Preparation and characterization of BiOBr/g-C3N4 and BiOCl/g-C3N4 electrode materials for high-performance asymmetric (BiOBr/g-C3N4||g-C3N4) and symmetric (BiOBr/g-C3N4||BiOBr/g-C3N4) supercapattery devices

The drastic depletion of fossil fuels and ever increasing environmental pollution are the two key factors to search for alternative renewable energy resources. Nowadays, hybrid Electrochemical Energy Storage device (EES) known as supercapattery is considered as the prominent green energy source, because of having the merits of both supercapacitors and batteries. In the present work, two different hybrid electrode materials namely Bismuth oxybromide (BiOBr)/graphitic carbon nitride (g-C3N4) [BBGN] and Bismuth oxychloride (BiOCl)/graphitic carbon nitride (g-C3N4) [BCGN] were synthesized using a facile precipitation method where BiOBr (BB)/BiOCl (BC) was decorated at the surface of g-C3N4 (GCN). The prepared hybrid electrodes BBGN and BCGN exhibit high specific capacity of 1248.84 C/g and 1022.67 C/g at a current density of 1 A/g, compared to BB, BC and GCN electrodes. The sheet like morphology of BBGN and BCGN promotes fast ion transfer and thereby enhances the power density and energy density. The fabricated BiOBr/g-C3N4||BiOBr/g-C3N4 symmetric supercapattery (SSC) device delivered an excellent energy density of 22.5 Wh/kg than BiOBr/g-C3N4||g-C3N4 asymmetric supercapattery (ASC) device (14.76 Wh/kg). The performance of SSC device was demonstrated using a 2 V red light emitting diode (LED) and it could able to power for 5 min 35 s. Hence, these results authenticate that the BiOBr/g-C3N4 nanocomposite may serve as a promising electrode material for supercapattery applications in the realm of renewable energy. [Display omitted] •Two hybrid electrodes BiOBr/g-C3N4 (BBGN) and (BiOCl/g-C3N4) (BCGN) were synthesized.•Battery behaviour of BiOBr/BiOCl and capacitive behaviour of GCN were noticed.•BBGN||BBGN symmetric supercapattery shows energy density of 22.5 Wh/kg and power density of 3.0 kW/kg.•BBGN||BBGN device could power a commercial red LED for 335 s than BBGN||g-C3N4 device.