Synthesis of Visible Light-Active Nanostructured TiO₂ via Femtosecond Laser Irradiation in Air

ABSTRACT

In this study, we report formation of weblike fibrous nanostructure and nanoparticles with Ti-oxide nanospheres due to irradiation of bulk titanium samples with femtosecond laser radiation at megahertz pulse repetition frequency in air at atmospheric pressure. The formation of a fibrous nanostructure layer on the treated surface leads to a significant decrease in the reflection of visible radiation. For the visible wavelength, the decreased reflection is a result of the nature of the nanostructure. Scanning electron microscopy analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanoparticle diameter varies between 30 and 90 nm and the nanoparticles are mixed with nanospheres of a few nanometers in diameter. Micro-Raman analysis revealed metallic and oxide phases in the nanostructure. X-ray diffraction confirmed the formation of rutile TiO₂. The growth of TiO₂ nanostructure is highly recommended for the applications of dye-sensitized solar cells and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline TiO₂ films for photovoltaic applications.

KEYWORDS:

• laser
• nanofibers
• nanopartcles
• solar