Rutile-TiO2: Post heat treatment and its influence on the photocatalytic degradation of MB dye

Abstract

Photocatalytic degradation of hazardous Methylene blue (MB) attracts greater concern as it is the dominant effluent of textile industry that is mixing with the ground water resources. In this regard, we have explored the possibility for an efficient optimization of MB dye degradation using rutile TiO2. We have studied the post heat treatment of faceted Rutile TiO2 nano crystallites synthesized by sol-gel method, which was carried out towards understanding the generation of surface states and its role on the dye degradation. The phase purity and its morphological structures were confirmed by XRD, Raman analysis, FESEM and HRTEM. The XPS analysis reveals the passivation of Ti3+ defect upon high temperature treatment above 600 ᵒC and also found generating surface defect states which are evidenced from the photoluminescence study. An EPR investigation clearly reveals the distributed presence of electron and hole trap states in the faceted R–TiO2 nano crystallites. Corresponding EIS measurement of flat band potential of the electrochemical interface between R–TiO2/NaCl shows the upward band bending of R–TiO2 favourable for the improved charge transfer between R–TiO2 to Methylene blue (MB) dye. The consolidated results indicate that the high temperature treatment passivates the Ti3+ defects and promotes the generation of surface defects that favourably enhances the photocatalytic performance of MB dye from 63% to 90%. The details are discussed in this paper.