Different Morphologies of MnO2 Nanostructures for the Photocatalytic Oxidation and Photoreduction

Abstract

This study shows photocatalytic activity of various morphologies of MnO2 nanomaterial prepared via different hydrothermal methods for the photo oxidative decomposition of toxic methylene blue (0.01mM) under solar irradiation and photo reduction of nitrobenzene (25μM) to aniline again under solar irradiation. The resulting materials were characterized by XRD, SEM, EDS, DRS, DLS and fluorescence spectroscopy. MnO2 is a promising photocatalyst for photo oxidation and photoreduction due to its low cost, high stability and low toxicity. Moreover, different shapes exhibit different catalytic activities. Alpha MnO2 nanotubes and beta MnO2 nanorods gives better activity in photo oxidation while alpha nanotubes alone gives better activity in photo reduction. This enhancement in photocatalytic activity is due to different shapes of MnO2 which enlarges its surface area for the reaction. The photo oxidation reaction follows pseudo first order kinetics. GC analysis showed the complete photomineralization of methylene blue to CO2 and H2O