Highly improved supercapacitance properties of MnFeO nanoparticles by MoS nanosheets.

Manganese ferrite (MnFeO) nanoparticles were synthesized via a hydrothermal method and combined with exfoliated MoS nanosheets, and the nanocomposite was studied as a supercapacitor. X-ray diffractometry and Raman spectroscopy confirmed the crystalline structures and structural characteristics of the nanocomposite. Transmission electron microscopy images showed the uniform size distribution of MnFeO nanoparticles (~ 13 nm) on few-layer MoS nanosheets. UV-visible absorption photospectrometry indicated a decrease in the bandgap of MnFeO by MoS, resulting in a higher conductivity that is suitable for capacitance. Electrochemical tests showed that the incorporation of MoS nanosheets largely increased the specific capacitance of MnFeO from 600 to 2093 F/g (with the corresponding energy density and power density of 46.51 Wh/kg and 213.64 W/kg, respectively) at 1 A/g, and led to better charge-discharge cycling stability. We also demonstrated a real-world application of the MnFeO/MoS nanocomposite in a two-cell asymmetric supercapacitor setup. A density functional theory study was also performed on the MnFeO/MoS interface to analyze how a MoS monolayer can enhance the electronic properties of MnFeO towards a higher specific capacitance.