Preparation of ZnO microstructures by facile hydrothermal route, their PL and PEC Properties

ZnO flower like and doubly pointed microneedles (DPNs) were prepared on Cu₂O and glass substrates respectively via facile hydrothermal route. Cu₂O substrate was prepared through thermal oxidation method from the Cu sheet. The structure and morphologies of ZnO microstructures were characterized by X-ray diffraction and scanning electron microscopy. The average size of flower-like structure was measured to be 2 μm, whereas the doubly pointed microneedles (DPNs) exhibited a tip diameter of 150-250 nm. The flower-like ZnO microstructures showed the photoluminescence emission spectra UV band at 383 nm along with a strong yellow emission band at 580 nm. Correspondingly, the DPNs ZnO microstructure showed UV emission peak at 396 nm associated with a blue emission peak at 469 nm. The photon-to-hydrogen efficiency was found to be 0.04% for flower like microstructure.