Enhanced photocatalytic activity of hierarchically micro-/nano-porous TiO2 films

Photocatalytic activity of hierarchically micro-/nano-porous film is studied for the first time. The results show its catalytic activity was increased ca. 30–40% and ca. 60–70% for mineralizing gaseous acetaldehyde and liquid-phase phenol, respectively, comparing to that of nano-structured film. Hierarchical TiO2 porous film produces continuously composite pore channels, providing the fast transport pathway for reactants, products and O2 moving into and out of the catalytic framework. Additionally, due to extended optical path length from light scattering effect in composite film, the light-absorption efficiency is enhanced distinctly in the range of 380–410 nm, which is close to P25 TiO2 band-gap edge. The presented investigation indicates that the pores structure plays important roles in the photocatalytic characters of films photocatalyst. More important, the as-prepared film catalyst gives a promising future for its actual application.