Synthesis of Raspberry-Like SiO₂–TiO₂ Nanoparticles toward Antireflective and Self-Cleaning Coatings

Abstract

Silica-titania core-shell nanoparticles of 30, 40, 50, 55, 75, and 110 nm were prepared from tetraethyl orthosilicate (TEOS) and tetraisopropyl titanate (TIPT). After calcination, the amorphous titania shell transformed into anatase nanoparticles, and the silica-titania core-shell nanoparticles became raspberry-like nanoparticles. These nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and UV-vis spectroscopy. Hierarchically structured antireflective and self-cleaning particulate coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly using silica-titania core-shell nanoparticles and silica nanoparticles as building blocks followed by calcination. The maximum transmittance of coated glass substrates reached as high as ca. 97%, while that of the glass substrates is only ca. 91%. The morphologies of the coatings were observed by SEM and atom force microscopy (AFM). Such hierarchically structured raspberry-like SiO2-TiO2 nanoparticle coatings had superhydrophilic and antifogging properties. The coatings also showed photocatalytic activity toward organic pollutants and thus a self-cleaning property.

Recent Progress in Self-Cleaning Materials with Different Suitable Applications

“…Two characteristics of surface structural morphology and also physiochemical properties of titanium materials play a significant duty in anti-bacterial activity (Mokhtarimehr et al, 2015). The structure of AgI/TiO 2 has shown potential as it has efficient photocatalytic activity with regards to antibacterial cases and organic pollutants (Wang et al, 2014a;Li and He, 2013). The active visible light self-cleaning of cotton fibers coated with AgI and TiO 2 shows a more efficient degradation of methyl orange after visible light irradiation, as compared to the self-cleaning activity of cotton fibres coated with TiO 2 alone (Nakata et al, 2014).…”

Superlyophilic Interfaces and Their Applications

“…[101,102] However the dispersion of particles has been an obstacle when it comes to applications, such as catalysis, supercapacitors, drug delivery, etc. [103,104] To solve the problem of low dispersibility, rendering the interface of particles to SLPL is an ideal solution.…”

Chances and limitations of nanosized titanium dioxide practical application in view of its physicochemical properties

“…The interest in nano-TiO2 started with the discovery of its catalytic properties induced by UV radiation, in the beginning of the 1970s of the twentieth century [65] -and it is still growing [12, 66,67]. There is already a lot of literature data presenting the mechanism of the conversion of solar energy into chemical energy and on the possibilities of increasing the photocatalysis efficiency, both homogeneous (e.g.…”

“…It allows to obtain a thin, homogeneous, quickly evaporating, invisible and pollutant-removing film of water [83]. That is why glass surfaces covered by a thin layer of nano-TiO2 are applied in manufacturing of fog-free mirrors [84] or self-cleaning windows [ 66]. It is not the only example of the practical application of the nanoTiO2 strong hydrophilicity.…”

“…To summarize, surfaces covered by photocatalytic coatings that contain nanosized metal oxides, i.e. nano-TiO2, exhibit -when irradiated by UV -not only antistatic [33] or deodorizing [20] properties but, more importantly, they also have self-disinfecting [88,89] and self-cleaning abilities [13,66].…”