Morphological, optical, photocatalytic and electrochemical properties of hydrothermally grown ZnO nanoflowers with variation in hydrothermal temperature

ZnO nanoflowers were synthesized by hydrothermal method. The growth of the nanoflowers was studied for five different hydrothermal temperatures, viz. 100 °C, 120 °C, 140 °C, 160 °C and 180 °C. Morphology, nanostructure and crystalline phase of the prepared samples were characterized by FESEM and XRD. FESEM images show that with change of hydrothermal temperature ZnO nanoflowers grow in size and their petal density also changes. XRD patterns confirm the formation of polycrystalline hexagonal wurzite phase of ZnO powder. Flowers show intense peaks at (100), (002) and (101). UV–Vis absorption spectroscopy of the samples was taken within 200–800 nm. The band gap of the samples was calculated using the Tauc plot relation and its value was found to be around 3.2 to 3.16 eV. Photoluminescence of the samples was taken within 300–700 nm. Emission spectra show variation of intensity of the peak with change in temperature. Photocatalytic degradation of MB dye by the ZnO nanoflowers shows that degradation was greatly influenced by petal thickness and petal density which are changed with change of temperature. Electrochemical activity of the materials is found to be also influenced by hydrothermal temperature.