Colloids and Surfaces A: Physicochem. Eng. Aspects 334 (2009) 160–164 Contents lists available at ScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects journal homepage: www.elsevier.com/locate/colsurfa Preparation and characterization of ZnO nanospindles and ZnO@ZnS core–shell microspindles Fei Li a,b,∗ , Wentuan Bi a , Luoyuan Liu a , Zhen Li a , Xintang Huang b a Faculty of Materials Science and Chemical Engineering, China University of Geosciences, Wuhan 430074, PR China b Center of Nano-Science and Technology, Department of Physics, Central China Normal University, Wuhan 430079, PR China article info Article history: Received 16 May 2008 Received in revised form 9 October 2008 Accepted 14 October 2008 Available online 1 November 2008 Keywords: Core–shell Chemical synthesis Crystal structure Luminescence abstract ZnO nanospindles were synthesized by PVP-assisted hydrothermal growth and ZnO@ZnS core–shell microspindles were successfully fabricated by sulfidation of ZnO nanospindles via a facile chemical syn- thesis. The as-obtained samples were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fluorescence spectrophotometer. The results showed that the pure ZnO nanospindles were hexagonal wurtzite crystal structure and the ZnS nanoparticles were sphalerite structure with the size of about 40 nm grown on the surface of the ZnO nanospindles. The measurement of luminescence revealed that ZnO@ZnS core–shell microspindles integrated the luminescent effect of ZnO and ZnS. The broad blue emission of ZnO@ZnS core–shell microspindles were dramatically enhanced, while the orange emission disappeared. In addi- tion, a possible formation mechanism of ZnO@ZnS core–shell microspindles was also suggested based on the results of the experiments. © 2008 Elsevier B.V. All rights reserved. 1. Introduction As an important II–VI semiconductor with wide band gap and large exciton binding energy, ZnO has unique optical and electronic properties. It is regarded as a promising material applied in opto- electronics [1], varistors [2], chemical sensors [3], catalysts [4], field emission displays [5] and cosmetic [6]. This wide variety of applications requires the fabrication of morphological and surface functional ZnO nanostructures. Modification of ZnO by impurity incorporation and surface coating can efficiently adjust its electri- cal, optical, and magnetic properties [7–9]. Surface coating of ZnO with wide-band-gap semiconductors to form core–shell nanos- tructures has been recognized as one of the most advanced and intriguing methods to improve the luminescence properties of the metal oxide, as demonstrated by ZnO nanorod@CdS nanoparticle core–shell composites [10] and ZnO@CdSe core–shell nanoparticles [11]. ZnS is a well-known luminescent material having prominent applications in flat-panel displays, sensors, and lasers [12], and also has been applied in photocatalysts [13], pigments [14], non-linear ∗ Corresponding author at: School of Materials Science and Chemical Engineering, China University of Geosciences, No. 388, Lumo Road, Wuhan 430074, PR China. Tel.: +86 27 678 83737; fax: +86 27 678 83732. E-mail address: alexfly2002@sina.com (F. Li). optical devices [15] and infrared windows [16]. Because the band gap of ZnS is larger than that of ZnO, the luminescent property of ZnO@ZnS core–shell composites could be improved. Zhao [17] prepared ZnO nanowires by a vapor-phase transport process, and then fabricated ZnO@ZnS core–shell nanowires through the reac- tion of Zn(NO 3 ) 2 and Na 2 S on ZnO nanowires in aqueous solutions. They found that the UV emission of nanorods was dramatically enhanced. Sun et al. [18] had successfully synthesized ZnO@ZnS nanocables through a catalyst-free thermal vapor transport method and investigated its microstructure. In this paper, we presented here a novel two-step chemical route to synthesize large-scale ZnO@ZnS core–shell microspindles via hydrothermal process in low temperature. By this chemical con- version method, large scale ZnO nanospindles could be partially converted to ZnO@ZnS core–shell microspindles. The structure, morphology and luminescence properties were studied in detail and the growth mechanism is preliminarily discussed. 2. Experimental 2.1. Materials All chemicals (Shanghai Chemicals Co. Ltd.) used in this work were of analytical reagent grade and used as received without fur- ther purification. All the aqueous solutions were prepared using double distilled water. 0927-7757/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfa.2008.10.016