Sol-gel based TiO₂ thin film deposition on frustules towards facile and scalable manufacturing

Diatom frustules have drawn a lot of attention from engineering researchers in the past decades. As a type of biomaterial, diatom frustules have been applied in a variety of areas such as biosensors and solar cells due to their excellent material and optical properties. Titanium dioxide (TiO₂), on the other hand, is also semiconductor material and photocatalyst, micro and nanoparticles of which can be found in applications such as dye sensitised solar cells (DSSC). It has been demonstrated that by using diatom frustule-TiO₂ composite particles in DSSCs, the performance of the solar cells could be increased. In this paper, we introduce a sol- gel based method to deposit TiO₂ layers on the surface of diatom frustules. TiO₂ nanoparticles were deposited on the surface of the frustules. After a subsequent annealing process, TiO₂ crystal grains were formed. The method in this paper has the potential for scalable manufacturing of frustule-TiO₂ composite materials for future solar cell applications.