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Browsing Articles by Author "Bakenov, Zhumabay"

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    MoS2 nanopowder as anode material for lithium-ion batteries produced by self-propagating high-temperature synthesis
    (2017-01-01) Bozheyev, Farabi; Zhexembekova, Anar; Zhumagali, Shynggys; Molkenova, Anara; Bakenov, Zhumabay; Farabi, Bozheyev
    Abstract Due to continuous rise of demand for powerful energy sources for portable applications, high energy density and efficiency rechargeable batteries are under constant development. Currently, the most widely used power source for such applications is rechargeable lithium-ion batteries (LIBs). To increase the energy density, rate capability and cyclability of LIBs, alternative anode materials, such as MoS2, are under intensive investigation. The layered structure of MoS2 resembles graphite, and its theoretical specific capacity is about twice higher than that of graphite (670 mAh g-1 against 372 mAh g-1) due to its higher interlayer spacing (∼0.6 nm) for a Li-ion intercalation. In this work MoS2 nanopowder (MoS2-NP), prepared by self-propagating high-temperature synthesis (SHS), is used as an anode material (MoS2/C composition) for LIBs, and its electrochemical properties were analyzed. The MoS2-NP anode exhibited the initial charge capacity of 567 mAh g-1 at a current density of 50 mAh g-1. This performance will be improved by introduction of MoS2-NP into various carbon-containing composites.
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    Thiol-modified activated carbon material for sensor technology
    (2017-01-01) Zhexembekova, Anar; Akhmetova, Nuriya; Molkenova, Anara; Bakenov, Zhumabay; O'Hare, Danny; Anar, Zhexembekova
    Abstract Activated carbon (AC) is a material of great potential in production of membranes for a construction of novel electrochemical sensors due to highly microporous structure and greater surface area per unit volume [1]. Herein we report the production of thiol-modified activated-carbon-based composite. It was obtained by treatment of ketjen black (KB) with concentrated nitric acid (69 wt.%) and further mixing with sulfur (5 wt.%) through high-energy ball milling process. The obtained composite underwent two-stage heat treatment in a tubular furnace under an atmosphere of Ar followed by 4% H2 in N2. All samples were characterized using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The presence of thiol functional was validated by absorbance peaks at around 665 cm-1 and 2360 cm-1. As revealed by TGA, sulfur doped activated KB (KB/S) underwent significant mass loss (70.5%) compared with KB (0.8%), which corresponds to an increase in the effective surface area.
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    Thiol-modified activated carbon material for sensor technology
    (2017-01-01) Zhexembekova, Anar; Akhmetova, Nuriya; Molkenova, Anara; Bakenov, Zhumabay; O'Hare, Danny; Anar, Zhexembekova
    Abstract Activated carbon (AC) is a material of great potential in production of membranes for a construction of novel electrochemical sensors due to highly microporous structure and greater surface area per unit volume [1]. Herein we report the production of thiol-modified activated-carbon-based composite. It was obtained by treatment of ketjen black (KB) with concentrated nitric acid (69 wt.%) and further mixing with sulfur (5 wt.%) through high-energy ball milling process. The obtained composite underwent two-stage heat treatment in a tubular furnace under an atmosphere of Ar followed by 4% H2 in N2. All samples were characterized using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The presence of thiol functional was validated by absorbance peaks at around 665 cm-1 and 2360 cm-1. As revealed by TGA, sulfur doped activated KB (KB/S) underwent significant mass loss (70.5%) compared with KB (0.8%), which corresponds to an increase in the effective surface area.