Synthesis of ZnO by thermal decomposition of different precursors: photocatalytic performance under UV and visible light illumination

Three different zinc oxide (ZnO) samples were obtained from direct thermal treatment of zinc nitrate, zinc carbonate and zinc acetate at 350 °C for 180 min. The obtained samples were characterized by means of XRD, SEM, FTIR, N₂physisorption, DR UV–Vis and Raman spectroscopy. The characterization data showedthe complete dissociation of zinc carbonate and zinc acetate to a pure white powder of ZnO with spheres-like morphology. On the other hand, the thermal treatment of zinc nitrate produced a yellow powder of nitrogen-doped ZnO in a hexagonal pyramidal morphological structure. The photocatalytic activity of the prepared samples was compared with that of commercially available ZnO nanoparticles in the decolourization reaction of methyl green (MG) aqueous solution under the illumination of UV black light (wavelength = 367 nm) and visible light (wavelength >400 nm). The photocatalytic performance of commercial ZnO was dominant under UV light; however, under the illumination of visible light, the nitrogen-doped ZnO sample exhibited the highest activity. (paper)