2D g-C3N4 decorated with 1D Bi2S3 nanocomposite as a high performance electrode material for asymmetric supercapacitors

Abstract

Energy accumulation and storage is one of the most vital areas and necessities in today's world. The supercapacitor is seen as one of the most promising energy storage devices for upcoming generations. In this work, two dimensional (2D) g-C3N4 nanosheets decorated with one dimensional (1D) Bi2S3 nanorods by using rapid and simple hydrothermal method. The structure, functional groups, morphology and elemental analyses of synthesized materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX). In electrochemical study, pure Bi2S3 nanorods, g-C3N4 nanosheets, and Bi2S3/g-C3N4 composite electrode material were tested. In compared to pure samples, the Bi2S3/g-C3N4 composite demonstrated high specific capacitance of 631 Fg-1 at a current density of 1 Ag-1, as well as outstanding cyclic stability of 94% retained over 5000 cycles at a maximum current density in aqueous Na2SO4 electrolyte. The Bi2S3/g-C3N4 composite electrode exhibits superior electrochemical performance owing to the synergetic effect of Bi2S3 nanorods and g-C3N4 nanosheets. Also, the Bi2S3/g-C3N4 composite has been suggested as an excellent electrode material for supercapacitor applications. The fabricated Asymmetric supercapacitor device (ASC) has high specific capacitance of 80 F g−1 with 89% capacitance retention after 5000 cycle at current density of 10 A g−1. The ASC device achieved maximum energy density of 44.4 Wh kg−1 at 999 W kg−1 in operating potential range 0–2 V. Also ASC device fabricated for practical application and tested by charging 30 S and attained a self-discharging time of 3 min.