A new material has been developed by embedding graphene, in roll-up form, in titanium-dioxide composite nanofibre. It is used as a photocatalyst to harvest light, in order to generate electrons and positive holes. These electrons are transferred to various sites along the nanofiber where reactions are needed, and reacts with oxygen in air to generate super-anions, while the remaining positive holes react with water vapour in air to generate hydroxyl radicals. The highly conductive nature of graphene allows ample flow of electrons and hydroxyl radicals, and these promote the oxidation of pollutant gas molecules and bacteria/viruses that are adsorbed onto the nanofibres. The semiconductor nanofibre is made up of nano-crystals, and the embedded graphene is exposed in the pores between these nano-crystals. Graphene increases the surface area, by 44% to 80 m2/g, for adsorption of harmful gaseous molecules and harvesting of light, that covers both ultraviolet and visible spectrum.
The composite of TiO2-ZnO-Bi2O3 (TZB) with graphene, enables the conversion of NO to NO2 at a conversion efficiency of 70%. Under similar conditions, the conversion efficiency of 25-nm TiO2 nanoparticles is only 9.6%. The new material’s conversion efficiency is 7 times that of traditional TiO2, and it is 60% better than TZB without graphene. It can harvest more light and transport these charges more efficiently than conventional TiO2 nanoparticles, avoiding electron-hole recombination.
This technology, with addition of a nanofiber particulate filter upstream, allows the general public to benefit from inhaling clean air that is free from particulates and harmful gases.
This technology features graphene embedded in semiconductor nanofibre of 80 nm in diameter, which is a new invention that combines both semiconductor and high charge conductivity properties. There are three key advantages:
This technology can be applied (but not limited to) in the following areas:
When used as a photocatalyst, users can breathe fresh air that is free from harmful gases. This reduces the chance of getting respiratory problems, cardiovascular diseases, and lung cancer. When used for disinfection, viruses (such as common cold/influenza, H3N4, SARS, MERS) and bacteria can be eliminated.