Mild activation strategy for porous carbon materials: using Sodium bicarbonate and Potassium bicarbonate as activators for high-performance supercapacitors

<title>Abstract</title> <p> Biomass-derived porous carbons activated by green agents have emerged as a promising candidate for high-performance energy storage devices, addressing the dual challenges of fossil energy depletion and environmental pollution. Herein, we reported a facile, scalable, and eco-friendly strategy to fabricate hierarchical porous carbons (HPCs) using discarded badminton feathers as the carbon precursor and water-soluble NaHCO ₃ /KHCO ₃ as green co-activators. Benefiting from the synergistic activation effect of NaHCO ₃ and KHCO ₃ , the optimized carbon sample (CC-C/Na/K-1:2:1) exhibited a high specific surface area (S _BET ) of 688.2 m ² g ^− 1 . Moreover, the inherent heteroatoms (N, O, P, S) in the feather biomass are effectively retained in the carbon framework, with doping contents of 7.33 at.%, 11.68 at.%, 0.19 at.% and 0.32 at.%, respectively. When evaluated as a supercapacitor electrode in a 6 M KOH three-electrode system, the CC-C/Na/K-1:2:1 sample delivered a superior specific capacitance of 277 F g ^− 1 at 1 A g ^− 1 . For practical device applications, symmetrical coin-cell supercapacitors assembled with CC-C/Na/K-1:2:1 electrodes achieved a maximum energy density of 20.8 Wh kg ^− 1 at 500 W kg ^− 1 1 M Na ₂ SO ₄ electrolyte. This work not only realizes the high-value conversion of low-cost feather waste but also provides a green and sustainable approach for the synthesis of HPCs. </p>