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Issue 17, 2016
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Symmetric pseudocapacitors based on molybdenum disulfide (MoS2)-modified carbon nanospheres: correlating physicochemistry and synergistic interaction on energy storage

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Abstract

Molybdenum disulfide-modified carbon nanospheres (MoS2/CNS) with two different morphologies (spherical and flower-like) have been synthesized using hydrothermal techniques and investigated as symmetric pseudocapacitors in an aqueous electrolyte. The physicochemical properties of these MoS2/CNS layered materials have been investigated using surface area analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FTIR) spectroscopy, and advanced electrochemistry, including cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), long-hour voltage-holding tests, and electrochemical impedance spectroscopy (EIS). The two different MoS2/CNS layered materials exhibit unique differences in morphology, surface area, and structural parameters, which have been correlated with their electrochemical capacitive properties. The flower-like morphology (f-MoS2/CNS) shows lattice expansion (XRD), large surface area (BET analysis), and small-sized nanostructures (corroborated by the larger FWHM of the Raman and XRD data). In contrast to the f-MoS2/CNS, the spherical morphology (s-MoS2/CNS) shows lattice contraction and small surface area with relatively large-sized nanostructures. The presence of CNS on the MoS2 structure leads to slight softening of the characteristic Raman bands (E12g and A1g modes) with larger FWHM. MoS2 and its CNS-based composites have been tested in symmetric electrochemical capacitors in an aqueous 1 M Na2SO4 solution. CNS improves the conductivity of the MoS2 and synergistically enhances the electrochemical capacitive properties of the materials, especially the f-MoS2/CNS-based symmetric cells (most notably, in terms of capacitance retention). The f-MoS2/CNS-based pseudocapacitor shows a maximum capacitance of 231 F g−1, with high energy density 26 W h kg−1 and power density 6443 W kg−1. For the s-MoS2/CNS-based pseudocapacitor, the equivalent values are 108 F g−1, 7.4 W h kg−1 and 3700 W kg−1. The high-performance of the f-MoS2/CNS is consistent with its physicochemical properties as determined by the spectroscopy and microscopy data. These findings have opened doors for further exploration of the synergistic effects between MoS2 graphene-like sheets and CNS for energy storage.

Graphical abstract: Symmetric pseudocapacitors based on molybdenum disulfide (MoS2)-modified carbon nanospheres: correlating physicochemistry and synergistic interaction on energy storage

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Supplementary files

Article information


Submitted
05 Jan 2016
Accepted
23 Mar 2016
First published
24 Mar 2016

This article is Open Access

J. Mater. Chem. A, 2016,4, 6411-6425
Article type
Paper

Symmetric pseudocapacitors based on molybdenum disulfide (MoS2)-modified carbon nanospheres: correlating physicochemistry and synergistic interaction on energy storage

T. N. Y. Khawula, K. Raju, P. J. Franklyn, I. Sigalas and K. I. Ozoemena, J. Mater. Chem. A, 2016, 4, 6411
DOI: 10.1039/C6TA00114A

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