Transition mixed-metal molybdates (MnMoO4) as an electrode for energy storage applications

Abstract

MnMoO4 nanoparticles were synthesized by employing solvothermal method at optimized experimental condition to explore their electrochemical properties. The fundamental characterization studies such as X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectra confirmed the formation of pure phase of monoclinic crystal structure with C2/m space group. X-ray photoelectron spectroscopy studies revealed that the core-level Mn-2p spectrum peaks observed at 641.2 eV can be attributed to Mn-2p3/2 and that at 654.1 eV can be indexed to the binding energy of Mn-2p5/2. Major infrared peaks observed at 725, 800, 867, and 946 cm−1 could be designated to the characteristics bands of tetrahedral MoO4 groups in MnMoO4 nanoparticles. Raman peaks observed at 351, 823, 886, and 932 cm−1 corresponded to characteristics bands for MnMoO4 nanoparticles. The cyclic voltammetry studies at different scan rates (i.e., 10, 20, 30, 50, 80, and 100 mV s−1) were performed for all three MnMoO4 nanoparticles and displayed similar redox peaks in the positive and negative current regions, reflecting the pseudocapacitive nature. From galvanostatic charge–discharge profiles, it was found that MnMoO4 nanorods (R2) show high- capacitance of 697.4 F g−1 at 0.5 A g−1 current density and 40% increment in specific capacitance than other nanoparticles and can be considered as suitable nanomaterials as electrode for energy storage applications.