Natural nanofibers stacked porous nitrogen-doped carbon nanosheets with promising capacitive performance

There are plenty of stacked pores with various scales in nature. The size of stacked pores is depending on the morphology and size of stacked materials. Inspired by this phenomenon, the hierarchical porous carbon-based electrode materials with novel nanostructure can be obtained via nanomaterials stacking method. In this study, cellulose nanofiber and chitin nanofiber are selected as the precursor of the stacked porous nitrogen-doped carbon nanosheets due to their unique nanostructure and infusible physical properties. They are randomly stacked and compacted in the gaps between the rapidly growing ice crystals. The pore sizes of carbon nanosheets are mainly on the mesopore and micropore scale. After carbonization, large-scale graphene-like carbon nanosheets structure and stacked pores are effectively retained. The natural nanofiber-based carbon nanofibers closely connect each other to form a compacted 3D network that facilitates the electron transmission. The stacked pore size distribution (especially stacked micropores), specific surface area, heteroatom functionalities and graphitization degree of stacked porous nitrogen-doped carbon nanosheets are significantly affected by carbonization temperature. When the content of chitin nanofiber is 50% and the carbonization temperature is 700 °C, the stacked porous nitrogen-doped carbon nanosheet exhibits better electrochemical performance.

Stacked porous nitrogen-doped carbon nanosheets are prepared from cellulose nanofiber/chitin nanofiber stacked nanosheets by using the random stacking of natural nanofibers in the gaps between rapidly growing ice crystals, which their properties can be effectively controlled by carbonization temperature.