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Hybrid NiO-CuO mesoporous nanowires array with abundant oxygen vacancies and hollow structure for high-performance asymmetric supercapacitor

Abstract

High specific capacity as well as good cycling stability are crucial for practical applications of supercapacitors, however, actually the specific capacitances of transition metal oxides-based electrodes are still far below their theoretical predictions, and their cycling stability cannot satisfy the commercial standard due to intrinsically poor electronic conductivity and volume structural changes during charging/discharging processes. Here, we report the synthesis of hybrid NiO-CuO mesoporous nanowires array with abundant oxygen vacancies which construct a three-dimension (3D) hollow architecture via a facile hydrothermal and subsequent annealing methods. Compared to single-phase NiO or CuO, the increased O-vacancies on the NiO-CuO hybrid nanowires probably arising from a high number of lattice defects can promote its electronic conductivity, as revealed by XPS O1s spectra, EPR characterization and HRTEM images. Besides, the 3D hollow structure together with mesoporous nanowires composed of alternately linked NiO and CuO nanocrystals can relax strain stress either in a hollow 3D structure or along a one-dimensional (1D)-direction nanowire, which not only provides a fast diffusion pathway for electrolyte ions and a high surface area with more active sites, but also helps to maintain the structural integrity during charge/discharge cycles. Therefore, the as-prepared NiO-CuO@Ni foam owns a high areal capacitance of 4.35 F cm-2 and also a very high specific capacitance of 1450.8 F g-1 at a current density of 2 mA cm-2. Further, it can be utilized directly as a binder-free positive electrode, and assembled with a negative electrode based on 3D porous graphene hydrogel (PGH) to construct an asymmetric supercapacitor, which shows a wide potential window of 1.6 V and an outstanding cycling stability of 90.4% capacitance retention after 5 000 charge/discharge cycles.

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Publication details

The article was received on 25 Aug 2018, accepted on 04 Oct 2018 and first published on 06 Oct 2018


Article type: Paper
DOI: 10.1039/C8TA08262F
Citation: J. Mater. Chem. A, 2018, Accepted Manuscript
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    Hybrid NiO-CuO mesoporous nanowires array with abundant oxygen vacancies and hollow structure for high-performance asymmetric supercapacitor

    Z. Fang, S. U. Rehman, M. Sun, Y. Yuan, S. Jin and H. Bi, J. Mater. Chem. A, 2018, Accepted Manuscript , DOI: 10.1039/C8TA08262F

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