One-step synthesis and excellent microwave absorption of hierarchical tree-like ZnO nanostructures

Abstract

A large area of uniform and intriguing ZnO hierarchical tree-like nanostructures have been synthesized by a simple one-step chemical vapor deposition(CVD) process using pure zinc powder and O2 gas as source materials. ZnO nanowires grow on the silicon substrate while the reactions take place, and then regular nanorods grow uniformly on the ZnO nanowires to form tree-like nanostructures by increasing the flow rate of O2 only. Microwave absorption properties of the ZnO nanostructures have been investigated, the value of minimum reflection loss for the composite with 40vol% ZnO hierarchical tree-like nanostructures is −27.5dB at 5GHz with a thickness of 4.0mm.