Eco-Friendly, Highly Efficient Ethanol-Assisted Supercritical Preparation of an Ultrathin ZnO Nanotube

Abstract

The nanotubes widely used in the advanced semiconductor manufacturing field suffer from complicated timeand energy-consuming synthesis processes, thus requiring an efficient preparation method. In this study, ethanol-assisted supercritical treatment (SC-EA), a sustainable approach with less environmental hazard, has been applied to efficiently synthesize ZnO nanotubes. Materials free from any detrimental effect on the environment have been utilized in the proposed ethanol−water mixed supercritical fluid technique to realize nanotube growth. High synthetic efficiency, eco-friendly processing, and an ultrasimple procedure are achieved in the SC-EA treatment at a low temperature and with a low preparation cost. The analysis results from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) collectively confirm the successful synthesis of ZnO nanotubes with an ultrathin crystalline wall of only 3 nm. A chemical reaction model is established for a better understanding of the SC-EA process in which ethanol molecules act as the surfactants to help ZnO nanotubes grow by forming nanocells. Such a green supercritical methodology, by means of an eco-friendly synthesis system in achieving CO 2 reutilization and recycling, provides a bright future to modulate a variety of nanostructured materials in a facile and efficient way.

Controlled Synthesis of Large-Area Oriented ZnO Nanoarrays

“…Therefore, ZnO nanoarrays have become one of the key materials in the field of optoelectronics [ 16 , 17 , 18 , 19 ]. Many methods have been used to synthetize ZnO nanoarrays, such as chemical, electrochemical, and physical deposition techniques [ 20 , 21 , 22 , 23 ]. Some studies have shown that the photoelectric properties of ZnO nanoarrays are closely related to the morphology of one-dimensional ZnO nanostructures (including nanowires, nanobelts, nanotubes, etc.)…”

Role of Post-Hydrothermal Treatment on the Microstructures and Photocatalytic Activity of TiO2-Based Nanotubes

“…Nanotubes have been a popular one-dimensional allotropic form of carbon in the scientific domain. Currently, a wide variety of nanotubes composed of various different elements, such as carbon, titanium, tungsten, zinc, etc., have attracted the attention of scientists [1][2][3][4]. It has been established that a wide range of layered materials can form nanotubes since the discovery of nanotube morphology [5].…”