Exocarp-Mesocarp-Endocarp Anatomical Engineering: Oxidation and Activation Tailoring Micromesoporous Alliance...

Biomass-derived porous carbon is an attractive capacitive material due to its controllable porous structure and surface chemistry. However, the microstructural heterogeneity of hierarchical pericarp-derived porous carbon (Pc) has long been overlooked. Herein, the pericarp was physically dissected into the exocarp (Ex), mesocarp (Me), and endocarp (En) by utilizing the structural differences among hierarchical Kigelia africana fruits. Ex-Pc, Me-Pc, and En-Pc are fabricated via an oxidation and activation method. Ex-Pc, Me-Pc, and En-Pc exhibit honeycomb-like, tubular, and ruptured tubular structures, respectively, and present different specific surface areas and pore size distributions. Among them, the specific capacitance of Ex-Pc is 648.0 F g^-1 at a current density of 1 A g^-1, which is much higher than that of Me-Pc (149.1 F g^-1) and En-Pc (191.4 F g^-1). The nanoscale honeycomb-like structure of Ex-Pc makes its micropores more accessible and its surface groups more exposed, which enhances its electrochemical performance. Its specific capacitance maintains as high as 525.0 F g^-1 even at 50 A g^-1. The assembled Ex-Pc-based symmetric supercapacitor achieves high energy density of 16.6 Wh kg^-1 at a power density of 69.4 W kg^-1, and demonstrates a capacitance retention of 95.1% after 43,000 cycles. This work validates the feasibility of enhancing capacitance by exocarp-mesocarp-endocarp anatomical engineering and opens a gap for preparing homogeneous biomass-derived porous carbon microstructures.