Titanium dioxide nanoparticles, is another good nanoparticle other than the carbon. Titanium Dioxide (TiO 2 ) Titanium dioxide powder exists in both bulk and nanoform, as well as in various crystalline modifications including rutile and anatase. In its bulk form, it has been used extensively as white pigment showing maximum reflectivity at a particle size of ∼300nm. Titanium dioxide is also an effective UV filter.
The nanoform (∼50nm)is transparent, which provides an esthetic advantage for uses in sunscreens (mostly rutile). Nanoform TiO 2 in the anatase modificatio also has specific electrical and photo-catalytic as well as antimicrobial properties. The nanoform of anatase is reported to be more reactive than the bulk form. There are various methods available for the production of small nTiO 2 but the sol–gel method has been widely used since it is deemed relatively inexpensive.
Unfortunately, titanium dioxide nanoparticles…!
Unfortunately, the sol–gel derived material is amorphous in nature and often requires a further treatment to induce crystallization. Elevated treatment temperatures (higher than 350 ∘ C) are often necessary to expedite the transition from the amorphous material to the crystalline anatase phase, but such high temperatures result in increased size of the nanoparticles and subsequently a decrease in the surface area. Apart from sunscreens, the UV filtering property of TiO 2 is also used in coatings for plastics and metals, varnishes for wood preservation, in textile fibers and in packaging films Another main use is catalysts (e.g., decomposing NOx into nitrates or N 2 ).
The photo-catalytic and antimicrobial properties are used in “self-cleaning” products (e.g., windows, cement, tiles, and textiles for use in hospitals) and air purification systems. Use of tribological coatings prevents deposits in engines and enhances fuel efficiently. TiO 2 nanoparticles are also used to increase scratch resistance of coatings and in the production of electronic components and dental impressions. TiO 2 can also be used in dye-sensitized solar cells to produce electricity, although efficiently is currently lower than traditional silicon solar cells.