X-ray diffraction (XRD) patterns of the as-prepared products were acquired from a Bruker D8 Focus diffractometer (Germany) with Cu Ka radiation operated at 40 kV and 40 mA. Scanning electron microscopy (SEM) was conducted on a Hitachi S4300 field emission scanning electron microscope (FE-SEM). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were performed on a JEOL JEM-200CX transmission electron microscope at an acceleration voltage of 200 kV. The powder samples were added to carbon-coated copper grids