MOF derived nitrogen-doped carbon polyhedrons decorated on graphitic carbon nitride sheets with enhanced electrochemical capacitive energy storage performance

Three dimensional carbon materials with hirerarchically porous structure could exhibit superior energy storage performance than two dimensional stacked carbon nanosheet materials. In this work, we prepared a novel ZIF-8-derived nitrogen doped carbon nanoparticles/graphitic carbon nitride composite electrode material with high electrochemical energy storage performances, including high specific capacitances (495 F g−1 at 0.1 A g−1 and 188 F g−1 at 20 A g−1) and a stable cycling durability with no capacitance declination after 5000 charge-discharge cycles in three-electrode system. When assembled as electrode materials in symmetrical two-electrode system, the as-prepared composite electrode material could exhibit high specific capacitances of 349.7 F g−1 at 0.5 A g−1 and 261.2 F g−1 at 5 A g−1. Accordingly, a high energy density of 11.89 Wh/kg can be achieved at the power density of 247.40 W kg−1. The improvement stems from its hierarchically porous structure with dominant pore sizes at 3 nm and among 4–40 nm, as well as high exposed pyridinic nitrogen (8.58 at%) and pyrrolic nitrogen (3.59 at%) active sites caused by the insertion of ZIF-8-derived nitrogen doped carbon nanoparticles between g-CN layers. This study has provided a new idea on the design of graphitic carbon nitride nanostructures with improved doping level and hiearchically porous structure. Since the insertion of MOF derived nitrogen-doped carbon polyhedrons between the g-CN layers could effectively improve the hierarchically porous structure, the ion transportation and the faradic reactions in it during the charge-discharge process are favored and thus afford it high electrochemical capacitive properties and high cycling stability. [Display omitted]