Oxygen-Functionalized Hierarchical Porous Carbons from Beech Wood: Exceptional Electrochemical Performance for Supercapacitors

This study presents an approach to fabricating oxygen-rich porous carbon materials from preoxidized beech wood using (NH4)2CO3 as a multifunctional agent. The preoxidation process introduces oxygen-containing functional groups, enhancing the structural stability during carbonization. The thermal decomposition of (NH4)2CO3 generates NH3, CO2, and H2O, where NH3 reacts with the oxygen groups to incorporate nitrogen into the carbon lattice, while CO2 and H2O etch pores, resulting in a significant increase in specific surface area from 123.6 to 1134.3 m2/g. The resulting carbon material exhibits a mass-specific capacitance of 176.7 F/g and an area-specific capacitance of 12.88 F/cm2 at a rate of 5 mA/cm2. Symmetrical supercapacitors (SSCs) fabricated from this material demonstrate a high specific capacitance of 127.44 F/g and an areal specific capacitance of 12.74 F/cm2 at 1 mA/cm2, with 101.4% capacitance retention after 10,000 cycles at 10 mA/cm2. Compared with other electrode materials, these SSCs exhibit superior energy density and capacitive performance. This environmentally friendly method offers promising prospects for the development of high-performance supercapacitor electrode materials.