LAUSR

Abstract Biomass is receiving considerable attention because of its significant advantages as a sustainable and renewable material. Willow catkins, which have a single-walled microtubular structure are used as both a template and a precursor for synthesizing porous graphitic carbon microtubes (PGCMT) induced by the simultaneous activation–graphitization of K 4 Fe(CN) 6 . In addition to providing low-resistant pathways and short ion diffusion channels, as-obtained PGCMT with tubular structure also serves as an ideal platform for anchoring MnO 2 . The PGCMT/MnO 2 composite electrode obtained by MnO 2 electrodeposition expressed excellent electrochemical performance, including a significantly enhanced specific capacitance (550.8 F g −1 for the mass of MnO 2 at a current density of 2 A g −1 ), a high capacitance retention of 61.8% even at a high current density of 50 A g −1 , and an excellent cycling stability of 89.6% capability retention after 5000 cycles. These findings offer a simple and environmentally friendly strategy for preparing advanced energy materials by utilizing the unique structure of biomass waste from nature.