Titanium dioxide (TiO2) is an inorganic compound usually extracted from a titanium-iron mineral, ilmenite, and sometimes from rutile. To create pure titanium dioxide the compounds are chemically separated. It is found as a solid due to its high melting point 1843°C and is insoluble in water. It was first discovered in 1791 and has become the most used white pigment in the world.
Used extensively in paints, coatings, plastics, paper, inks, fibres, foods, and cosmetics. Stable, non-flammable and non-toxic, TiO2 has replaced antiquated lead compounds, due to its superior qualities. Its excellent reflectively results in a brilliant-white colour and its resistance to light, heat and moisture prevents it from degrading.
Titanium dioxide’s high-refractive index has led to its popularity as a UV-blocker in sunscreen. TiO2-containing sunscreens offer broad spectrum UV protection against both UVB and UVA2 which includes wavelengths from 315–340 nm, also called, short waves. Through its adoption in skincare, TiO2 has contributed to the prevention of skin cancer and skin aging, and the micro-particles are considered safe to use at approved concentrations in sunscreens.
TiO2 has been utilised in various sustainable products. In warm areas of the world it is used in thermal reflective paint, on buildings, to divert light and heat, thereby reducing the dependence on air conditioning. Additionally, due to its high opacity, paints that contain the pigment can be applied in thinner, or singular coats; reducing the overall amount of material used.
Low-cost, thin-film dye-sensitized solar cells (DSSCs) use a TiO2-dye for an anode and a platinum cathode, separated by an electrolytic solution. Sunlight passes through the transparent electrode, allowing it to reach the anode where it excites the TiO2 nanoparticles, a current is induced. DSSCs benefit from reduced cost of manufacture, and traditional printing methods can be used to apply the dyes.
As well as being used in solar cells, Titanium Dioxide nanoparticles can be used in automotive catalytic converters in order to remove harmful NOx emissions, further cementing the material’s potential for a green future.
Due to its abundance TiO2, has been studied for its potential use in other areas. There have been recent advances using titanium dioxide in cancer therapy, drug delivery systems and cell imaging. Research at The University of Hampshire has showed the anti-cancerous effect of TiO2 in animal cells indicating that photoexcited TiO2 nanoparticles may be a potential way to treat cancer in the future. These nanocomposites were shown to increase the accumulation of doxorubicin (a chemotherapy drug) in tumour cells, resulting in the enhanced death of mutated cells. This was also complemented by a reduction in he toxic side effects of doxorubicin.