Fabrication and characterization of a porous titanium dioxide film with sub-micropores

• Ion bombarding can be used to make sub-micropores on the TiO2 film by sol–gel method.
• The formation mechanism of those pores should be spike sputtering, expanding the active surface.
• The photocatalytic effect of the porous film is distinctly better than that of the conventional film.

A porous anatase TiO2 (titanium dioxide) film with sub-micropores, which displays a good photocatalysis, was successfully fabricated using a multiple technique of sol–gel and ion bombarding, and the formation mechanism is analyzed for these pores. Firstly a clean substrate was coated with a sol of the precursor of titanium dioxide and subsequently sintered to yield a dense TiO2 film, then bombarded by the metal ion to form a porous film with a number of sub-micropores. These pores effectively expand the available active room of the film for liquid mediums and the results are of considerable significance to potential applications of the titanium dioxide film for catalysis. The experimental results of the photocatalytic decomposition of a methyl orange solution show that the photocatalytic effect of this dense film under ultraviolet light is distinctly better than that of the dense TiO2 film prepared by the conventional sol–gel method. Linearly fitting the curves of relation between the absorbance of methyl orange solution and the time of photocatalysis indicates that the catalytic reaction velocity constants are closely 4.8 × 10−3 min−1 for the porous film and 1.2 × 10−3 min−1 for the dense film under ultraviolet light, respectively.