Abstract: The immobilized photocatalyst, TiO₂ film supported on activated carbon fibers (TiO₂/ACFs) prepared with molecular adsorption-deposition (MAD), exhibits high stability in cyclic photodegradation runs. The interposition fixing structure between TiO₂ film and carbon fiber was investigated by means of SEM-EDX, XRD, XPS and FTIR, and a model was proposed to explain this structure. With SEM examination of carbon fiber surface after removing the deposited TiO₂ film, a residual TiO₂ super-thin film was found to exist still. By determining surface groups on ACFs, titanium sulfate (Ti₂(SO₄)₃) in burnt remainders of the TiO₂/ACFs was thought to be formed with an interfacial reaction between TiO₂ film and carbon fibers. These provide some evidence of firm attachment of TiO₂ film to carbon fiber surface. In the consideration of characteristics of the MAD, the deposition mechanism of TiO₂ film on ACFs was proposed, and the interposition fixing structure was inferred to intercrossedly form between TiO₂ film and ACFs’ surface. This structure leaded to firm attachment and high stability of the TiO₂ film.

Key words: TiO₂ film; activated carbon fibers; interposition fixing structure; stability