High-Volumetric Supercapacitor Performance of Ordered Mesoporous Carbon Electrodes Enabled by the Faradaic-Active Nitrogen Doping and Decrease of Microporosity

Introducing electroactive nitrogen functionalities and decreasing microporosity are favorable for increasing the bulk density and thus beneficial for enhancing the volumetric performance of supercapacitors (SCs) that are based on ordered mesoporous carbon (OMC). Herein, a universal method of graphitic carbon nitride (g-C3N4)-mediated self-assembly of phenolic resin and F127 surfactant was developed to prepare nitrogen-doped ordered mesoporous carbon (NOMC), in which g-C3N4 mainly serves as the nitrogen source to functionalize the surface of the mesoporous carbon. Doped with electroactive functionalities, the NOMC shows low microporosity and highly exposed external surfaces. The nitrogen mainly exists as pyridinic N (N-6), pyrrolic N (N-5), and pyridinic nitrogen oxide (N-O), showing a high content of up to 24.1 atom %. With the maintenance of ordered mesoporosity, ordered channels are observed. Benefited from the large amount of the accessible electrochemically active nitrogen species, volumetric SC performance superior to those of some recently reported nanocarbon electrodes could be achieved, including a large capacitance of 420 F/cm3 (382 F/g equivalent) at 0.5 A/g and maintaining 258 F/cm3 at 20 A/g, an excellent rate capability of 61.4% (vs 27.1% of OMC973), and an excellent energy density of 29.8 W h/L at 990 W/L, implying promising candidacy for portable energy storage devices. Moreover, the fabricated carbon material with ordered mesoporosity and rich nitrogen functionalities may find wide application in areas such as sorption and catalysis.