Characterizations
Carbon contents in the prepared samples were measured by
thermal gravimetric analysis (TGA, Q20). The crystalline phases of
samples were investigated by X-ray powder diffraction (XRD,
Rigaku D/MAX 2500). The morphology and element distribution of
samples were observed using Scanning Electron Microscopy (SEM,
SU-70), Transmission Electron Microscopy (TEM, H-7650) and