Waste leather-derived pumice-like N, S-codoped porous carbon for high-performance supercapacitors

Activated carbon (AC) is a viable material showing extensive potential in several economic sectors including energy applications. We report a facile method for converting waste leather into pumice-like hierarchically porous AC for supercapacitor applications. This study focuses on a novel synthetic strategy for preparing N, S-codoped hierarchical porous AC (A-NSC) with pumice-like morphology from waste leather (WL), which inherently contains, in addition to C, H, and O, elemental N and S and ca. 35% trapped water stabilizing the folded structure of collagen. A two-step carbonization strategy was followed: (i) char was prepared from WL at low pyrolysis temperature, and (ii) it was then pyrolyzed at different elevated temperatures by mixing with excess KOH in an N₂ environment. The hydrophilic surface of N, S-codoped carbon with a high specific surface area (2215 m² g^-1) developed at 800 °C exhibits exceptional electrical charge storage of 1158 F g^-1, along with an energy density of 40 W h kg^-1 in aqueous KOH solution. The developed A-NSCs offered electric double layer-type storage with a negligible decay in consecutive charging-discharging tested for 10 000 cycles. This study opens a new insight into the formation of highly robust, valuable carbon from WL.