Synthesis of multifunctional CuFe₂O₄-reduced graphene oxide nanocomposite: an efficient magnetically separable catalyst as well as high performance supercapacitor and first-principles calculations of its electronic structures

Here, we report an 'in situ' co-precipitation reduction based synthetic methodology to prepare CuFe₂O₄ nanoparticle-reduced graphene oxide (CuFe₂O₄-RGO) nanocomposites. First principles calculations based on Density Functional Theory (DFT) were performed to obtain the electronic structures and properties of CuFe₂O₄, graphene and CuFe₂O₄-graphene composites, and to understand the interfacial interaction between CuFe₂O₄ and graphene in the composite. The synergistic effect, which resulted from the combination of the unique properties of RGO and CuFe₂O₄ nanoparticles, was exploited to design a magnetically separable catalyst and high performance supercapacitor. It has been demonstrated that the incorporation of RGO in the composite enhanced its catalytic properties as well as supercapacitance performance compared with pure CuFe₂O₄. The nanocomposite with 96 wt% CuFe₂O₄ and 4 wt% RGO (96CuFe₂O₄-4RGO) exhibited high catalytic efficiency towards (i) reduction of 4-nitrophenol to 4-aminophenol, and (ii) epoxidation of styrene to styrene oxide. For both of these reactions, the catalytic efficiency of 96CuFe₂O₄-4RGO was significantly higher than that of pure CuFe₂O₄. The easy magnetic separation of 96CuFe₂O₄-4RGO from the reaction mixture and good reusability of the recovered catalyst also showed here. 96CuFe₂O₄-4RGO also demonstrated better supercapacitance performance than pure CuFe₂O₄. 96CuFe₂O₄-4RGO showed specific capacitance of 797 F g^-1 at a current density of 2 A g^-1, along with ∼92% retention for up to 2000 cycles. To the best of our knowledge, this is the first investigation on the catalytic properties of CuFe₂O₄-RGO towards the reduction of 4-nitrophenol and the epoxidation reaction, and DFT calculations on the CuFe₂O₄-graphene composite have been reported.