Abstract:
Composites of mixed transition metal oxides with different forms of carbon have been studied as a high-performance electrode material for supercapacitor devices. The currently practiced synthetic strategies for such materials are based on the incorporation of an oxide phase into a preformed porous carbon matrix made of graphene, graphene-derivatives, activated carbon, carbon fiber, carbon nanotubes, etc. The two major drawbacks of this method are; firstly, the composite has a significantly reduced surface area compared to that of the carbon matrix and secondly, it potentially leads to an inhomogeneous dispersion of the oxide phase inside the carbon matrix. Here, we report a simple, generalizable and novel method to synthesize mixed metal oxide-graphene mesoporous hybrid material, with the example of a homogeneously distributed nickel ferrite (NiFe2O4) nanoparticles as the oxide phase. Literature survey indicates that, this is the first bottom-up synthesis attempt to such a material for supercapacitor application, where the synthesis starts with a homogeneous solution containing 3,5-dimethylphenol as the precursor for graphene and metal nitrates (iron nitrate and nickel nitrate) as precursors for NiFe2O4. A gel obtained after the polymerization of the phenol is further processed in a few steps, facilitating the simultaneous formation of a highly crystalline mesoporous graphene matrix and homogeneously distributed nano-sized NiFe2O4 particles. The maximum heat treatment temperature used in the synthesis is 600oC. The NiFe2O4-Graphene mesoporous hybrid electrode material showed a relatively high specific surface area of 308.16 m2/g and a high specific capacitance of 883.8 F g−1, at a current density of 1 A g−1.
