Ultrathin MnO2 nanosheets grown on fungal conidium-derived hollow carbon spheres as supercapacitor electrodes
Development of biomass-derived carbon/MnO2 composites for energy applications has recently been attracting tremendous attention. However, the combination of MnO2 nanosheets and conidia-derived hollow carbon spheres for supercapacitor applications has never been realized. In this work, we develop a facile method to grow MnO2 nanosheets on hollow carbon spheres derived from Aspergillus flavus conidia. Ultrathin MnO2 nanosheets are uniformly grown on the surface of conidium-derived hollow carbon spheres. Sulfur element from the conidia is doped in the composites and the amount of MnO2 in the material is ∼50.2 wt%. The as-prepared MnO2–carbon sphere composited electrode possesses a high specific capacitance of 263.5 F g−1 at 1 A g−1. After 2000 cycles, the specific capacitance value remains 83% of retention and the coulombic efficiency remains as high as 94%, demonstrating the excellent cycling stability.