Atomic layer deposited (ALD) TiO₂ and TiO_2−x-N_x thin film photocatalysts in salicylic acid decomposition

Degradation of salicylic acid (SA) with thin film photocatalyst, titanium dioxide (TiO₂) and nitrogen-doped TiO₂ (TiO_2−x-N_x) combined with ultraviolet (UV) radiation was studied. TiO₂ film with thickness of 15 and 65 nm was tested. The TiO_2−x-N_x film had thickness of 15 nm on top of TiO₂ (50 nm). Photocatalysts were prepared on glass substrate by atomic layer deposition (ALD) technique. The effect of initial pH (3–10) was studied with SA concentration of 10 mg/l. Decomposition of SA was fastest at pH 6 with both films and the rate was equal at initial pH values 3 and 4.3. However, at higher pH values the non-doped film was more efficient.