Characterization. The X-ray diffraction (XRD) patterns were recorded on a Japan Rigaku D/Max-RB X-ray diffracto- meter with Cu KR radiation (λ ) 1.54178 Å). Transmission electron microscopy (TEM) images were taken on a JEOL JEM- 200CX with an accelerating voltage of 200 kV, and the high- resolution transmission electron microscopy (HRTEM) image was taken on a JEOL JEM-2010F with an accelerating voltage of 200 kV. Selected-area electron diffraction (SAED) was also taken on a JEOL JEM-2010F field emission transmission electron microscope. Fourier transform infrared (FTIR) spectra were obtained on an AVATAR370 spectrometer. The nitrogen adsorption and desorption isotherms at 77 K were measured with a Micrometrics ASAP 3000 analyzer. Before measurement, the samples were degassed in vacuo at 200 °C for at least 6 h.