Perforated ZnO nanoflakes as a new feature of ZnO achieved by the hydrothermal-assisted sol–gel technique

The perforated ZnO nanoflakes with high degree of crystallinity and uniformity were synthesized via the hydrothermal-assisted sol–gel technique without any template. ZnCl2 was used as a Zn-containing precursor, causing the oriented growth of particles. The observation of a hole on the facet of the as-synthesized particles was discussed in this work. XRD, TEM, and DRS were used to investigate the prepared powder and a simple mechanism was suggested to explain the hole formation on the surface of nanoflakes. As a result, the synthesized powder included pure ZnO with direct band gap energy of 3.24 eV. The range of particle size was within 1 lm in diameter and <50 nm in thickness. A circle hole with 300–500 nm in diameter was observed on the facet of the as-synthesized particles.