Amorphous titanium dioxide precursor material, method of producing thereof and method of controlling crystalline phases thereof

A method of converting amorphous titanium dioxide nanoparticles into crystalline titanium dioxide nanoparticles, the method comprising:

• synthesizing a precursor comprising amorphous undoped titanium dioxide (TiO2) nanoparticles via an incomplete non-hydrolytic sol-gel ester elimination reaction using titanium (IV) isopropoxide and oleic acid such that oxygen vacancies creating band states within a TiO2 band gap are generated within the amorphous undoped TiO2 nanoparticles;
• depositing the precursor onto a substrate to form a film of amorphous undoped TiO2 nanoparticles;
• and
• selectively exposing one or more regions of the film to an irradiation source having an energy lower than a band gap of TiO2 such that the amorphous undoped TiO2 nanoparticles within each of said one or more regions are independently converted to one of an anatase TiO2 phase, a mixed anatase-rutile TiO2 phase and a rutile TiO2 phase, thereby yielding said crystalline titanium dioxide nanoparticles,
• wherein
• the band states within the TiO2 band gap are such that exposure to the irradiation source triggers an initial conversion of the amorphous undoped TiO2 nanoparticles within said one or more regions to said anatase TiO2 phase;
• and increased exposure of said anatase TiO2 phase to the irradiation source results initially in a conversion of said anatase TiO2 phase to said mixed anatase-rutile TiO2 phase, and subsequently to said rutile TiO2 phase.