Enhanced Visible Light Activity of Pr-TiO₂ Nanocatalyst in the Degradation of Dyes: Effect of Pr Doping and TiO₂ Morphology.

Abstract

A facile hydrothermal method was adopted for the synthesis of bare TiO₂ and titania nanotubes (TNT). In an effort to increase the efficacy of the existing photocatalyst, different weight percentage (0.2, 0.4, 0.6, 0.8 and 1.0%) of praseodymium were deftly doped on to the synthesized titania scaffolds. The physicochemical characteristics of the architectured photocatalyst were thoroughly elucidated by various sophisticated techniques. The doping of Pr₂O₃ (Pr) on to titania nanotubes (TNT) resulted into a significant bathochromic/hyperchromic shift in the optical absorption edge (towards the visible region) as perceived from the DRS-UV spectra. The XRD and TEM analysis showed average crystallite size of the synthesised photocatalyst to be as small as 4-7 nm with well-formed nanotube framework. Photoluminescence spectra of Pr doped TNT catalyst clearly exhibited greater suppression of photogenerated electron-hole pair as compared to the undoped counterparts. The photocatalytic activity of the synthesized catalysts was evaluated towards the degradation of organic pollutants namely Rhodamine B (90%) and Crystal violet (93%) in the presence of solar light and its activity and durability was compared to that of commercial TiO₂ (Degussa P25). The observed enhanced photocatalytic activity of TNT and Pr-TNT can be unambiguously attributed to the inhibition of recombination of the electron-hole pairs due to doping of Pr into TNT. Among catalysts synthesized, 0.4 wt.% of Pr on to TNT yielded the highest photocatalytic activity under visible light irradiation.