Effect of hydrothermal reaction time and etching on nanorod TiO₂ thin film

Titanium dioxide (TiO₂) has the most potential function in numerous research domains because of its various advantages. Among the variety of ways, TiO₂ nanorods (TNRs) are one of interest nanoparticle structures due to their superior delocalisation of the electron holes pair and lower charge recombination. However, TNRs inhibit solar spectrum absorption and have a high resistivity. In this study, etching treatment is introduced to increase the specific surface area and reduce resistivity. The effect of reaction time was investigated on TNRs thin film by using the hydrothermal method. From the findings, the 8-hour reaction time of TNRs thin film revealed the most striking characteristics. The preferred (101)-orientation of TNRs was observed and the diameter of rods increased along with reaction time. As the reaction time rises, the bandgap energy of TNRs approaches the value of 3.0 eV and presents a compact surface. After etching treatment, the peak intensity of (101)-orientation of TNRs increases indicating high crystallinity. The morphology of nanorods changed into smaller rods, apparently a nanowire with deeper depth. The surface roughness and band gap increased due to the surface area affected by etching. The electrical properties of etched-TNRs thin film after showed a reduction of resistivity aligning to thickness decrement. Thus, hydrothermal etching treatment showed effectiveness in enhancing TNRs properties in terms of crystallinity, surface morphology and reducing resistivity.