Synthesis of Visible‐Light‐Activated Yellow Amorphous TiO₂ Photocatalyst

Abstract

Visible‐light‐activated yellow amorphous TiO 2 (yam‐TiO 2 ) was synthesised by a simple and organic‐free precipitation method. TiN, an alternative precursor for TiO 2 preparation, was dissolved in hydrogen peroxide under acidic condition (pH ~ 1) adjusted by nitric acid. The yellow precipitate was obtained after adjusting pH of the resultant red brown solution to 2 with NH 4 OH. The BET surface area of this sample was 261 m 2 /g. The visible light photoactivity was evaluated on the basis of the photobleaching of methylene blue (MB) in an aqueous solution by using a 250 W metal halide bulb equipped with UV cutoff filter ( λ > 420 nm) under aerobic conditions. Yam‐TiO 2 exhibits an interesting property of being both surface adsorbent and photoactive under visible light. It was assigned to the η 2 ‐peroxide, an active intermediate form of the addition of H 2 O 2 into crystallined TiO 2 photocatalyst. It can be concluded that an active intermediate form of titanium peroxo species in photocatalytic process can be synthesised and used as a visible‐light‐driven photocatalyst.