The specific surface area and pore size distribution
of catalysts were measured by N2 adsorption in
a Micromeritics ASAP 2000. A diffusive reflective
UV–VIS spectrophotometer (Hitachi U-3410) was
employed to measure the UV–VIS absorption and estimate
the bandgap of the catalysts. The particle size
distribution in aqueous solution was obtained using
a Coulter LS230 particle size analyzer. Transmission
electron microscopy (TEM) and scanning electron
microscopy with energy dispersive X-ray spectrometer
(SEM-EDX, Philips XL30, EDAX DX4) were
used to observe the morphology of catalysts and estimate
the elemental ratio. The crystalline phase was
identified by X-ray diffraction (MAC MO3XHF). The
chemical status and shift of the catalyst surface were
analyzed by X-ray photoelectron spectroscopy (XPS).
XPS measurements were taken on a VG Microtech
MT500 spectrometer, operated with a constant pass
energy of 50 eV and with Mg K radiation as the
excitation source (hν = 1253.6 eV). The catalyst was
pressed into a pellet, and then adhered on sample
holder by carbon tape. Oxygen (1 s, 530.7 eV for
TiO2) [6] and carbon (1 s, 284.5 eV) were taken as
internal standards for binding energy calibration. The
fluorescence spectra of catalysts were measured by a
Jasco FP-777 fluorescence spectrophotometer at an
excitation wavelength of 370 nm.