Investigation on structural, optical and electrochemical behavior of NiO/ZnMn2O4 ternary nanocomposites via two-step synthesis approach for supercapacitor application

The present investigation deals with the synthesis of nickel oxide (NiO)/zinc manganite (ZnMn 2 O 4 ) nanocomposites (NCs) by a two-step approach. The powder X-ray diffraction (PXRD) pattern revealed the existence of face-centered cubic (FCC) phase of NiO and tetragonal rutile phase structure of ZnMn 2 O 4 in NiO/ZnMn 2 O 4 NCs. The optical properties of NiO/ZnMn 2 O 4 NCs have been investigated by the UV-diffuse reflectance Spectroscopy (UV-DRS) and photoluminescence (PL) spectral analysis. The surface morphology and elemental composition of NiO/ZnMn 2 O 4 NCs was investigated by field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectrum (EDX) analysis. The surface area and the nature of porosity of the samples were analyzed using Brunauer–Emmett–Teller (BET) method. The electrochemical properties were investigated from the cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. In 0.5 M potassium hydroxide (KOH) electrolyte solution, NiO/ZnMn 2 O 4 NCs exhibited higher specific capacitance of 886 F/g at a current density of 1Ag −1 with high cyclic stability over 1000 charge–discharging cycles. Thus, the result demonstrates that the prepared NiO/ZnMn 2 O 4 NCs is a promising electrode material for future energy-storage devices.