Photocatalytic effect of thermal atomic layer deposition of TiO2 on stainless steel

The thermal atomic layer deposition (Th-ALD) of TiO2 films on stainless steel for use as a photocatalyst was investigated and compared to plasma-enhanced ALD (PE-ALD) using the same precursor. Th-ALD TiO2 films were deposited on stainless steel using a Ti(NMe2)4 [tetrakis(dimethylamido) Ti, TDMAT] precursor. The microstructure of the Th-ALD TiO2 films was greatly dependent on the growth temperature as an amorphous structure was obtained at 200 °C and a polycrystalline structure was achieved at temperatures above 300 °C. From the contact angle measurement of water, the crystalline TiO2 films exhibited super-hydrophilicity after UV irradiation. The anatase phase of both the Th- and PE-ALD TiO2 films grown on stainless steel showed higher photocatalytic abilities than the rutile phase grown at 400 °C. In addition, the anatase PE-ALD TiO2 film demonstrated a higher photocatalytic efficiency than the Th-ALD films. The photocatalytic efficiency of the Th-ALD TiO2 films was investigated as a function of film thickness and it was found that the efficiency was saturated above a film thickness of 120 nm.

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► Preparation of thermal-ALD TiO2 films as a photocatalyst.
► Comparative study of chemical and photocatalyst ability on thermal-ALD and plasma enhanced ALD TiO2 films as a photocatalyst.
► Investigation of the difference and advantage of each ALD process.