CO2-activated porous carbon aerogel from cucumber as an electrode material for high-performance supercapacitors in energy storage applications

Biomass-based carbon aerogel materials possessing their porous structures and physicochemical properties have attracted considerable interest for energy storage applications in the context of sustainable development. Herein, activated cucumber-derived carbon aerogel (A-CCA) materials were prepared through a facile synthesis route involving hydrothermal treatment, freeze-drying, and pyrolysis with the CO 2 activation. Controlling the pyrolysis carbonization temperatures could improve the microstructure and electrochemical properties of A-CCA materials. As a result, these prepared materials exhibited intriguing characteristics with low density (0.122 – 0.006 g/cm 3 ), high porosity (> 98%), abundance of microporous and mesoporous structures along with edge-plane-like defective sites. The electrochemical capabilities of the obtained materials were studied in both three- and two-electrode systems. Consequently, the A-CCA materials obtained illustrated an outstanding electrochemical performance with an electric double-layer capacitance behavior and an excellent specific capacitance of 217.13 and 74.88 F/g at a current density of 0.5 A/g in three- and two-electrode systems, respectively. The achieved outcomes promoted a potential and sustainable pathway for utilizing a low-cost industrial crop like cucumber for energy storage technologies through green synthesis without toxicity chemical approaches.