Highly improved supercapacitance properties of MnFe2O4 nanoparticles by MoS2 nanosheets

Manganese ferrite (MnFe 2 O 4 ) nanoparticles were synthesized via a hydrothermal method and combined with exfoliated MoS 2 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. Field-emission scanning electron microscopy images showed the uniform and dense distribution of MnFe 2 O 4 nanoparticles (~ 10 nm) on few-layer MoS 2 nanosheets (~ 2 to 3 µm in width). UV-visible absorption photospectrometry indicated a decrease in the bandgap of MnFe 2 O 4 by MoS 2 , resulting in a higher conductivity that is suitable for capacitance. Electrochemical tests showed that the incorporation of MoS 2 nanosheets largely increased the specific capacitance of MnFe 2 O 4 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 MnFe 2 O 4 /MoS 2 nanocomposite in a two-cell asymmetric supercapacitor setup. A density functional theory study was also performed on the MnFe 2 O 4 /MoS 2 interface to analyze how a MoS 2 monolayer can enhance the electronic properties of MnFe 2 O 4 towards a higher specific capacitance.