Hydrothermal synthesis of novel Mn1/3Ni1/3Co1/3MoO4 on reduced graphene oxide with a high electrochemical performance for supercapacitors

The novel chemical composition of pristine Mn_1/3Ni_1/3Co_1/3MoO₄ (MNC) and Mn_1/3Ni_1/3Co_1/3MoO₄ dispersed in various percentages of reduced graphene oxide (MNC/rGO) composites were prepared via the one-step hydrothermal method. X-ray diffraction (XRD) patterns showed pure crystalline phase CoMoO₄ for the heat treated powder at 350 °C. Fourier Transform Infrared (FT-IR) spectra showed that the chemical band structure of Mn_1/3Ni_1/3Co_1/3MoO₄ corresponds to the strong vibrational bands of MoO, MoO and MoOMo bonds. X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of Mn, Ni, Co, Mo, C and O elements and its valance in the MNC/rGO powder. Field Emission Scanning Electron Microscope (FE-SEM) images displayed the nanorods morphology of the MNC/rGO powders. High-resolution Transmission Electron Microscopy (HR-TEM) images showed the morphology of MNC nanorods wrapped with the reduced graphene oxide of the MNC/rGO composite. The MNC/rGO composite displayed the highest specific capacitances of 1750 F g⁻¹ at 1 A g⁻¹ in 3 M KOH. The MNC/rGO composite demonstrated a better cycling stability with a cycling efficiency of 85.5% after 5000 cycles at 10 A g⁻¹. The high rate performances, good reversibility and capacity retention at a range of current densities were demonstrated the structural stability of the MNC/rGO composite. The high energy density of 38.8 W h kg⁻¹ at a constant power density of 200 W kg⁻¹was achieved for the MNC/rGO composite.