Phase and Shape Dependent Photoactivity of Titania for Nitroaromatics Reduction Under UV Light Irradiation.

This work describes importance of TiO₂ nanostructures of different shapes (nanospheres and nanorods) and crystal phases (anatase and rutile) for the photoreduction of nitroaromatics into corresponding aminoaromatics under UV light irradiation. Anatase nanoparticles were most active of all the catalysts due to the superior stability of this phase and comparatively the rutile nanorods (L×W = 28-30 nm×3.5-3.8 nm) showed superior photoactivity (~3 times) as compared to rutile nanospheres of size 122 nm for the photoreduction due to electron transport along longitudinal length, larger surface area (69 m²g-1), quenched PL emission, increased lifetime of charge carriers (1.8 ns) of rutile nanorods as compare to rutile nanospheres having lower surface area (18 m²g-1) and charge carrier lifetime (1.1 ns). The overall rate of reduction/hour for m-NBA and m-NT photoreduction with all of these catalysts has been found to vary in the following order ANP > P25-TiO₂ > RNR > ANR > RNP.