One-pot synthesis of a Ni–Mn3O4 nanocomposite for supercapacitors

• Ni–Mn3O4 nanocomposites have been synthesized simply.
• Mn3O4 particles were deposited on surface of Ni particles with OH functional groups.
• Ni–Mn3O4 composites could be quickly conditioned to birnessite-type MnO2.
• A specific capacitance of 230 F g−1 was obtained for Ni (17.3%)–Mn3O4 nanocomposite.

Ni–Mn3O4 nanocomposite has been prepared successfully by chemical oxidation in an alkaline solution of Mn2+ on the surface of Ni nanoparticles with OH functional groups using one-pot method. The obtained Ni–Mn3O4 nanocomposite was characterized using a scanning electron microscope (SEM), a transmission electron microscope (TEM), X-ray diffraction (XRD) analysis and various electrochemical techniques, such as cyclic voltammetry (CV), galvanostatic charge/discharge (GC/D) and electrochemical impedance spectroscopy (EIS). The average crystal sizes of Mn3O4 were found to decrease linearly with increasing Ni content in the Ni–Mn3O4 composite. The Ni–Mn3O4 nanocomposite could be easily conditioned and inverted to birnessite-type MnO2. A specific capacitance of 230 F g−1 (based on pure Mn3O4) was obtained for the Ni (17.3%)–Mn3O4 nanocomposite at a current rate of 0.25 A g−1, and 94% of the initial capacitance was retained after 1000 GC/D cycles at a current rate of 1 A g−1. It is concluded that the Ni–Mn3O4 nanocomposite is a promising electrode materials for supercapacitors.