Adsorption of Toxic Cd(II) on an Antibacterial Biopolymeric Gel toward Fabrication of a Gel Electrolyte-Based Supercapacitor Device

Both water and energy are extremely crucial in the contemporary world. Hence, cutting-edge technologies to reduce water pollution and to develop sustainable energy storage appliances are two major key areas in recent times. In this context, cadmium pollution is a severe threat to mankind. Herein, a cross-linked β-cyclodextrin (β-CD) hydrogel has been synthesized via grafting and cross-linking of poly(N-isopropylacrylamide) and poly(2-acrylamido-2-methylpropane) sulfonic acid on β-CD. The hydrogel is biocompatible, antibacterial, and biodegradable in nature and exhibits excellent pH and thermoresponsive Cd2+ adsorption efficiency from wastewater. Moreover, this Cd2+-adsorbed hydrogel has been found to be efficient as a gel electrolyte in a high-performance asymmetric supercapacitor for energy storage application. The Cd2+-adsorbed hydrogel, when used to fabricate a supercapacitor device as a gel electrolyte, demonstrates a higher specific capacitance and a higher energy density of 203.84 F/g and 54.30 Wh/kg, respectively. The developed device is fairly stable even after 5000 cycles and retains 77% charge. The gel-based supercapacitor device is also capable of illuminating red and green light-emitting diodes.