Preparation and Capacitive Performance of Nitrogen‐Doped Natural Integrated Carbon Sheets Derived From Waste Leather

Waste leather (pig/cattle/sheep) was converted into nitrogen‐doped carbon sheets via high‐temperature carbonization and CO 2 activation. Characterization via thermogravimetric analysis, a scanning electron microscopy, nitrogen adsorption–desorption, and an X‐ray photoelectron spectroscopy revealed nitrogen‐doped carbon sheets feature a 748 m 2 g −1 surface area, hierarchical micro‐mesopores, and 4.55 at% nitrogen. Electrochemical tests in 6 M KOH showed SL‐CAC electrodes exhibit 197.6 F g −1 capacitance (0.3 A g −1 ), 61.3% rate retention (0.3–5 A g −1 ), and 98.36% stability over 10 000 cycles. Performance gains stem from enhanced ion transport via porous structure, nitrogen‐induced pseudocapacitance, and reduced resistance from integrated design. This work enables sustainable leather waste recycling and advanced supercapacitor electrode development.