Microstructural Characterization of a Fumed Titanium Dioxide Photocatalyst

We present observations of a fumed titania photocatalyst (Degussa, P25) using high resolution TEM and X-ray diffraction. The catalyst was observed as-received and after being used for photocatalytic destruction of salicylic acid. The characterization results suggest that the photocatalyst consists of individual single crystal particles of the rutile and anatase phases of titania; no amorphous titania particles could be identified conclusively. We also did not detect any particles of anatase that were covered by a layer of rutile, as proposed previously by Bickley et al. ( J. Solid State Chem., 92, 178, 1991). No changes were seen in the titania after it was used for photocatalysis of salicylic acid at pH 6 for short times (less than 1 hr).