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

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 O-2 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 O-2 only. Microwave absorption properties of the ZnO nanostructures have been investigated, the value of minimum reflection loss for the composite with 40 vol% ZnO hierarchical tree-like nanostructures is -27.5 dB at 5 GHz with a thickness of 4.0 mm. (C) 2013 Elsevier B.V. All rights reserved.