Facile Synthesis of Rambutan-Like ZnO Hierarchical Hollow Microspheres with Highly Photocatalytic Activity

Ke-Jian Ju,Ai-Jun Wang,Jie Wei,Qian-Li Zhang,Ming Zhang

doi:10.1155/2015/242798

Abstract

Rambutan-like ZnO hierarchical hollow microspheres (ZnO HHMs) were constructed under hydrothermal conditions, using carboxyl methyl starch (CMS) as a soft template. The resulting products were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental parameters and growth mechanism of rambutan-like ZnO HHMs were discussed in some detail. The as-prepared samples displayed improved photocatalytic activity for the degradation of rhodamine B under ultraviolet (UV) irradiation.

Highlights

ZnO has attracted global interest as a promising alternative semiconductor to TiO2 in dye-sensitized solar cells, owing to its direct wide band gap (3.37 eV) and high electron mobility (17 cm2 ⋅ V−1 ⋅ s−1) for single-crystal ZnO nanostructures [1, 2]
As illustrated by the X-ray diffraction (XRD) pattern of typical ZnO hierarchical hollow microspheres (HHMs) (Figure 1(d)), all the diffraction peaks are well indexed to the wurtzite hexagonal ZnO with lattice constants a = 3.249 Aand c = 5.207 A (JCPDS card 36-1451) [25, 26], respectively
The density of the nanorods on the surfaces of ZnO HHMs drops down at 140∘C (Figure 6(c)), and broken bald spheres show up as the temperature is up to 160∘C (Figure 6(d)). These results demonstrate that the rates of the nucleation and crystal growth are sensitive to the reaction temperature [22]

Summary

Introduction

ZnO has attracted global interest as a promising alternative semiconductor to TiO2 in dye-sensitized solar cells, owing to its direct wide band gap (3.37 eV) and high electron mobility (17 cm2 ⋅ V−1 ⋅ s−1) for single-crystal ZnO nanostructures [1, 2]. One-dimensional (1D) ZnO nanostructures such as nanowires and nanotubes have been prepared to reduce recombination phenomena upon the electron transport process and improve the electron collection efficiency [15]. These 1D structures suffer from a rather low specific surface area. Flower-like and double-caged peanut-like ZnO hollow structures were prepared in our group [21, 22], which showed enhanced surface area and improved catalytic activity. Journal of Nanomaterials synthesis of rambutan-like ZnO hierarchical hollow microspheres (HHMs) under low temperature (120∘C) without the calcination procedure, using carboxyl methyl starch (CMS) as a soft template. The catalytic activity of the resulting product was examined by the photodegradation of rhodamine B as a model system

Experimental Section

Results and Discussion

Conclusions