Colloidal synthesis of NiMn2O4 nanodisks decorated reduced graphene oxide for electrochemical applications

•Spinal NiMn2O4 nanodisks decorated reduced graphene oxide (rGO) were prepared.•NiMn2O4/rGO composite analyzed as electro-active electrode for electrochemical sensor and supercapacitors.•NiMn2O4/rGO composite modified GCE showed the high sensitivity of 78.56 mA.mM−1cm−2 towards the acetylacetone chemical.•Electrochemical supercapacitors with NiMn2O4/rGO electrode possessed reasonably high specific capacitance of 356 Fg−1.