Reproducibility and long-term stability of Sn doped MnO₂ nanostructures: Practical photocatalytic systems and...

Sn-doped MnO₂ were synthesized as an oxidant, a mediator of maleic acid (C₄H₄O₄) and SnCl₂ as doping ingredient via a basic sol-gel reaction with KMnO₄. XRD study signposts that tetragonal crystal structure of MnO₂ (ICDD#44-0141) with a plane group of 12/m (87) for both pure and Sn doped MnO₂ nanostructures. The photocatalyst synthesized has mesoporosity, allowing to the N₂ adsorption/desorption experiments. The geometry of the materials varies from spherical shape in pristine MnO₂ to a rod-like shape in Sn-MnO₂, as observed in the SEM and TEM pictures. To examine optic properties and energy bandgaps topologies, UV-visible diffuse reflectance spectroscopy was applied. In visible spectrum, overall catalytic performance of Sn-doped MnO₂ was tested using methyl orange and phenol as dyes. The results suggest that the optimized Sn doped MnO₂ (10 wt.%) catalyst showed higher degradation efficiency (98.5%), apparent constant (0.7841 min^-1) and long term permanence. For this improved charge extraction efficiency, a potential photocatalytic mechanism was proposed.