Enhancing photocatalytic ability of TiO₂ films using gel-derived P/Si-TiO₂ powder

P/Si-TiO₂ photocatalytic thick films on FTO glass substrates were prepared. TiO₂ thin films, as base layer, were first coated on substrates using a spin-coating technique. The slurry containing P/Si-TiO₂ nanoparticles was bar-coated on the surface of TiO₂ base layer, followed by calcining at 550 °C. The resultant films were characterized using x-ray diffractometer, scanning electron microscope, UV–Vis spectrophotometer, crosscut adhesion test, and recycling-use test. Under 365-nm UV-light irradiation, abilities of the films to photocatalytically degrade methylene blue were evaluated. The apparent rate laws obeyed 1st-order and the corresponding reaction rate constants (k′), based on the coated area of substrates, were estimated. k′ of the thick film (thickness: 6.5 μm; composition: P/Si-TiO₂ anatase crystallites with 16 nm average size) was 49.0 L/(m²-sub. h), which was about eight times of that of the thin film (k′ = 6.2 L/(m²-sub. h); thickness: 215 nm; composition: pure TiO₂ anatase crystallites with 8-nm average size).