Catalytic induced morpholical transformation of porous ZnO to ZnO nanorods by Sn(IV) and their effect on photocatalytic reduction of methylene blue and DFT calculations.

In this work, a new method for the preparation of ZnO hexagonal nanocrystals by using Sn(IV) as a catalyst was established, which resulted in tranformation of Porous to nanorod-like structures of ZnO. X–ray diffraction (XRD), Energy Dispersion X–ray analysis (EDX), and FT–IR measurements showed that all ZnO nanostructures were of hexagonal phase structure. Transmission electron microscopy (TEM) and scanning electron microscopic (FESEM) studies revealed that morphology of porous–like ZnO (100–200 nm) was converted into nanorod-like (length ~2 μm, diameter ~80 nm) structures upon addition of Sn(IV) as a catalyst. Spectroscopic studies demonstrated that the Zinc(II) compound yields high–quality porous ZnO which upon addition of Sn(IV) catalyst changes into crystalline hexagonal nanorods. The band gap of ZnO nanoparticles calculated employing UV spectrum was found to be 3.31 eV. Moreover, the photocatalytic degradation of methylene blue (MB) under UV light irradiation was performed, which confirmed higher photodegradation of hexagonal ZnO than porous ZnO nanostructures. Furthermore, DFT/TDDFT calculations of MB dye and the expected photodegradation product were also assessed, which were consistent with the kinetic studies. Additionally, zeta potential of the ZnO nanoparticles was measured in the dispersion medium of SDS surfactant which supported high stability of particles are in solution.