Natural nanofiber-based stacked porous nitrogen-doped carbon/NiFe2O4 nanohybrid nanosheets

Abstract

The traditional hydrolysis/hydrothermal two-step preparation method of carbon/inorganic nanohybrid material usually exhibit the disadvantage of aggregation and precipitation. Therefore, the above method has certain difficulty in the synergistically regulation of the aggregation morphology and microscopic morphology of carbon/inorganic nanohybrid materials. In this paper, cellulose nanofiber and chitin nanofiber are used as the carrier material of inorganic nanomaterials, which can maintain the uniform and stable dispersed state during the hydrolysis of metal ions and hydrothermal treatment. The uniform inorganic nanoparticles uniformly distributed in the randomly stacked nanosheets even if the total content of metal ions increases to 6 mmol. The natural nanofibers/NiFe2O4 nanoparticles composite nanosheets with adjustable stacked pore structure can be prepared from natural nanofibers/NiFe2O4 nanoparticles composite hydrogel via unidirectional freeze-shaping. The carbonization temperature and carbonization time are more effective in synergistically regulation of the stacked porous nitrogen-doped carbon/NiFe2O4 nanohybrid nanosheets. Extending carbonization time or increasing carbonization temperature not only allows the growth of inorganic nanomaterials, but also causes damage to the nanosheets (such as broken pore and the small, wrinkled morphology of the nanohybrid nanosheets). NC/NiFe2O4-1.5/700/3 exhibits the highest gravimetric capacitance (up to 458 F g−1 at a constant current density of 0.5 A g−1).