Precursor concentration-dependent structural, optical and electrical properties of titanium dioxide nanostructures

Titanium dioxide (TiO2) is a widely used material in many industries due to its unique properties, such as high refractive index, high chemical stability, and excellent photocatalytic as well as antimicrobial activity. The anatase phase of TiO2 is particularly important because it exhibits the highest photocatalytic activity among all TiO2 phases. The anatase phase TiO2 nanostructures are synthesized by the Sol-Gel route at a fixed calcination temperature of 600 degrees C and varying precursor concentrations i.e. the number of moles of TTIP and its influence on the structural, optical and electrical properties is investigated. The most prominent peak in XRD spectra is (101) which corresponds to anatase TiO2 with average crystallite size ranging from 20 nm to 37 nm at a TTIP con-centration varying from 6.75 mmol to 16.9 mmol. With the increase of precursor concentration, the dislocation density decreases gradually. The SEM micrograph reveals the formation of nanosheets at lower concentrations and both nanosheets and nanoparticles at higher concentrations. From the UV-visible spectroscopy and four probe resistivity measurements, the energy band gaps and resistivity of the nanostructures are found to decrease with the increase of concentration. For making the theoretical prediction of our experimental results, the DFT was employed to simulate and calculate the structural and electronic properties of the synthesized materials which revealed the indirect band-gap of 1.94 eV for the anatase phase. The XRD spectra generated from the simulated anatase phase also matched the experimental XRD data.