Direct growth of multilayered graphene nanofibers by chemical vapour deposition and their binder-free electrodes for symmetric supercapacitor devices

Abstract

This work reports the direct growth of graphene nanofibers (GNFs) on metallic foils, namely nickel (Ni) and stainless steel (SS) and their use of direct device assembling of symmetric supercapacitor electrodes applications. GNFs were directly grown on Ni and SS through a chemical vapour deposition (CVD) technique, employing acetylene as a carbon source with 700 °C at 30 min. GNFs were grown on metallic foils with and without coating of NiNO3 catalytic layers by drop-casting method. As prepared GNFs on Ni and SS metallic foils were direct studied employing scanning electron microscope (SEM). The morphological images explored bending and curved nature forest growth of GNFs in cross-section micro-structure well growth of catalytic supports. The high-resolution morphological transmission electron microscope (TEM) results were explored highly branched multi-layers of graphene walls (d-spacing 0.34–0.48 nm) with GNFs size ranges of 100–50 nm. The micro-Raman spectrum results showed the IG/ID – 1.29 and also observed 2D-band at 2679.82 cm−1 for graphene layers for Ni-NiNO3-GNFs. The direct growth GNFs (Ni-NiNO3-GNFs) electrode was further investigated for the electrochemical supercapacitor device performance. The cyclic voltammetry (CV) results showed an ideal capacitive window (0.01–1.5 V) with impedance spectroscopy of 27.57 Ω Rct values. The direct assembled binder-free symmetric device is a new approach for supercapacitor applications with charge-discharge that Ni-NiNO3-GNFs sample has 24.66 F/g capacitance at 0.5 F/g. GNFs are in good contact with Ni and facilitate low Rct examined in impedance study. These overall results indicated well growth Ni-catalytic supports of bulk growth of graphene-like fibrous forest growth nanostructures on metallic foils. The prepared electrochemical energy storage symmetric device explored a good charge-discharge cycle as suitable for future high direct electrode applications for supercapacitor devices employing CVD techniques.