Laser-assisted modification of titanium dioxide nanotubes in a tilted mode as surface modification and patterning strategy

Electrochemical anodization is regarded as a facile and easily scalable fabrication method of titania nanotubes (TiO2NTs). However, due to the extended duration of calcination and further modifications, much faster alternatives are highly required. As a response to growing interest in laser modification of nanotube arrays, a comprehensive investigation of pulsed-laser irradiation and its effect onto TiO2NT properties has been carried out. The impact of irradiation onto the surface being placed at different angles in respect to the laser beam was studied and evaluated. The usage of the motorized table enables formation of laser-treated traces over the selected area. SEM and TEM analysis provides insight into morphological changes and shows partial melting of nanotubes surface, which is accompanied by the decrease of internal TiO2 tube diameter just below the melted region. Although structural and optical analysis consisting of Raman, photoluminescence and UV-Vis data indicate that presented method does not result in complete material crystallization, it promotes creation of advantageous localized states within TiO2 bandgap that may play a crucial role in charge separation. Moreover, impressive improvements to the mechanical properties resulting from the laser-modification are presented.