Bifunctional Energy‐Environment Engineering of Biomass Valorization to Enable Sustainable Zinc‐Ion Hybrid Capacitor and Fenton‐Like Catalytic Reaction

ABSTRACT The multifunctional waste‐free valorization of biomass is urgently needed to shape the carbon‐neutral future of sustainable energy storage and water purification, yet it is still suffering from the dilemma of its complex structures and molecular heterogeneities. This work integrates alkaline sulfite fractionation with deep eutectic solvent neutralization to achieve a stepwise conversion of bamboo into bifunctional energy‐environment materials. As an electrode of zinc‐ion hybrid capacitors, the hierarchically‐porous lignin‐based cathode with defect‐rich architecture delivers an exceptional energy density of 136.1 Wh kg ⁻¹ at 900 W kg ⁻¹ with outstanding rate capability and long‐term cycling stability (84.4% over 10 000 cycles), owing to the enhanced affinity of Zn ²⁺ by Fe, N, and S co‐doping. Beyond that, the carbonized pulp‐fiber catalysts featuring alkali‐etched mass‐transfer channels and cobalt‐incorporated active‐centers demonstrate efficient Fenton‐like water remediation, including superior antibiotic adsorption and percarbonate activation (over 85% removal of tetracycline, oxytetracycline, and chloroquine‐phosphate at 100 mg L ⁻¹ ), robust anions anti‐interference, and durability. Mechanistic and theoretical investigations reveal that the synergistic degradation involves surface‐binding radical generation, ¹ O ₂ , interfacial electron transfer, and adsorption‐intensified oxidation, varying with the pollutant physicochemical properties of half‐wave potential and molecular orbital energy. This work expands a practical closed‐loop lignocellulose platform of bringing advanced functions into biomass‐energy‐water nexus fields.