Self-Cleaning Spray Deposited Thin Films Based on TiO2 and WO3 for Glazings

Individual TiO
₂
and WO
₃
, as well as stacked TiO
₂
/WO
₃
thin films with self-cleaning properties were sprayed onto a solar glass substrate. The composite thin film exhibits superhydrophilicity (water contact angle 10.2°) due to the use of WO
₃
as outer layer. In spite of its high carbon content, which delays its photocatalytic activation, it exhibited higher efficiency in the methylene blue removal than the individual TiO
₂
or WO
₃
layers after 6 h of irradiation (solar simulated radiation at low irradiance, G=34 W/m
²
). The high VIS-transmittance (>80%) recommends the films for self-cleaning coatings on glazing and on other transparent substrates.