Yeasts-derived nitrogen-doped porous carbon microcapsule prepared by silica-confined activation for supercapacitor

Biomass is a common carbon precursor, because of its low cost, easy access and wide sources. However, direct pyrolysis of biomass usually leads to some disadvantages such as morphology destruction, low surface area and poor porosity. Herein, a silica-confined activation strategy is developed to prepare nitrogen-doped (N-doped) porous carbon microcapsule using the renewable biomass carbon precursor of yeasts. The yeasts are wrapped by a dense silica shell, forming a limited space, which can effectively avoid the destruction of yeast morphology during pyrolysis. The pyrolysis gas derived from yeast cannot overflow due to the limitation of confined space, and it plays an in-situ activator to result in layer structure with thin wall, abundant pores and high specific surface area (870 m² g^-1). Moreover, the N-doped porous carbon microcapsule possesses a higher certain of N-doping than the carbon product derived from direct pyrolysis of yeasts. As electrode materials in supercapacitor, the N-doped porous carbon microcapsule exhibits high capacitance of 316 F g^-1 at 1 A g^-1 with obvious enhancement of electrochemical performance compared with the carbon product derived from direct pyrolysis of yeasts, indicating the promise as a new electrode material in energy storage.