doi:10.1016/j.biombioe.2025.107633engAntorán, DanielAlvira, DaríoSebastián, VíctorManyà, Joan J.Scalable synthesis of heteroatom-doped carbons from waste hemp hurd with enhanced sodium-ion and potassium-ion storage capabilitiesART-2025-142567In this study, we applied an easily scalable two-step process comprising hydrothermal pretreatment with simultaneous mild heteroatom doping (N, N-S, and N-P) followed by carbonization at 800 °C to synthesize hard carbons (HCs) from waste hemp hurd for Na-ion and K-ion storage. The proposed synthesis pathway represents a viable alternative to the more energy-intensive, environmentally harmful, and/or challenging to scale up processes reported in the literature. The resulting carbons, particularly the dual NP-doped and single N-doped varieties, demonstrated improved electrochemical performance in terms of specific capacity (indicating more reversible ion storage sites) and rate capability (reflecting faster ion transport kinetics). These enhancements can be attributed to structural and surface chemistry modifications introduced during hydrothermal pretreatment. For Na-ion storage, the N-doped HC achieved a specific capacity of 293.6 mAh g−1 at 0.1 A g−1 (and 125 mAh g−1 at 1 A g−1) with an initial coulombic efficiency (ICE) of 73.5 % using an ester-based electrolyte. The same material showed an enhanced rate capability when an ether-based electrolyte was employed, achieving 155 mAh g−1 at 1 A g−1. For K-ion half-cells, the dual N-P-doped HC exhibited the best performance at low current rates, delivering a specific capacity of 260 mAh g−1 at 0.1 A g−1 in ester-based electrolytes. However, the N-doped HC showed the best rate capability at 2 A g−1 (57 mAh g−1), which is a reasonable value given the lack of mesopores in produced HCs.2025http://zaguan.unizar.es/record/15045310.1016/j.biombioe.2025.107633http://zaguan.unizar.es/record/150453oai:zaguan.unizar.es:150453info:eu-repo/grantAgreement/ES/DGA/T22-23Rinfo:eu-repo/grantAgreement/ES/MICINN/PDC2022-133866-I00info:eu-repo/grantAgreement/ES/MICINN/PID2021-127847OB-I00info:eu-repo/grantAgreement/ES/MCINN/PID2022-137218OB-I00BIOMASS & BIOENERGY 194 (2025), 107633by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess