Preparation and Multifunctional Applications of Nitrogen-doped Porous Carbon Materials

Porous carbon materials (PCMs) have drawn wide attention in gas adsorption and energy storage due to their large specific surface areas, physical and chemical stability and structural diversity. Doping heteroatoms such as nitrogen species has been considered as a reasonable method to enhance the application performance of PCMs by improving the interactions between PCMs and adsorbates. However, heteroatom-doped PCMs prepared with traditional methods such as chemical activation have disadvantages of broad pore size distribution and difficulty in accurately locating heteroatoms on the skeleton of PCMs, thus limiting their applications in gas adsorption and energy storage. Conjugated microporous polymers (CMPs) with excellent structural controllability and permanent microporous properties are considered to be a new choice for the preparation of PCMs. In this work, two nitrogen-doped PCMs with different structural units were prepared by using CMPs as the precursors. First of all, two CMPs (TNCMP1, TNCMP2) were synthesized by Pd-catalyzed Suzuki coupling reaction. Then the CMPs were pyrolyzed at 700 degrees C to give two PCMs (C-TNCMP1, C-TNCMP2). The effects of carbonization and planarity adjustment on carbon dioxide (CO2) adsorption and supercapacitor performance of the PCMs were studied. Compared with their precursors, the obtained PCMs exhibit narrower pore size distribution and higher microporosity up to 93%. Thus, both of the PCMs show higher CO2 adsorption ability than their precursors, among which the CO2 adsorption capability of C-TNCMP1 is up to 3.19 mmol/g. Compared with C-TNCMP1, C-TNCMP2 with better structural planarity has larger graphite nitrogen content of 57.39 at% and higher conductivity of 3.89 x 10(-5) S/m, thus showing better supercapacitor performance. C-TNCMP2 exhibits a decent specific capacitance of 219 F/g at the current density of 0.1 A/g and a good rate capability at high current density. This work could provide a rational principle for the preparation of high performance porous carbon materials for the applications of gas adsorption and energy storage.