NH 4+ directed assembly of zinc oxide micro-tubes from nanoflakes

Abstract

A simple precipitation process followed with the heat treatment was developed to synthesize ZnO micro-tubes by self-assembly of nanoflakes composed of nanoparticles. The resulting ZnO micro-tubes demonstrated excellent photocatalytic performance in degrading methylene blue (MB) under UV illumination. It was found that NH 4+ ion played a critical role in directing the assembly of the nanoflakes to form the micro-tube structure. A critical reaction ratio existed at or above which the ZnO micro-tubes could be obtained. For the mixtures of solutions of (NH 4) 2CO 3 and zinc salt, the ratio (C (NH4)2 CO3/C Zn2+) was 2:1. © 2011 Yang et al.