Green synthesis of NiO nanostructured materials using Hydrangea paniculata flower extracts and their efficient application as supercapacitor electrodes

Abstract

In this report, for the first time, we have applied green synthesis NiO nanoparticles (NiO-NPs) as an electrode material for supercapacitor (SC). Hydrangea paniculata flower extracts were used for the green synthesis of NiO-NPs. The green synthesized NiO-NPs is found to be 33nm with surface area of 78.472m2g−1 along with pore volume and pore size of 0.149cm3g−1 and 4.061nm. The green synthesized NiO-NPs based electrode exhibit high specific capacitance of 752, 709, 644, 603 and 581Fg−1 at current densities of 2.5, 5, 10, 20, and 40Ag−1, respectively, are revealing excellent capacitance retention even at a high current density. More notably, the NiO-NPs electrodes also show outstanding cycling stability up to 5000cycles at 10Ag−1 without discernable capacitance fading. This superior electrochemical performance of NiO-NPs is mainly attributed to the nano-dimention of the particles, which shorten the diffusion path lengths for both ions and electrons, ease migration during the rapid charge-discharge process and consequently improve the effective electrochemical utilization of electroactive material.