Morphology well-controlled synthesis of NiO by solvothermal reaction time and their morphology-dependent pseudocapacitive performances

Abstract Synthesis of nickel oxide (NiO) nanomaterials with well-controlled morphologies is crucial to obtain superior electrochemical properties. Herein, we present a facile solvothermal route for the fabrication of three different morphologies NiO containing particles, honeycomb and three-dimensional (3D) nanoflower by adjusting the solvothermal reaction time. The possible mechanism for the formation process of the hierarchical 3D nanoflower architecture is investigated and proposed. The morphology and crystal structure of the as-prepared NiO were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the Brunauer–Emmett–Teller method (BET). The effects of morphologies on the electrochemical performances were systematically studied. It was found that NiO with flower-like structure exhibited the highest specific capacitance (364 F g −1 at 1 A g −1 ), excellent rate capability (64% capacitance retention from 1 A g −1 to 10 A g −1 ) and excellent cycling stability (no decrease in specific capacitance after 1200 test cycles).