Synthesis and Characterization of Doped TiO2 Nanoparticles for Bandgap Engineering

Abstract

In this project, modified sol-gel method was used for the synthesis of doped and co-doped TiO2 nanoparticles (NPs) at room temperature. Two sets of doped TiO2 nanoparticles were synthesized in order to fine tune the bandgap and to carry out comparative study of the direct and indirect bandgap of all prepared samples. First set of TiO2 samples consisted of (1, 3 and 5 mol %) Ce doped TiO2, (1, 3 and 5 mol %) F doped TiO2, (1, 3 and 5 mol % ) Mn doped TiO2 alongwith pure TiO2 whereas the second set consisted of (1,3 and 5 mol % ) CeF co-doped TiO2 and (1, 3 and 5 mol % ) MnF co-doped TiO2, where both co-dopants were added in the same mol % .The goal of this project was to carry out room temperature synthesis of doped and co-doped TiO2 without using any surfactant or capping agent and to investigate whether direct bandgap is larger than indirect bandgap for doped TiO2 or this trend is only limited to pure TiO2.The synthesized samples were analyzed by using UV-Vis DRS, FTIR, XRD and SEM. UV-Vis DRS analysis confirmed the bandgap narrowing of TiO2 nanoparticles due to doping and co-doping. Modified Kubelka-Munk Function was used for direct bandgap and indirect bandgap calculations. The obtained Tauc plots confirmed that the trend was followed appropriately by all doped and co-doped samples with no anomaly. XRD analysis confirmed that doping as well as co-doping of TiO2 nanoparticles was done successfully. SEM analysis confirmed the spherical morphology of synthesized TiO2 nanoparticles. It was also confirmed that TiO2 nanoparticles morphology was not much affected by doping as well as co-doping yet the incorporation of dopants in TiO2 led to decrease in particle size.