Research Institute of renewable energy, energy saving, efficiency and future energy

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Browsing Research Institute of renewable energy, energy saving, efficiency and future energy by Author "Li, Haipeng"

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    Fabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD
    (Nanoscale Research Letters, 2016-09-27) Li, Haipeng; Li, Yue; Zhang, Yongguang; Liang, Chunyong; Wang, Hongshui; Li, Baoe; Adair, Desmond; Bakenov, Zhumabay
    Carbon-encapsulated cobalt (Co@C) nanoparticles, with a tunable structure, were synthesized by chemical vapor deposition using Co nanoparticles as the catalyst and supported on a water-soluble substrate (sodium chloride), which was easily removed by washing and centrifugation. The influences of growth temperature and time on the structure and magnetic properties of the Co@C nanoparticles were systematically investigated. For different growth temperatures, the magnetic Co nanoparticles were encapsulated by different types of carbon layers, including amorphous carbon layers, graphitic layers, and carbon nanofibers. This inferred a close relationship between the structure of the carbon-encapsulated metal nanoparticles and the growth temperature. At a fixed growth temperature of 400 °C, prolonged growth time caused an increase in thickness of the carbon layers. The magnetic characterization indicated that the magnetic properties of the obtained Co@C nanoparticles depend not only on the graphitization but also on the thickness of the encapsulated carbon layer, which were easily controlled by the growth temperatures and times. Optimization of the synthesis process allowed achieving relatively high coercivity of the synthesized Co@C nanoparticles and enhancement of its ferromagnetic properties, which make this system promising as a magnetic material, particularly for high-density magnetic recording applications.
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    Simple One-Pot Synthesis of Hexagonal ZnO Nanoplates as Anode Material for Lithium-Ion Batteries
    (Copyright © 2016 Haipeng Li et al., 2015-12-15) Li, Haipeng; Wei, Yaqiong; Zhao, Yan; Zhang, Yongguang; Yin, Fuxing; Zhang, Chengwei; Bakenov, Zhumabay
    Hexagonal ZnO nanoplates were synthesized via simple one-pot hydrothermal reaction of Zn(CH3COO)2 and CO(NH2)2. XRD, SEM, and HRTEM were used to investigate the composition and microstructure of the material. Together with the facile strain relaxation during structure and volume change upon cycling, this plate-like structure of ZnO is favorable for physical and chemical interactions with lithium ions because of its large contact area with the electrolyte, providing more active sites and short diffusion distances.The resulting hexagonal ZnO nanoplates electrode exhibited good cyclability and delivered a reversible discharge capacity of 368mAh g−1 after 100 cycles at 0.1 C.
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    Synthesis of hierarchical MoS2 microspheres composed of nanosheets assembled via facile hydrothermal method as anode material for lithium-ion batteries
    (Springer Science+Business Media Dordrecht 2016. J Nanopart Res (2016) 18:63, 2016-02-24) Zhang, Yongguang; Li, Yue; Li, Haipeng; Yin, Fuxing; Zhao, Yan; Bakenov, Zhumabay
    A hierarchical MoS2 architecture composed of nanosheet-assembled microspheres with an expanded interplanar spacing of the (002) planes was successfully prepared via a simple hydrothermal reaction. Electron microscopy studies revealed formation of the MoS2 microspheres with an average diameter of 230 nm. It was shown that the hierarchical structure of MoS2 microspheres possesses both the merits of nanometer-sized building blocks and micrometer-sized assemblies, which offer high surface area for fast kinetics and buffers the volume expansion during lithium insertion/deinsertion, respectively. The micrometer-sized assemblies were found to contribute to the enhanced electrochemical stabilities of the electrode materials....