One-Step Gel Formation Method for the Synthesis of NiO-MnXOY Mixed Oxide Nanomaterials as a Prospective Supercapacitor Material

Composites of transition metal oxides are very well known for their excellent electrochemical performance. Herein, we have reported the preparation of a nano-architectured mixed metal oxide of NiO-Mn
_X
O
_Y
by using simple gel formation method towards high-performance electrochemical supercapacitor. The surface morphology of the mixed oxides was investigated by scanning electron microscope (SEM) and was found to be in nano-dimension with capsule shape. The X-ray diffraction (XRD) pattern demonstrated the highly crystalline structure of the mixed oxides. The quasi-rectangular CV curves of NiO-Mn
_X
O
_Y
in between (-0.4 to + 0.3 V) indicated almost ideal double-layer capacitive properties of the prepared material. However, the slightly distorted symmetrical triangular GCD confirmed the contribution of both electric double layer capacitance (EDLC), and pseudo capacitance over the total capacitance. The total specific capacitance of NiO-Mn
_X
O
_Y
was found to be 450 Fg
^-1
at a current density of 0.5 Ag
^-1
in 0.5 M Na
₂
SO
₄
aqueous electrolyte. A small half semicircle arcs at the high frequency region of Nyquist plot indicated the low charge transfer resistance of NiO-Mn
_X
O
_Y
oxide at the electrode and electrolyte interfaces which facilitated the large ionic charge storage capacity of the electrode material. The excellent capacitance performance of the as prepared material demonstrated the suitability of the material for the application in practical supercapacitors.