Carbon materials with hierarchical porosity: Effect of template removal strategy and study on their electrochemical properties

The porosity of carbon materials can be tuned by controlling the template removal strategies in silica/carbon composites. In this study, chitosan was used as precursor for carbon, and SiO2 nanoparticles were selected as the template for mesopores. The spray drying technique was adopted for the fabrication of silica/chitosan microspheres. Porous carbon with hierarchical macro/meso/micro pores was obtained through a facile one-pot high temperature treatment, in which the pyrolysis of the chitosan precursor, removal of the silica template, and introduction of macropores coordinatively occur using PTFE (polytetrafluoroethylene) binder as a silica etchant and also as a macropore director. This approach not only simplifies the fabrication processes but also yields regular honeycomb-like carbon with macro/meso/micro-sized hierarchical pore structure with high specific surface areas up to 1011 m2 g−1. A supercapacitor assembled with porous carbon as the electrode exhibited a high specific capacitance of 250.5 F g−1 at a current density of 0.5 A g−1 using 6 mol L−1 KOH as the electrolyte in a three-electrode system. The supercapacitor also delivered excellent cycling stability with an enhancement of capacity up to 107% over 5000 cycles at a high current density of 10 A g−1.