Facile Continuous Flow Injection Process for High Quality Long ZnO Nanowire Arrays Synthesis

Abstract

This paper reports a facile continuous flow injection (CFI) process to synthesize high-quality long zinc oxide nanowire arrays (ZnO-NAs) using a hydrothermal method. In previous related studies, the photoluminescence (PL) spectra of ZnO-NAs synthesized using a batch process exhibit highly visible emission caused by defect structures. In contrast to the batch process, zinc oxide nanowire arrays grown using the CFI process can reduce the visible emission in PL spectra effectively, demonstrating the qualities of zinc oxide nanowire arrays as superior to those grown using a batch process. To understand the difference between batch processes and the CFI process, inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to analyze the zinc precursor concentration regarding growth duration. According to the concentration variation of both processes, we could determine that zinc precursor concentration is maintained at a constant level to promote ZnO-NAs growth continuously in the CFI process. Long ZnO nanowire arrays can be obtained easily using the CFI process. The results demonstrate that the CFI process is a facile process for growing high-quality long ZnO nanowire arrays.

General Route to ZnO Nanorod Arrays on Conducting Substrates via Galvanic-cell-based approach

“…This orange-red emission is attributed to radiative transitions involving defect-induced energy levels located in the band gap, and is assumed to involve interstitial oxygen ions (O i ). However, our samples do not display such orange-red emission, which indicates the high optical quality and low defects density of the as-grown ZnO nanorods40.…”

Metal Oxide Nanoarrays for Chemical Sensing: A Review of Fabrication Methods, Sensing Modes, and Their Inter-correlations

“…It is worth pointing out that all these above-mentioned examples are based on planar sample surface or 2D surface deposition, where mass transport issue will not be considered in general. However, when considering non-planar surface or 3D surface, the typical batch based static hydrothermal growth method would be prevented by the difficulty of mass transport within confined 3D space, resulting into the poor coverage of nanoarrays throughout the deposition substrate (Chen and Yin, 2012;Liu et al, 2014). A typical hydrothermally based continuous flow synthesis (CFS) method has been reported by Wang et al (2017) to synthesize uniform ZnO nanorod arrays on 3-D honeycomb substrates.…”

Rational Design of Photoelectrodes with Rapid Charge Transport for Photoelectrochemical Applications

“…The continuous flow injection (CFI) process is another approach that has been reported to grow long ZnO nanowires. [126] Using this approach, fresh precursors with controlled flow rates can be continuously supplied; thus, the growth rate, diameter, and density can be readily tailored. [127] Feng's group recently reported the synthesis of well-separated single-crystal rutile TiO 2 nanowire arrays with lengths up to ~10 µm by effectively suppressing their lateral growth.…”

“…Recently, Chen and coworkers synthesized 25-m-long ZnO nanowire arrays using a CFI process. [126,134] They further increased the surface area by decorating the nanowires with ZnO nanoparticles and achieved a solar to electricity conversion efficiency of 6.8%. [234] These results indicate that the growth of single-crystal long ZnO nanowire arrays is important for solar cell applications.…”