Self-Etching-Induced Morphological Evolution of ZnO Microrods Grown on FTO Glass by Hydrothermal Method.

Wen-Dung Hsu,Tian-Chiuan Wu,Yan-Kuan He,Jenn-Kai Tsai,Teen-Hang Meen,Yu-Da Lai

doi:10.1186/s11671-015-1140-8

Abstract

In this research, the zinc oxide (ZnO) microrods were grown by hydrothermal method on fluorine-doped tin oxide (FTO) glass functionalized by self-assembled monolayer of octadecyltrimethoxysilane (ODS; CH3(CH2)17Si(OCH3)3). The sharp-tip or polygonal shape with specific facets at the top end of ZnO microrods can be obtained by post retention at low temperature. The morphologies were characterized by the field-emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM). The results confirm that the morphology change at the top end is due to self-etching. The mechanism responsible for the formation of various top-end morphologies was proposed. The specific facets that left after 6-h retention were identified. The room-temperature micro-photoluminescence spectra showed a strong ultraviolet emission at 387 nm, and a broad emission at a range of from 500 to 700 nm. The morphology change also influences the photoluminescence (PL) spectra. A satellite peak in the UV emission spectra was observed. The peak may be attributed to the morphology effect of the microrods.

Highlights

In recent years, controlling the morphology and size of zinc oxide (ZnO) nanomaterials has attracted intensive attentions
ZnO microrods were synthesized on fluorine-doped tin oxide (FTO) substrates using zinc nitrate and hexamethylenetetramine by hydrothermal method
The top-end morphology of microrods can be changed by post retention at low temperature after hydrothermal growth

Summary

Introduction

In recent years, controlling the morphology and size of ZnO nanomaterials has attracted intensive attentions. ZnO is one of II–VI semiconductors with a direct band gap of 3.37 eV. Different ZnO structures can be applied to different fields, various synthesis methods, such as chemical vapor deposition [14, 15], vapor transport deposition [16], magnetron sputtering method [17], and hydrothermal method [10, 18] have been reported to produce different ZnO nanostructures. Producing morphology controllable ZnO nanomaterials by cost-efficient methods, is still a challenge. Hydrothermal method is one of highly promising methods to fulfill the demand because of its low synthesis temperature, low cost, less complicated technique, and good potential for scale-up

Methods

Results

Conclusion