Phase transformation of TiO2 nanoparticles by femtosecond laser ablation in aqueous solution and deposited on conductive substrate
Titanium dioxide (TiO2) is a wide bandgap semiconductor that is chemically stable, non-toxic, and economical compared to other semiconductors and has been implemented in a wide range of applications such as photocatalysis, photovoltaics, and memresistors. In this work we studied the femtosecond laser ablation of titanium dioxide powders (P25) dispersed either in water or deposited onto fluoride-doped tin oxide (FTO) substrate. The process was used as a route to induce the phase-transformation of TiO2 nanoparticles which results to be governed by the laser parameters such as ablation time and power. It was observed that upon increase of the ablation time of the TiO2 dispersion in water a bandgap widening occurred, leading to the possibility of bandgap engineering of TiO2 using controlled laser parameter profiles.