<p>Emerging carbonized polymer dots (CPDs) from natural aromatic-like lignin biopolymer have ignited the renaissance of sustainable nanoscale biomass valorization but are hindered by structural instability and functionality barriers. Herein, we report an interfacial heterostructure engineering that immobilizes lignin-based dual-emissive CPDs onto Fe, Co layered double hydroxides (LDHs), with the function of a recyclable electrode. The CPDs deliver a stable metal-ion binding behavior <i>via</i> rapid light-quenching with a low limit-of-detection, which are fixed into FeCo-LDH to improve the electrical conductivity, available reactive site, structural stability, and charge storage. The reconstructed FeCo-LDH@CPDs electrode outputs an ultrahigh specific capacitance of 1842.0&#xa0;F g^− 1 at 1 A g^− 1. When assembled into a symmetrical supercapacitor (SSCs), it also achieves a superior energy density of 33.79 Wh kg^− 1 at 375&#xa0;W kg^− 1, excellent rate performance and long-term cycling lifespan (100% retention after 10,000 cycles even at 20&#xa0;A g^− 1). To validate a closed-loop upcycling of end-of-life electrode, we demonstrate that the recycled FeCo-LDH@CPDs offer a robust Fenton-like catalytic reactivity to fulfill a rapid, reversible and ionic anti-interfering antibiotics elimination. We confirm the participation of singlet oxygen ¹O₂-dominated reactive oxygen species and persistent electron shuttling in tetracycline oxidation. Towards achieving renewable resource technologies, our work sheds an insight on designing high-performance CPDs-hybrid electrode from biomass, ranging from lignin to collagen and/or leather, with the reusable catalytic capabilities to exert a bifunctional energy-water footprint.</p> Graphical Abstract <p></p>