<i>In situ</i> nitrogen-doped porous carbon from waste baby diapers as a high-performance supercapacitor electrode material

This study presents a method for the synthesis of nitrogen-doped porous carbon (NAPC) from nitrogen-rich superabsorbent material (SAP) found in waste baby diapers for application as an electrode material for high-performance supercapacitors. Through rapid pyrolysis and KOH activation, the resulting NAPC material exhibited a high specific surface area and abundant microporous structure, which promoted efficient ion transport and energy storage. Electrochemical testing demonstrated that the NAPC-650-4 sample achieved a specific capacitance of 353 F g^-1 at a current density of 1 A g^-1 in a 6 M KOH electrolyte, with a capacitance retention rate of 87.65% after 10 000 cycles. This finding indicates the material's excellent rate capability and cycle stability. Furthermore, the symmetric supercapacitor assembled from NAPC-650-4 delivered an energy density of 7.22 Wh kg^-1 at a power density of 125 W kg^-1, which showed its potential for high-power applications. This research not only provides a feasible green solution for recycling waste diapers but also a new approach for the development of high-performance electrode materials.