Robust SiO2@TiO2 nanocoatings with antireflection and photocatalytic self-cleaning properties by introducing commercial P25 TiO2

Abstract

TiO2-based nanocoatings have been applied in practice application of solar cell devices, windows, optical devices, etc., due to their excellent photocatalytic self-cleaning property. However, due to high refractive index of TiO2, it is still a challenge to balance the transmittance, photocatalytic and robust properties of TiO2-based nanocoatings. In this work, we successfully fabricated SiO2 @TiO2 composite nanocoating with mechanical robustness, antireflection (enhanced transmittance) and photocatalytic self-cleaning properties by introducing commercial Degussa P25-type titania nanoparticles (P25) into the system of small solid silica nanoparticles (SSNs) as a building block and acid-catalyzed silica sol (ACSS) as a crosslinking agent, via a simple dip-coating strategy without any post-treatment. The weight ratios of SSNs to P25 were tuned to realize the balance of optical and photocatalytic properties. The optimized nanocoating exhibits a maximum transmittance of ca. 96.5 % at the wavelength of 552 nm, minimum reflectivity of ca. 1.6 % at the wavelength of ca. 600 nm, good hydrophilicity (14.2° of WCAs), high photocatalytic activity of degrading the pollutants, and high mechanical robustness of 3 H pencil hardness test and 5 A tape adhesion test. This work provides a simple and feasible design idea for low-cost and facile fabrication of robust anti-reflection self-cleaning nanocoating.