One-dimensional nanostructures, such as vertically grown TiO2 nanorods offers advantages of aligned and oriented morphology along with unidirectional charge transport and high active surface area. In the present work, we have used four different approaches to further improve the performance and functionalities of the hydrothermally grown TiO2 nanorods.
In the 1st part, we have investigated the effect of synthesis parameters and substrate orientation on the growth process and resultant morphology of the TiO2 nanorods. We demonstrate a substrate position dependant growth of a dandelion like structure, which shows high surface area that is better suited for surface related applications.
In the 2nd part, we report CeO2 functionalized TiO2 nanorods, where the size and distribution of CeO2 nanoparticles are varied through a systematic variation of the hydrothermal temperature to achieve an effective heterojunction between the two materials. A three times higher photocurrent density along with the lowest charge transfer resistance at the electrode-electrolyte interface is observed for the CeO2-TiO2 (nanoparticle-nanorod) heterojunction than that of bare TiO2 nanorods.
In the 3rd part, Ce doped TiO2 nanorod arrays are prepared by one-step hydrothermal method. A significant influence of Ce doping is observed on the crystallinity and morphology of the TiO2 nanorods. Photoelectrochemical measurements show a negative shift in the flat-band potential as a result of Ce doping, which leads to a lower charge transfer resistance at the electrode-electrolyte interface that is also corroborated by impedance spectroscopy data.
In the 4th part, we demonstrate the effect of 100 MeV Ag ion beam irradiation on the structural and electronic properties of TiO2 nanorods. We observed direct to indirect transition of the bandgap and an n to p-type transition in conductivity of the TiO2 nanorods after 100 MeV Ag ion irradiation. The experimental results are analysed with DFT and thermal spike model based calculations to correlate ion beam effect with structure and property modifications.