Effect of the noncovalent functionalization of graphite nanoflakes on the performance of MnO2/C composites

Abstract

In this paper, graphite nanosheets were modified by aminopyrene (Amin), 1-pyrenecarboxylic acid (PCA) and cetyltrimethyl ammonium bromide. Based on physical (field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy) and electrochemical tests (cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charging/discharging curves), their physical and chemical properties were investigated. The physical characterization and electrochemical performance analysis indicated that the different reducing agents, technical methods and small organic molecules significantly influenced the precipitation of MnO2. When the small organic molecule was PCA, the G/MnO2 composite material had the best electrochemical capacity and stability. PCA possesses four rings; therefore, PCA can interact with graphite layers and peel off the graphite to form MnO2/single-layer graphene. During the loading of MnO2, PCA did not influence the structure of MnO2 crystals. After modification by PCA, the MnO2/C composite possessed long-term cycling stability. The changes in the morphological and structural evolutions in nanocrystalline MnO2 for the MnO2/C composite differed from those observed for pure MnO2.