Investigating the effects of hydrothermal temperature on morphology-controlled synthesis of flower-shaped ZnO microstructures

The hydrothermal synthesis and morphology-dependent properties of flower-shaped ZnO microstructures have been extensively described in this study. The growth of flower-shaped ZnO microstructures has been conducted in HMT aqueous solutions containing zinc nitrate tetrahydrate precursor in three different hydrothermal temperatures (100 °C, 150 °C, and 200 °C). Morphological observations and structural analysis have been performed using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FT-IR), and Raman spectroscopy. Morphological studies have indicated a transition from sheet-like petals to rod-like structures for flower-shaped architectures with the increase of reaction temperatures. XRD patterns have revealed single-crystalline behavior for as-synthesized ZnO microstructures. Crystalline quantities have been investigated using a variety of X-ray line broadening analysis techniques including Debye-Scherrer and Williamson-Hall methods. UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) has been employed to carry out the optical studies and estimate optical band gap energies. The optical results have suggested morphology-dependent responses for flower-shaped ZnO microstructures.