Two dimensional layered bismuthene nanosheets with ultra-fast charge transfer kinetics as a superior electrode material for high performance asymmetric supercapacitor

Abstract

Two dimensional (2D) materials with unique quantum chemistry, tunable interlayer bandgap, and active functional groups extensively enhance the electrochemical behavior in electrochemical energy storage devices. Herein, we synthesize the bismuthene nanosheets from bulk metallic bismuth powder using the standard liquid phase exfoliation technique. As a result, the X-ray diffraction (XRD) spectrum reveals the rhombohedral crystal structure of the bismuthene nanosheets and their active functional groups have been identified by Fourier transform infrared (FTIR) analysis. Likewise, the high resolution transmission electron (HR-TEM) microscopy reveals the morphology and surface nature of the 2D bismuthene nanosheets with high transparency with the interplanar lattice spacing of 0.328 nm. Moreover, the atomic force microscopy (AFM) shows the stacking of 11–12 layer nanosheets with an average sheet thickness of about 4.7 nm. Cyclic Voltammetry (CV) analysis of the delaminated bismuthene nanosheets provides the gravimetric capacity of 350 mAh/g at 10 mV/s. Furthermore, Trasatti and Dunn's approach demonstrates the charge storage process and the obtained total, outer, and inner capacity of bismuthene nanosheets are 724.6, 34.7, and 689.6 mAh/g respectively with the capacitive and diffusive contributions are 95.2% and 4.8% correspondingly. Moreover, the asymmetric supercapacitor (ASC) based on bismuthene and activated carbon (AC) delivers the maximum specific capacity of 87.3 mAh/g at 1 A/g, together with the energy density of 27.23 Wh/kg corresponding to the power density of 312.5 W/kg.