a titanium ester (Ti(OC₄H₉)₄) in basic media followed by dehydration in acid media. Mixtures of the anatase nanopowders, hydrazine (NH₂=NH₂) and carbon black were subjected to microwave treatment. The effect of microwave reaction conditions on the photocatalytic activity of the resulting powders in promoting reduction of Cr₂O₇^2– was investigated. The modified powders were characterised by X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible spectrophotometer. A peak at 399˙6 eV in the N 1s X-ray photoelectron spectroscopy spectra obtained following microwave treatment indicated that nitrogen doped titanium oxide (TiO_2–xN_x) was obtained. The ultraviolet-visible spectra indicated that the light absorption edge of TiO_2–xN_x obtained by microwave treatment of TiO₂ had moved to the visible region. The X-ray diffraction data indicated that the crystallographic structure and particles dimensions were apparently unaffected by microwave treatment. The powder mixture irradiated for 20 min exhibited the best photocatalytic activity.

Keywords:

• TITANIUM DIOXIDE
• PHOTOCATALYTIC ACTIVITY
• SURFACE MODIFICATION
• MICROWAVE IRRADIATION
• NITRIFICATION