Decoration of nitrogen-doped reduced graphene oxide with cobalt tungstate nanoparticles for use in high-performance supercapacitors

• Published in: Applied surface science 2017-11, Vol.423, p.1025-1034
• Main Authors: Naderi, Hamid Reza, Sobhani-Nasab, Ali, Rahimi-Nasrabadi, Mehdi, Ganjali, Mohammad Reza
• Format: Article
• Language: English
• Subjects: CoWO4 nanoparticles; Electrochemical properties; N-Doped graphene; Nanocomposite materials; Supercapacitor
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2017.06.239

[Display omitted] •CoWO4 are anchored on the surface of nitrogen-doped reduced graphene oxide (NRGO).•CoWO4/NRGO nanocomposite show high capacitance, good rate and cycling performance.•The nanocomposite electrode exhibits specific capacitance of 597Fg−1 in 5mVs−1.•The CCV reveals 97.1% retention of initial capacitance for CoWO4/NRGO after 4000 cycles. A composite of cobalt tungstate nanoparticles coated on nitrogen-doped reduced graphene oxide (CoWO4/NRGO) was prepared through an in situ sonochemical approach. The composite was next evaluated as an electrode material for use supercapacitors electrodes. The characterization of the various CoWO4/NRGO nanocomposite samples was carried out through field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method and Raman spectroscopy. Complementary studies were also performed through cyclic voltammetry (CV), galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), and continues cyclic voltammetry (CCV). The electrochemical evaluations were carried out in a 2M H2SO4 solution as the electrolyte. The electrochemical evaluations on the nano-composite samples indicated that CoWO4/NRGO-based electrodes reveal enhanced supercapacitive characteristics (i.e. a high specific capacitance (SC) of 597Fg−1 at a scan rate of 5mVs−1, an energy density (ED) value of 67.9Whkg−1, and high rate capability). CCV studies indicated that CoWO4/NRGO-based electrodes keep 97.1% of their original capacitance after 4000 cycles. The results led to the conclusion that CoWO4/NRGO effectively merge the merits of CoWO4 and CoWO4/RGO in one new nanocomposite material.