Correlation of Mo dopant and photocatalytic properties of Mo incorporated TiO2: an EXAFS and photocatalytic study

The present study addresses the quantitative estimation and understanding of the nature of phases present in Mo-incorporated titania through extensive EXAFS measurements (at Mo K-edge and Ti K-edge) and to decipher their role in photodegradation of Methylene Blue (MB) dye under UV and visible irradiation. EXAFS results revealed the presence of both MoO3 nano heterophase phase and substitutional Mo dopants in the TiO2 lattice, the extent of the latter was reduced with the increasing Mo content of the sample. The presence of MoO3 in the Mo-incorporated titania was also revealed by FT-IR and TEM studies. Photocatalytic studies have shown considerable adsorption of the cationic MB-dye, perhaps due to the electronic interaction between the dye and catalytic surface. Under visible irradiation, the photocatalytic activity followed the trend: Mo-5 > Mo-2 > Mo-1 > Mo-10 [TiO2, while the trend for photodegradation of MB dye under UV irradiation was as follows: Mo-5 > Mo-2 > Mo-1 > TiO2 > Mo-10. These results have been explained in the light of the structural properties of the Mo-TiO2 system obtained from EXAFS measurements. It has been observed that the relative ratio of substitutional Mo-dopant to the MoO3 phase in this tri-phasic photocatalyst plays a crucial role in augmenting its oxidative photocatalytic property.