Electron Transport Shuttle Mechanism via Fe-N-C Bond Derived from Conjugated Microporous Polymer for Supercapacitor

Abstract

A new innovative electrode material (Fe-P800) consisting of a metal complex anchored on carbon via the utilization of iron-porphyrin conjugated microporous polymer (Fe-CMP) was prepared after pyrolyzing at 800 degrees C. The usage of the polymer with iron-porphyrin repeating units maximized the possible formation of Fe-N-x coordination within the bulk of the sample while the thermal treatment rendered the carbon framework to form a distinct arrangement between metal, nitrogen and carbon with a high surface area of 450 m(2) g(-1). The formation of the M-N-C bond, confirmed through XPS analysis, established a direct interaction between metal and carbon material. Thus, an indisputable synergistic effect was observed leading to a high capacitance of 182 F g(-1) at a current density of 1 A g(-1) despite its low metal loading of similar to 1%. It also exhibited a highly robust cycling stability of similar to 100% capacitance retention even after 5000 cycles (10 A g(-1)). In this study, a new mechanism was proposed wherein the metal (iron) center features an electron access point via its highly reversible redox reactivity, providing a shuttle effect for charge transfer to the conductive graphitic carbon matrix.