Hollow carbon polyhedra derived from room temperature synthesized iron-based metal-organic frameworks for supercapacitors.

Metal-organic frameworks (MOFs) derived porous carbons are promising electrode materials in electrochemical energy conversion and storage systems. However, the typical synthetic route of MOFs involving high temperature, organic solvent, massive energy consuming, and laboratory-scale production, hinders the realistic applications of MOFs serving as sacrificial templates for porous carbon. Herein, we demonstrate that highly crystalline MIL-100 (Fe) nanoparticles (MIL: Materials of Institute Lavoisier) can be synthesized in large scale with low cost under mild and green conditions. High-temperature pyrolysis of MIL-100(Fe) under argon atmosphere results in hollow carbon polyhedra (HCPs) featuring high degree of graphitization and hierarchical pore structures. The obtained HCPs are excellent electrode materials for electric double-layer capacitors (EDLCs), and show a specific capacitance of 214 F g−1 at current density 50 mA g−1. Moreover, the HCP-based supercapacitors can endure more than 5000 cycles without significant degradation of capacitance. The unique structure of HCPs, including hollow polyhedral shape, hierarchical micro/mesopore structures, and ultrathin layer of highly graphitized carbon shells, endows the superior performance of HCPs based EDLCs with specific capacitance and high rate capability. Image 1 • Room temperature synthesis of MIL-100(Fe) nanocrystals in a low cost and green fashion. • Pyrolysis of MIL-100(Fe) resulted in hollow carbon polyhedra (HCPs). • HCPs show high degree of graphitization and hierarchical pore structures. • HCPs-based SCs exhibit high specific capacitances and excellent cycling stability. [ABSTRACT FROM AUTHOR]