Synthesis of Long ZnO Nanorods under Microwave Irradiation or Conventional Heating

Abstract

The present work reports the synthesis of zinc oxide (ZnO) nanostructures produced either under microwave irradiation using low cost domestic microwave equipment or by conventional heating, both under hydrothermal conditions. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, room/low temperature photoluminescence, and Raman spectroscopy have been used to investigate the structure, morphology, and optical properties of the produced ZnO nanorods. Identical structures with aspect ratio up to 13 have been achieved for both synthesis routes displaying similar final properties. The hexagonal wurtzite structure has been identified, and a red-orange emission has been detected in the presence of UV irradiation for all the conditions studied. Thermal stability of the as-prepared nanostructures has been evaluated through thermogravimetric measurements revealing an increase of superficial defects. The as-prepared ZnO nanorods were tested as UV sensors on paper substrate, which led to fast response (30 s) and rapid recovery (100 s) times, as well as sensitivity up to 10 indicating that these materials may have a high potential in low cost, disposable UV photodetector applications.

Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study

“…In particular, ZnO nanorods (NRs) have attracted much attention mainly due to their high surface-to-volume ratio and high sensitivity under ambient conditions, thus making them highly appealing for sensing applications [17,18,19]. …”

Effect of solvents on ZnO nanostructures synthesized by solvothermal method assisted by microwave radiation: a photocatalytic study

“…ZnO is a wide direct bandgap semiconductor (3.37 eV at room temperature), with a large free exciton binding energy of 60 meV, leading to efficient exciton emission at room temperature [1,2]. Its applications include thin film and single crystal transistors [3,4], UV/ozone detectors [5,6], light emitting diodes (LEDs) [7,8], phosphorescent glasses [9], piezoelectric devices [10,11], dye solar cells [12,13], photocatalytic agent [14], anti-bacterial and anti-fungal agents [15,16] with different morphologies, like electrodeposition [17,18], electrospinning [19], precipitation [20,21], laser assisted flow deposition (LAFD) [22] and solvothermal and hydrothermal synthesis, whether by conventional heating [23,24] or microwave radiation [25][26][27]. Different synthesis conditions and methods can ensure different ZnO morphologies like wires, pencil-and needle-like rods, flowers, tetrapods, tubes, among other types of particles [28][29][30][31].…”

“…The surfactant solution was prepared by dissolving 0.5 ml of Triton X-100 in 15 ml of de-ionized H 2 O (solution B). The overall reactions for the ZnO nanoparticles solvothermal synthesis and a proposed growth method were previously reported [25,39].…”

One-step synthesis of ZnO decorated CNT buckypaper composites and their optical and electrical properties

“…particles, rods, tetrapods, springs, helixes, belts) with sizes ranging from micro to nano scale [9][10][11]. Several techniques have been employed to grow this semiconductor like colloidal synthesis [12], chemical vapour deposition [13], molecular beam epitaxy [14], thermal evaporation [9], hydrothermal synthesis [15], among others. Due to its high vapour pressure and the fact that this material does not melt, instead decomposes into its atomic components at the temperature of 1977 • C, at atmospheric pressure, the flux methods have been extensively studied [16].…”