Photovoltaic enhancement of nanostructured boron-doped rutile phase TiO2 nanorods via facile hydrothermal method

Several doping processes are being investigated for the enhancement and efficient utilization of TiO2 properties with increased focus on the crystallinity and mobility of TiO2 nanorods. In this study, boron (B) was chosen as the dopant for its small orbital states of B3+ when compared to Ti4+. The B-doped TiO2 nanorods were fabricated on pre-cleaned fluorine-doped tin oxide substrate using hydrothermal method. The structural characterization was done by X-ray diffraction spectroscopy with diffraction angle fixed at 0.5° which was further confirmed by Raman spectroscopy. X-ray photoelectron spectroscopy was employed to analyse the elemental composition of the samples while the morphological characterization was achieved with the use of field-emission scanning electron microscopy and transmission electron microscopy. The absorption spectra were obtained using UV–Visible spectroscopy and the bandgap calculated from Tauc’s plot. The photocurrent properties were analysed by photoelectrochemical-based self-powered photodetector. No significant changes were observed in the morphology of the TiO2 nanorods after doping. Both the crystallinity and mobility of TiO2 nanorods from the B atom were increased. X-ray photoelectron and UV–Vis spectroscopy both confirmed that B dopant was present in interstitial and substitutional positions in the TiO2 lattice even in low B dopant concentration. The photocurrent analysis indicates increased output current from 5.0 µA of pristine nanorods, to 16.5 µA of 1.00 wt% B-doped rutile TiO2 nanorods, implying their enhanced electron transport. This was also proven by electrochemical impedance spectroscopy analysis where 1.00 wt% of B-doped TiO2 showed the lowest electron recombination rate at electrolyte/working electrode interface. The results of this study can be used to improve the activities of solar cells, UV photodetector, or for photocatalytic applications.