Joule Heating-Driven sp2-C Domains Modulation in Biomass Carbon for High-Performance Bifunctional Oxygen Electrocatalysis

Natural biomass-derived carbon material is one promising alternative to traditional graphene-based catalyst for oxygen electrocatalysis. However, their electrocatalytic performance were constrained by the limited modulating strategy. Herein, using N-doped commercial coconut shell-derived activated carbon (AC) as catalyst model, the controllably enhanced sp²-C domains, through an flash Joule heating process, effectively improve the edge defect density and overall graphitization degree of AC catalyst, which tunes the electronic structure of N configurations and accelerates electron transfer, leading to excellent oxygen reduction reaction performance (half-wave potential of 0.884 V_RHE, equivalent to commercial 20% Pt/C, with a higher kinetic current density of 5.88 mA cm^-2) and oxygen evolution reaction activity (overpotential of 295 mV at 10 mA cm²). In a Zn-air battery, the catalyst shows outstanding cycle stability (over 1200 h) and a peak power density of 121 mW cm^-2, surpassing commercial Pt/C and RuO₂ catalysts. Density functional theory simulation reveals that the enhanced catalytic activity arises from the axial regulation of local sp²-C domains. This work establishes a robust strategy for sp²-C domain modulation, offering broad applicability in natural biomass-based carbon catalysts for electrocatalysis.