Highly Active Crystalline Mesoporous TiO2 Films Coated onto Polycarbonate Substrates for Self-Cleaning Applications

SiO2 film precoating is found to be very effective for the protection of polycarbonate (PC) as a typical example for heat-sensitive substrate materials, thus preventing its photodegradation under UV light. Subsequently, transparent photoactive mesoporous TiO2 and Sachtleben Hombikat UV100 thin film coatings on SiO2/PC have been developed for self-cleaning applications. The newly prepared photocatalysts films have been compared with either a film prepared from a commercial photocatalyst (Sachtleben Hombikat UV-100), SG-TiO2, or Pilkington Glass Activ (TM) by the determination of their photonic efficiencies for degradation of methylene blue and the photoinduced surface wettability. The efficiency of the photocatalytic reactions was found to be about three times higher in the case of the mesoporous TiO2 films compared with films prepared from UV-100 or Pilkington Glass Activ (TM). This is the first report focusing on the synthesis of mesoporous TiO2 films on polycarbonate substrates, and, to the best of our knowledge, the measured photonic efficiency of zeta = 0.078% for these meso-TiO2 films on PC is among the highest zeta-values reported up to now even when using soda-lime glass substrates.