Sawdust-derived carbon aerogel/Co₃O₄ nanocomposite for high-performance supercapacitor electrodes

Lignocellulose based Carbon Aerogels were synthesized from sawdust via a facile microwave assisted freeze thaw technique. Initially, sawdust was gelled using a microwave treatment and a freeze-thaw method in a solution of sodium hydroxide and urea. The ambient-dried gel was then subsequently carbonized for two hours at 500 °C in a muffle furnace. Furthermore, precipitation reaction of cobalt nitrate and sodium hydroxide at 70 °C followed by calcination at 300 °C result in cobalt oxide (Co 3 O 4 ). FTIR, XRD, TGA, BET, and SEM/EDX, and XPS were used to characterize and validate the synthesis of carbon aerogel and cobalt oxide in both their pristine and composite forms. The biomass carbon aerogel and cobalt oxide composite material is rich in (O-H) and (Co-O) functional groups with stretching vibrations, thermally stable, and crystalline structure. The BET analysis results show that the composite material is very porous with a specific surface area of 1287 m 2 /g, pore volume of 0.5865 cc/g, and pore diameter of 12.98 nm. Cyclic voltammograms, Galvano charge discharges, and Electrochemical impedance were used to assess the supercapacitor performance of the materials. The carbon aerogel/cobalt oxide composite material showed a specific capacitance of 421 F/g at 1 Ag −1 and energy density of 7.2 Wh/kg and 182.5 W/kg power density in 6 M KOH electrolyte.