Ni-MOF derived NiO/C nanospheres grown in situ on reduced graphene oxide towards high performance hybrid supercapacitor

In this paper, NiO nanoparticles uniformly embedded in spherical carbon matix in situ grown on reduced graphene oxide (rGO) has been successfully fabricated via a simple pyrolysis of nickel metal organic framework (MOF) precursor self-assembled on graphene oxide. This interaction between the carbon and the NiO can significantly maximize the surface of NiO for pseudocapacitance, provide effective electronical transmission path and improve the ionic absorbability and conductivity. As a result, the NiO/C/rGO hybrid electrode demonstrates high specific capacity (496 C g(-1) at current density of 1 A g(-1)) and good cycling stability. Moreover, a hybrid supercapacitor assembled by NiO/C/rGO and a hierarchical porous carbon derived from sodium citrate can deliver a high energy density of 35.9 Wh kg(-1) at a power density of 749.1 W kg(-1), and extraordinary cycling stability (120% retention after 3000 cycles). It has been demonstrated that the carbon matrix derived from the linker molecules in Ni-MOF, which maintains close contact with both the size-controlled NiO nanocrystals and the electronic conductive rGO, is vital to synergize the electric double layer capacitance from the carbon materials and the battery-type behavior from NiO for high-performance energy storage. (C) 2019 Elsevier B.V. All rights reserved.