title: Kinetically controlled synthesis of wurtzite ZnS nanorods through mild thermolysis of a covalent organic-inorganic network.
abstract: The high-temperature (over 1020 degrees C) polymorph of ZnS, wurtzite ZnS, has been successfully prepared through a low-temperature (180 degrees C) hydrothermal synthesis route in the presence of ethylenediamine (en). The effects of en concentrations, reactant concentrations, reaction temperatures, and reaction times on crystal structures and shapes of ZnS have been investigated. We have demonstrated that the wurtzite ZnS showing rodlike morphology can be kinetically stabilized in the presence of en, especially at a high reactant concentration under appropriate hydrothermal conditions. Besides phase evolution of ZnS from hexagonal to cubic, morphological transformation from nanorods to nanograins has also been observed in the present investigation. Nanograins of phase-pure cubic ZnS, the thermodynamically stable polymorph, are easily prepared, and no hexagonal ZnS nanorods are detected in "pure" water, i.e., in the absence of en molecules. The above investigations indicate that the controlled fabrication of wurtzite ZnS nanorods is due to a mediated generation of the lamellar phase, ZnS.0.5en, a covalent organic-inorganic network based on ZnS slabs, and to its subsequent thermolysis in aqueous solution. The controlled growth of wurtzite ZnS nanorods and sphalerite ZnS nanograins provides us an opportunity to structurally modulate physical properties. These wurtzite ZnS nanorods display narrower and stronger blue emission than sphalerite ZnS nanograins.
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275, P. R. China.
authors.forename: Xijian
authors.initials: X
authors.lastname: Chen
authors.forename: Huifang
authors.initials: H
authors.lastname: Xu
authors.forename: Ningsheng
authors.initials: N
authors.lastname: Xu
authors.forename: Fenghua
authors.initials: F
authors.lastname: Zhao
authors.forename: Wenjiao
authors.initials: W
authors.lastname: Lin
authors.forename: Gang
authors.initials: G
authors.lastname: Lin
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Fu
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Huang
authors.forename: Hezhou
authors.initials: H
authors.lastname: Wang
authors.forename: Mingmei
authors.initials: M
authors.lastname: Wu