Hydrothermal synthesis of Ni-based metal organic frameworks/graphene oxide composites as supercapacitor electrode materials

As electrode materials, metal-organic frameworks always have low electrical conductivity and poor structural stability, which limits its applications in electrochemical fields. Here, Ni-BPDC/GO composites are synthesized using graphene oxide (GO) as a substrate and 4,4 '-biphenyldicarboxylic acid (BPDC) as an organic ligand via a hydrothermal approach. The growth mechanism of the Ni-BPDC and Ni-BPDC/GO composites is proposed. In the composites, highly dispersed Ni-BPDC macro-nanostrips are supported on the GO surface in parallel. The presence of GO does not affect the growth and crystalline structure of Ni-BPDC. Compared with the Ni-BPDC, Ni-BPDC/GO composites exhibit higher specific capacitance, rate capability, and operating current density through lowering intrinsic resistance, charge-transfer resistance, and ion diffusion impedance. Moreover, the assembled Ni-BPDC/GO-3//reduced graphene oxide (rGO) asymmetric supercapacitor has large specific capacitance, good cycling stability, and high energy density (16.5 W h/kg at 250 W/kg). Hence, Ni-BPDC/GO composites are a potential electrode material for supercapacitors.