Microwave hydrothermal synthesis of α-MnMoO nanorods for high electrochemical performance supercapacitors.

Pristine α-MnMoO nanorods were facilely prepared co-precipitation (Cp) and microwave hydrothermal (MH) methods. X-ray diffraction (XRD) patterns showed pure monoclinic crystalline phase α-MnMoO for the heat treated powder at 500 °C. Fourier Transform Infrared (FTIR) spectra showed that the chemical bond structure of α-MnMoO corresponds to the strong vibrational modes of Mo-O-Mo, Mo-O and Mo[double bond, length as m-dash]O. Raman spectra showed the structural bonding and crystalline nature of α-MnMoO. Field Emission Scanning Electron Microscope (FE-SEM) images exposed the nanorod shape of the α-MnMoO powder, with diameters of ∼200 nm and lengths of ∼1.6 μm. Electrochemical studies of the Cp- and MH-MnMoO nanorods with 2 M NaOH as the electrolyte showed specific capacitances of 143 F g and 551 F g, respectively, at a 1 A g constant discharge current density. Cyclic voltammetric (CV) studies of the MH-MnMoO nanorods at various scan rates revealed the presence of redox pairs, suggesting a pseudocapacitive nature. The structural stability at different current densities demonstrated the high rate performances and good reversible capacity retention of the calcined MH-MnMoO nanorods. A cycling life stability study of MH-MnMoO demonstrated a good capacity retention of 89% of the initial specific capacitance at 5 A g after 1000 cycles.