Ionic Liquid Templated Porous Boron-Doped Graphitic Carbon Nitride Nanosheet Electrode for High-Performance Supercapacitor

Two dimensional heteroatoms-doped graphitic carbon electrode materials could exhibit better capacitive properties than undoped carbon materials. However, since the configuration and the content of the heteroatoms as well as their porous structure are difficult to control, the improvement of their energy storage performance is limited. Here, we report a hierarchically porous boron-doped graphitic carbon nitride nanosheet electrode material with high electrochemical energy storage performances, including high specific capacitances at a fast, carbon-like speed (620.0 F g−1 at 0.1 A g−1 and 312.0 F g−1 at 20 A g−1), a high energy density of 86.1 Wh kg−1 and a stable cycling durability with no capacitance declination after 2500 charge-discharge cycles. The improvement stems from the hierarchically porous structure with dominant pore sizes among 1-3 nm, increased pyrrolic nitrogen (11.12 at%) and boron (8.21 at%) active sites due to the addition of ionic liquid. This study has provided a new idea on improving the doping level and porous structure of the electrode material by using ionic liquid as both the heteroatoms source and pore template.

Since ionic liquid template could effectively improve the hierarchically porous structure as well as the contents of pyrrolic nitrogen and boron atoms in the as-prepared graphitic carbon nitride, 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.226