Band gap-Tunable Porous Borocarbonitride Nanosheets for High Energy-Density Supercapacitors.

Band gap-tunable porous borocarbonitride (BCN) nanosheets were successfully fabricated with cheap and readily available precursors by annealing and exfoliating. The band gap of the as-prepared BCN materials ranges from 5.5 to 1.0 eV; these samples exhibit beneficial structural features suitable for the application in supercapacitors. Especially, the BCN material with a band gap of 1.0 eV exhibits a great specific surface area (600.9 m2 g-1 ), massive active sites, and excellent conductivity (10.8 S m-1 ). In addition, this example displays great specific capacitance (464.5 F g-1 ), excellent cycle stability (98.5% performance retention after 10 000 cycles), and ultrahigh energy density (50.4 W h kg-1 , in 1 M Et4 NBF4 electrolyte). This excellent electrochemical performance and facile effective synthesis of band gap-tunable BCN materials will provide a promising strategy for configuring nanostructured multiple compound electrodes for other energy storage and conversion devices.