Synthesis of a MnO2/NiCo2O4 composite by electrostatic self-assembly and its electrochemical performance

Abstract

A hetero-layered MnO2/NiCo2O4 composite was fabricated according to an electrostatic self-assembly process between negatively charged MnO2-layered nanosheets and positively charged Co-Ni-layered double hydroxide nanosheets, followed by a heat-treatment process. The morphology, composition, and microstructure characteristics of the resulting material were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectrometry, atomic absorption spectrometry (AAS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Furthermore, the electrochemical behaviors of the composite were evaluated by cyclic voltammetry (CV), galvanostatic chargedischarge, and electrochemical impedance spectroscopy (EIS). The test results indicated that the hetero-layered composite showed porous stacking structure, which increased the effective liquid-solid interfacial area, and provided a fast path for the insertion and extraction of electrolyte ions. A specific capacitance of 482 F·g-1 was obtained in the potential window from-0.6 to 0.45 V at a current density of 1 A·g-1. These values were therefore superior to those of pure MnO2 or pure NiCo2O4. © Editorial office of Acta Physico-Chimica Sinica.