A self-template synthesis of hierarchical porous carbon foams based on banana peel for supercapacitor electrodes

Hierarchical porous carbon foams (denoted as HPCFs) is prepared through a novel self-template strategy based on banana peel. Banana peel, which contains natural porous structure formed by biopolymers in cell walls, can absorb ions and phenolic compounds. The carboxylic and hydroxyl groups on the pores' surface will coordinate with zinc ions to form zinc complexes. These zinc complexes which are similar with metal-organic frameworks are used as self-template, and the aminophenol furfural resin polymerized in the pores of complexes is used as the additional carbon source to create hierarchical porous structure during the carbonization process. The resulted HPCFs are composed of macroporous cores with mesoporous and microporous channels. The unique self-supported hierarchical structure possesses a high specific surface area (1650 m(2) g(-1)) and provides a more favorable path for electrolyte penetration and transportation, which give rise to the excellent electrochemical property of HPCFs as an electrode material for supercapacitor. The calculated specific capacitance of HPCFs electrode in 6 mol L-1 KOH is 206 Fg(-1) at a current density of 1 A g(-1), while the specific capacitance still exhibits relative high (182 F g(-1)) at a higher current density of 10 A g(-1) with the retention of 88%. (C) 2012 Elsevier B.V. All rights reserved.