Novel carbonaceous ZnO composite prepared through inert-ambient pyrolysis of the zinc anthranilate complex

In this work we present the analysis of products of the pyrolysis, at 600 °C, of zinc anthranilate complex in open air and in the nitrogen ambient of a sealed tube. The resulting powder samples were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (FESEM), and transmittance electron microscopy (HR-TEM). Open-air pyrolysis (OAP) yields well-crystallized ZnO, whereas sealed-tube pyrolysis (STP) produces a black powder that is found to be a composite (ZnO/C) of graphitic carbon and nanocrystalline, nearly monodisperse ZnO. The composite is carbon-rich. The relatively large size of ZnO crystallites from OAP and their much smaller size in the STP product suggest that carbon formation in the sealed tube restricts the growth of ZnO nanocrystals. When ZnO/C was annealed in air at 650 °C for 1 h, the oxide crystallites retained their average size, with all carbon removed. To investigate the possibility of using ZnO/C as electrode material in capacitors, electrochemical investigations electrode were carried out using cyclic voltammetry and galvanostatic charge-discharge, with 0.5 M KOH as electrolyte. The specific capacitance of the ZnO/C composite was found to be 124.7 F g−1 at 5 mV s−1 scan rate, indicating the suitability of ZnO/C as electrode material because of the measured voltammograms and charge-discharge characteristics.