2D nitrogen-doped porous carbon nanosheets derived from cellulose nanofiber/silk fibroin nanohybrid cellular monoliths with promising capacitive performance

摘要

2D nitrogen-doped porous carbon nanosheets are prepared from cellulose nanofiber/silk fibroin nanohybrid cellular monoliths via unidirectional freeze-shaping technique, carbonization, and CO2 activation processes. The micromorphology of the cellulose nanofiber/silk fibroin nanohybrid cellular monoliths can be effectively controlled by simply changing the content of silk fibroin. The 2D nitrogen-doped porous carbon nanosheets (NPCN-X, X represents the content of silk fibroin), inherited from different cellular monolith, show a distinct micromorphology. The NPCN-50 exhibits the best electrochemical performance due to its 2D nanostructure, abundant multi-scale through pores, high specific surface area (about 1882 m(2) g(-1)), and appropriate surface N/O-doping. The largest gravimetric capacitance value is about 329.9 F g(-1) at a current density of 0.25 A g(-1). The energy density reaches as high as 37.5 Wh kg(-1) at a power density of 186.3 W kg(-1). The NPCN-50 also exhibits excellent electrochemical cycling stability.