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Ultrathin MnO₂ nanosheets grown on fungal conidium-derived hollow carbon spheres as supercapacitor electrodes

Mao, Cuiping, Liu, Sangui, Pang, Lei, Sun, Qi, Liu, Yang, Xu, Maowen, Lu, Zhisong
RSC advances 2016 v.6 no.7 pp. 5184-5191
Aspergillus flavus, capacitance, carbon, conidia, electrodes, energy, fungi, manganese dioxide, nanosheets, sulfur
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.