Growth Parameters for Films of Hydrothermally Synthesized One-Dimensional Nanocrystals of Zinc Oxide

Abstract

Zinc oxide has been the focus of material research due to its potential applications in a variety of novel fields. The material exhibits anisotropic growth in the form of single crystal rods/wires of length in microns and thickness in several tens of nanometers through a facile and low temperature hydrothermal route wherein size, morphology, orientation, and growth rate are strongly dependent on a number of synthesis parameters. In this review article we intend to present/discuss the effects of important growth parameters of zinc oxide that have been reported in the literature. These parameters include concentration of the precursor solution, growth time, role of hexamine, synthesis temperature, pH of the precursor, and seeding layer deposited on a substrate.

Synthesis and Characterization of Mesoporous Zinc Oxide Nanoparticles

“…The homogenous growth of ZnO particles was observed at a threshold pH value [30]. Similarly, the size of ZnO particles increased with increase in hydrothermal temperature [37], whereas, decreased with precursor concentration [38]. Furthermore, calcination temperature removed the organic compounds, thus produced the pure crystalline structure of ZnO nanoparticles [29].…”

“…Among these techniques, the hydrothermal route has been a versatile method owing to several advantages including the formation of novel nanohybrid and nanocomposite materials [33], low-temperature synthesis, cost-effective, strong capacity for scale-up [34] and high temperature-sensitive applications could be created [35]. Furthermore, hydrothermal synthesis of ZnO nanoparticles critically depends on varied synthesis parameters such as molar concentration [36,38] and pH value [30] of precursors, hydrothermal temperature [37] and calcination temperature [29] etc. For instance, an increase in molar concentration of precursors increased to both degree of crystallinity and crystal size of ZnO nanoparticles [36].…”

The role of counter-ions in crystal morphology, surface structure and photocatalytic activity of ZnO crystals grown onto a substrate

“…Over the past decade, several synthesis methodologies have been used to explore and optimize the ZnO compound, allowing the obtainment of a variety of properties with precise control over the morphological features [16,22,23,[28][29][30]. Among such routes, the conventional hydrothermal treatment has several advantages related to its technical convenience in obtaining well-structured ZnO crystals grown directly onto a substrate by means of relatively low-temperature treatment [30][31][32][33][34][35].…”

“…Over the past decade, several synthesis methodologies have been used to explore and optimize the ZnO compound, allowing the obtainment of a variety of properties with precise control over the morphological features [16,22,23,[28][29][30]. Among such routes, the conventional hydrothermal treatment has several advantages related to its technical convenience in obtaining well-structured ZnO crystals grown directly onto a substrate by means of relatively low-temperature treatment [30][31][32][33][34][35]. The morphological and surface properties of these nanostructures can be controlled by the optimization of some synthesis parameters, such as precursor concentration, source (distinct counterions), solvent, temperature and reaction time, among others [29,30,33,[35][36][37][38][39].…”

Optical and structural properties of synthesized ZnO nanorods through chemical bath deposition on various substrates

“…ZnO nanostructures have unique properties, such as wide and direct band gap (3.37 eV), large exciton binding energy (60 meV) at room temperature [5], high electron mobility, high transparency, and high thermal conductivity [6]. It is an important kind of technological semiconductor due to its characterized optical, electrical, and piezoelectrical properties, which can be commonly used in optoelectronic, sensors, piezoelectric devices, field emission, luminescence, nanogenerators and photovoltaic devices [7,8]. ZnO nanomaterials can be fabricated using several methods, such as pulsed laser deposition [9], chemical bath deposition(CBD) [10], chemical vapor deposition, sputtering, hydrothermal [11], spin coating [12], sol-gel [13], and others.…”