Mn2O3–Co3O4 nanocomposites as advanced electrode materials: achieving high specific capacitance and excellent cycling stability

Abstract

Mn₂O₃ particles were synthesized via a hydrothermal process and subsequently coated with Co₃O₄ to develop Mn₂O₃–Co₃O₄ composite particles as a supercapacitor electrode material. X-ray diffraction (XRD) confirms that the samples are crystallized and contain both Mn₂O₃ and Co₃O₄ phases. Mn₂O₃–Co₃O₄ nanoparticles with 40 min of reaction time displayed the highest specific surface area of 15.67 m² g⁻¹. The electrochemical behavior of Mn₂O₃–Co₃O₄ electrodes was investigated using charge/discharge measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) in a 1 M KOH electrolyte at room temperature. The specific capacitance (C_SP) of Mn₂O₃–Co₃O₄-40 min exhibits an excellent value of 1289.6 F g⁻¹ (an 81.8% increase compared to the uncoated Mn₂O₃). In addition, the corresponding nanoparticles give the highest energy density of 35.3 Wh kg⁻¹ at a power density of 394.5 W kg⁻¹. Mn₂O₃–Co₃O₄ electrodes show good specific capacitance retention of above 95% after 5000 cycles of continuous charge/discharge. The Co₃O₄ coating on Mn₂O₃ not only enhances electrical conductivity but also introduces multiple redox couples (Mn²⁺/Mn³⁺, Mn³⁺/Mn⁴⁺, and Co²⁺/Co³⁺), enabling rapid and reversible redox reactions. This synergistic effect significantly enhances charge transfer kinetics and overall electrochemical performance, indicating that the Mn₂O₃–Co₃O₄ nanoparticle is a highly promising electrode material for next-generation supercapacitors.