Novel MgO/few-layer graphene-filled polyaniline ternary nanocomposite as efficient electrode material in aqueous supercapacitors

Abstract

MgO/few-layer graphene (FLG) nanocomposite is proven as an excellent electrode in aqueous supercapacitors (AS). The synergy between the pseudo-capacitive MgO and the double-layer charging nature of FLG that enhances the supercapacitors' specific capacitance (SC) was successfully tested. The SC could be further enhanced by combining MgO/FLG with a third component, such as a conducting polymer (with a Faradaic type of charge storage capability). Herein, such an attempt has been made. MgO/FLG was uniformly filled in polyaniline (PANI) by using a simple in situ polymerization method. X-ray diffraction, electron microscopy, and Raman and Fourier transform infrared spectroscopic analyses clearly showed the formation of a ternary nanocomposite constituted by MgO, FLG and PANI. As anticipated, the ternary nanocomposite (MgO/FLG-filled PANI (MFP)) exhibited an enhanced SC (compared to MgO/FLG) when tested as electrode material in AS. The MFP composite was evaluated for SC using a 3-electrode system. MFP composite exhibited a maximum SC of 347 F g⁻¹ when tested at a scan rate of 5 mV s⁻¹ using 1 M aqueous H₂SO₄ as the electrolyte. The electrode material assumable with symmetric capacitance achieved a maximum capacitance of 396 F g⁻¹ at a current density of 1 A g⁻¹ and showed a capacitance retention of 81%. In contrast, MgO/FLG exhibited much lower values under similar testing conditions.