Piezoelectric and field emitted properties of controlled ZnO nanorods on CNT yarns

ZnO nanorods were synthesized on carbon nanotube (CNT) yarns by an electrochemical deposition method. The grown ZnO shapes varied from a sharp cone-type nanorod to a hexagonal type nanorod according to the increase of counter electrodes. A hexagonal type nanorod changed about 0.3% of its static dimension when it was exposed to an external electric field. From an external pressure with a constant force is applied to the hexagonal type ZnO nanorods, a voltage was generated from 7.5 mV to 10 mV. A cone-type nanorod showed a remarkable field emission whose threshold voltage was as low as 1.5 V/μm. As the results of piezoelectric and field emission tests, the ZnO nanorods on CNT yarn could be a useful material in the applications of a power generator and an emitter.

Graphical abstractDifferent shapes of ZnO nanorods: hexagonal type of ZnO nanorods (a) and their piezoelectric properties (b), corn-type of ZnO nanorods (c) and their field emission results (d).Figure optionsDownload full-size imageDownload as PowerPoint slide