Investigation of Structural, Optical, and Photocatalytic Properties of Hydrothermally Synthesized ZnO Nanorod Arrays with Various Aspect Ratios

Abstract

Zinc oxide (ZnO) nanorods (NRs) with various aspect ratios (by changing the growth time between 0-240 min) were synthesized using hydrothermal method and were investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and UV–Visible and photoluminescence (Pl) spectroscopies. It was found that growth time is directly related to the length, orientation and aspect ratio of the NR arrays. The optical transmittance of NR arrays indicated a regular decrement of average transmittance with increasing the length and aspect ratio of the NRs in the visible range. The porous ZnO nanorod grown for 240 min with the thickness of ∼ 1.56 μm and texture coefficient of 0.96 exhibits some interesting properties like average visible transmittance of ~ 60%, refractive index of 1.34, packing density of 0.26 and lowest optical band gap. As the growth time increased, the PL intensity sustained a general weakening and a red-shift of UV-emission peak position. The UV-assisted photocatalytic degradation of 4- Nitrophenol (4-NP) of ZnO NRs were investigated. The considerable photocatalytic performance of ZnO NRs with highest aspect ratio was explained by its porosity and optical characteristics.