Tailoring Morphology of ZnO Nanostructures on Fabrics By Electrochemical Deposition for Gas Sensors

With significant advancements in field of nanotechnology, people are more interested in implementing the nanotechnology into practical and portable devices such as flexible and wearable devices. Research is actively focused on utilizing flexible substrates instead of solid and rigid substrates while sustaining excellent material properties to realize commercialization. For wearable devices, functional materials such as semiconductors need to be built on fabrics and/or fibers. Among various semiconducting materials, ZnO is an excellent candidate for many applications because of their facile fabrication of nanostructure and structure-driven electronic and optical properties.

There are many methods to fabricate ZnO nanostructures, but solution synthesis can be the most simple and effective way to construct ZnO on wearable substrates. Various parameters in solution process such as precursors, temperature, and pH have been investigated to change ZnO nanostructure and to understand the growth mechanisms. However, solution process with electrical bias on the morphological evolution has been rarely investigated. In addition, realization of ZnO nanostructures on various fabrics still remains as a key challenge for wearable electronics.

Therefore, we designed and investigated a simple solution method to control the morphology of ZnO nanostructures by applying external voltage on copper coated polyester taffeta fabrics. In addition, types of ZnO precursors in solution and types of fabrics were systematically investigated to determine the bias-driven morphology. The use of external voltage promotes nucleation of ZnO nanorods without ZnO seed layer. With the increase of external voltage, ZnO nanorods became agglomerate structures. The degree of agglomerates varies depending on the types of fabrics. Such comparative study in substrate effects provide insight on the growth mechanism in electrochemical deposition. Gas sensing properties of various ZnO nanostructures on fabrics are compared in detail.