Abstract: Nanoparticles of titanium dioxide doped with nitrogen (N-TiO₂) were synthesized using sol-gel method. Nano-TiO₂ codoped with platinum and nitrogen (Pt/N-TiO₂) was prepared by photolysis-deposition of H2PtCl6 on N-TiO₂ (0.5% (w) Pt). The onset of the absorption spectrum of Pt/N-TiO₂ has a 20 nm red-shift and a weak absorption in the wavelength region from 400 to 500 nm compared with the spectrum of the non- doped catalyst. The photocurrent of Pt/N-TiO₂ electrode is five times higher than that of TiO₂ electrode. The photodegradation yield of trichloroacetic acid over Pt/N-TiO₂ catalyst is 8% under visible light irradiation for 2 ｈ. Doping nitrogen in TiO₂ reduces the band gap of anatase, which makes N-TiO₂ possess catalytic activity in visible light region. Pt clusters precipitated on nano-TiO₂ may retard the recombination of the photo-exited charge carriers and improve interfacial charge transfer. Pt/N-TiO₂ catalyst benefited from both of the effects.

Key words: Nano-TiO₂, Pt and N codoping, Trichloroacetic acid, Visible light, Photodegradation