Nanostructured glass coatings for solar control with photocatalytic properties

Sol–gel derived solar control coatings have been deposited by sol–gel on soda-lime substrates, in the form of Bragg mirrors consisting of alternating aluminosilicate glass and titania quarter-wavelength thick multilayer stacks. These were first modelled by the Transfer Matrix Method and then deposited by spin-coating, with the aim of acting both as near ultra-violet (NUV) and near infrared (NIR) reflecting coatings. Optical spectroscopy measurements from the NUV to the NIR have shown that these multilayer coatings possess solar control properties, namely exhibiting reflection peaks in the NUV (centred at ~ 350–400 nm) and in the NIR (at ~ 1000 nm) with a reflectivity of up to ~ 90%, while preserving the visible range transmission. Grazing incidence X-ray diffraction analysis has identified the presence of titania in anatase phase with an estimated size around ~ 20 nm.Photocatalytic functionality was also added to the solar control coatings through the subsequent deposition of a mesoporous anatase TiO2 film, prepared via sol–gel using the evaporation-induced self-assembly technique. The photocatalytic activity was evaluated through the oxidation of methyl orange (MO) dye in aqueous solution, under UV irradiation. Visible spectroscopy measurements have shown that these mesoporous TiO2 coatings promoted the photocatalytic degradation of MO, reaching a maximum value of ~ 40%. Transmission electron microscopy analysis confirms the presence of a porous structure.

► Coupling solar control and photocatalytic functionalities on the same glass coating
► Transfer Matrix Method simulations of Bragg mirrors multilayer structures
► Reflection peaks in NUV and NIR, and transmission of ~ 70–80% in the visible range