Synthesis of graphene oxide anchored porous manganese sulfide nanocrystals via the nanoscale Kirkendall effect for supercapacitors

Abstract

Graphene oxide (GO) anchored porous manganese sulfide nanocrystals (MnS/GO-NH₃) were obtained via a facile hydrothermal method based on the Kirkendall effect. The honeycomb-like manganese sulfide nanocrystals (40–80 nm) and the three-dimensional sandwich structure endow the MnS/GO-NH₃ with high supercapacitive performance when it was used as a supercapacitor material. The MnS/GO-NH₃ electrode exhibits high specific capacitance (390.8 F g⁻¹ at 0.25 A g⁻¹), high rate capacity (78.7% retention at 10 A g⁻¹) and stable cycle life (81.0% retention after 2000 cycles), which are superior to those of GO anchored MnS floccules (MnS/GO) and manganese hydroxide (Mn(OH)₂/GO). As a novel material for supercapacitors, the charge–discharge mechanism of the MnS/GO-NH₃ composite is proposed via detailed investigation. Asymmetric supercapacitors, assembled with MnS/GO-NH₃ as the positive material and activated carbon as the negative electrode, reveal a high specific capacitance (73.63 F g⁻¹), a high energy density of 14.9 W h kg⁻¹ at 66.5 W kg⁻¹ and even 12.8 W h kg⁻¹ at a high power density of 4683.5 W kg⁻¹.