Growth of titanium dioxide thin layers by low pressure chemical vapor deposition (LPCVD) and chemical vapor infiltration (CVI) for photocatalytic uses

We present preliminary results of a work aiming the growth of titanium dioxide thin layers by Low-Pressure Chemical Vapour Deposition (LPCVD) and by Chemical Vapour Infiltration (CVI). These TiO2 coatings are grown on glass plates (LPCVD) and on porous substrates made of micro-fibres (13 - 17 μm in diameter) of fused silica (CVI). The precursor used as organometallic source was Ti(OiPr)4. As-grown films were morphologically, optically and structurally characterized, and then submitted to photocatalytic tests using aqueous orange G solutions. The films grown on glass plates show a columnar growth mode. These films exhibit a good crystallinity and are constituted of anatase orientated (211) and (101) depending of their position in the reactor. The films grown on fused silica micro-fibres show a good surface coverage and exhibit a micro-porous structure due to the high surface curvature of the substrates. The photocatalytic activity was investigated for two TiO2 films with different thicknesses (70 and 200 nm) grown on porous samples.