Photocatalytic properties of porous titania grown by oblique angle deposition

High surface area nanorods of titanium dioxide were grown by oblique angle deposition on a transparent substrate to investigate their effectiveness as photocatalytic agents for the destruction of organic contaminants in air and water. Optical transmission measurements were made that allowed for an estimation of the porosity of the film (75%-78%). Comparing transmission measurements with those from a dense anatase film showed that the penetration depth for the light into the nanorod film was 2.5 times that in a dense, anatase film. The photocatalytic degradation of indigo carmine dye on the porous films was shown to depend on film thickness and annealing conditions. The effectiveness of the film was assessed by observing the change in absorbance of the dye at 610 nm over time and quantifying the film performance using a pseudo-first-order reaction rate model. Reaction rates increased as the film thickness increased from 600 nm to 1000 nm, but leveled out or decreased at thicknesses beyond 1500 nm. A transp...