Three-dimensional cobalt microspheres composed of nanosheets assembled via facile hydrothermal method
Graphical abstract
Three-dimensional cobalt microspheres composed of nanosheets assembled via facile hydrothermal method.
Introduction
Controlling the structure and morphology of nanomaterials to tailor their chemical and physical properties has become an essential issue in materials science. As a special part of micro- or nano- materials, transition metals with three-dimensional (3D) hierarchical architecture are always attractive for functional materials owing to their unique structure-dependent properties, which have a wide application in various fields, such as electronics, magnetic, sensors, drug delivery, and other areas [1], [2], [3], [4], [5].
The general methodology to achieve 3D hierarchical structures is template-assisted. For instance, Rakhi et al. reported cobalt oxide nanowires grown on carbon fiber paper collectors self-organize into brush-like morphology with the nanowires completely surrounding the carbon microfiber cores [6]. Wang et al. reported the synthesis of multishell cobalt oxide hollow microspheres based on the carbon microspheres as the sacrificial template [7]. These template-assisted methods have demonstrated effectiveness in forming hierarchical materials with various unique shapes. However, most of the procedures are tedious as a result of adding or removing the templates from the reaction systems, which makes reaction process more challenging. Accordingly, the template-free approach appears to be particularly important. There for, fabrication of novel 3D architectures is continuously pursued.
As a typical magnetic metallic material, cobalt has shown unique anisotropic magnetic properties which are crucial for many applications such as magnetic memory devices, magnet sensors, catalysts, etc [8], [9], [10], [11], [12]. In this paper, we report the effective synthesis of 3D cobalt microspheres via facile hydrothermal method without using any hard templates. These as-prepared 3D cobalt microspheres were composed of nanosheets (~18 nm). The crystal structure, morphology, and magnetic properties of the 3D cobalt microspheres were further investigated carefully.
Section snippets
1 Materials and methods
All the chemicals were analytical grade and used in the present work without further purification. In a typical procedure, 4 mmol of Co(NO3)2·4H2O and 1 g of Cetyltrimethyl Ammonium Bromide (CTAB) were dissolved in 60 mL of ethylene glycol with intensive stirring to form a transparent solution at room temperature. Then 4 mL of hydrazine hydrate (80 wt%) was added by dropwise into above solution in 30 min. The obtained precursor was stirred for 1 h, and then transferred to a Teflon-lined autoclave for
Results and discussion
Powder X-ray diffraction was used to determine the chemical composition and crystal structure of the typical synthesized products. Fig. 1a shows the typical XRD pattern of the final product. All the five diffraction peaks of the sample can be perfectly indexed to (100), (002), (101), (102), and (110) crystalline planes corresponding to the hexagonal close-packed (hcp) phase of cobalt (JCPDS no 05-0727, vertical line inset in Fig. 1a), indicating a single phase of the products. No peaks due to
Conclusions
In summary, we have developed a facile hydrothermal method for preparing the 3D cobalt microspheres which composed of nanosheets. The shapes of the final product can be controlled by varying the concentrations of Co(NO3)2·4H2O and surfactants. The XRD spectrum shows that the 3D cobalt microsphere has a hcp phase. The FESEM and TEM results show that the thickness of nanosheets was about 18 nm. The as-obtained products present ferromagnetic properties related to the special morphologies and are
Acknowledgements
This work was supported by the National Natural Science Foundation of China (Grant No. 51403148, 21407111) and Foundation of Suzhou Science and Technology Project (Grant No. SYG201530). Project-sponsored by Qing Lan Project of Jiangsu Province (2016) and the Outstanding Young Teacher of Suzhou University of Science and Technology (2014). The authors are grateful for financial support from Foundation of Shanxi Province Key Laboratory of Functional Nanocomposites, North University of China (No.
References (19)
- et al.
Mater. Lett.
(2012) - et al.
J. Power Sources
(2014) - et al.
Mater. Res Bull.
(2012) - et al.
Electro. Acta
(2012) - et al.
J. Magn. Magn. Mater.
(2002) - et al.
J. Mater. Chem. A
(2014) - et al.
CrystEngComm
(2014) - et al.
Small
(2014) - et al.
Nat. Nanotechnol.
(2014)
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