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Two-dimensional CoNi nanoparticles@S,N-doped carbon composites derived from S, N-containing Co/Ni MOFs for high performance supercapacitors

Abstract

Owing to controllable morphologies, tunable porous structures, diverse compositions and easy to fabricate, metal organic frameworks (MOFs) have been a class of ideal precursor materials to develop high performance carbon-based materials for energy applications. In this work, two-dimensional (2D) Co/Ni MOFs nanosheets with a molar ratio of Co2+ to Ni2+ of 1:1 were first synthesized in room temperature using thiophene-2,5-dicarboxylate (Tdc) and 4,4ˊ-bipyridine (4,4’-Bpy) as organic linkers. As precursor material, the as-synthesized 2D Co/Ni MOFs nanosheets were further pyrolized at 550 °C in N2 atmosphere to obtain 2D CoNi alloy nanoparticles incorporated into S, N-doped carbon nanosheets (CoNi@SNC) with a surface area of 224 m2 g-1, porous structure, and good conductivity. Interestingly, it was found that 2D Co/Ni MOFs nanosheets can be directly used as electrode material for supercapacitor, delivering a specific capacitance of 312 F g-1 at 1 A g-1, whereas CoNi@SNC derived from its MOFs precursor as electrode material for supercapacitor exhibits much higher specific capacitance (1970, 1897 and 1730 F g-1 at 1, 2, 5 A g-1, respectively) with long cycling life (retaining 95.1% of the value at 10 A g-1 after 3000 cycles) and excellence rate capability at a high charge/discharge current. Further, an asymmetric supercapacitor device was also constructed with CoNi@SNC as the positive electrode and active carbon as the negative electrode, exhibiting an energy density of 55.7 Wh kg-1 at the power denstity of 0.8 kW kg-1 with lifetime stability up to 4000 charge-discharge cycles (capacitance retention of ~90.6%). The results demonstrate that electrochemical activation generated CoNi oxides/oxyhydroxides on the surface of CoNi alloy nanoparticles in alkaline electrolyte during electrochemical measurements should be the electrochemical active species of CoNi@SNC constructued supercapacitor. Besides of that, the high performance of CoNi@SNC constructed supercapacitor could be collectively due to its relatively high surface area favourbale for the exposure of electrochemical active sites, porous structure to promote redox-related mass transport, and CoNi alloy nanoparticles combined with graphitic carbon as electron collector to improve electron transfer.

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Supplementary files

Publication details

The article was received on 01 Feb 2017, accepted on 20 Apr 2017 and first published on 20 Apr 2017


Article type: Paper
DOI: 10.1039/C7TA01008G
Citation: J. Mater. Chem. A, 2017, Accepted Manuscript
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    Two-dimensional CoNi nanoparticles@S,N-doped carbon composites derived from S, N-containing Co/Ni MOFs for high performance supercapacitors

    M. Tong, S. Liu, X. Zhang, W. Tianxing, H. Zhang, G. Wang, Y. Zhang, X. Zhu and H. Zhao, J. Mater. Chem. A, 2017, Accepted Manuscript , DOI: 10.1039/C7TA01008G

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