Pea peel waste-derived hierarchical porous carbon for dual applications in water purification and aqueous zinc-ion capacitors

Waste valorization towards the application of energy and environmental remediation is an excellent and effective approach for the sustainable development. In this work, pea peels ( Pisum sativum ), an abundant agricultural residue, were converted into porous activated carbon and used for dual applications in wastewater remediation and aqueous zinc-ion capacitors (AZICs), without the use of harmful chemicals or metal/metal oxide-based adsorbents. The pea peel-derived activated carbon (PPAC-800), synthesized via controlled thermal annealing at an optimized temperature, exhibited excellent adsorption performance towards methylene blue dye, achieving a maximum Langmuir adsorption capacity of 440.5 mg g −1 with a removal efficiency of 99%. Furthermore, the same biomass-derived activated carbon was employed as a cathode material in aqueous zinc-ion capacitors, delivering a specific capacitance of 152 F g −1 and an energy density of 54 Wh kg −1 at a current density of 1 A g −1 . The hierarchical porous architecture and heteroatom-rich surface promote rapid ion transport and efficient charge storage, resulting in enhanced electrochemical performance and good cycling stability. This study demonstrates a sustainable waste-to-value approach for converting abundant agricultural waste into multifunctional carbon materials for environmental remediation and energy storage applications.