A Hybrid Amorphous Crystalline TiO2 Material with Enhanced Photocatalytic Performance

Whereas crystalline TiO2 is widely used as a photocatalyst for solar energy conversion, the use of amorphous TiO2 is limited by diminished performance. Herein, the highly active photocatalyst composed of low-crystalline TiO2 prepared by simple heat treatment of amorphous material is reported. Transmission electron microscopy, X-ray diffraction, Raman, X-ray absorption spectroscopy, and scanning transmission electron microscopy show that the low crystalline catalyst is hetero-phase amorphous/anatase (m(amorphous): m(anatase) approximate to 2:3). Enhanced photocatalytic performance derives from the difference in conduction band potential between the phases, which promotes charge transfer and photochemical conversion. The photocatalyst calcined at 300 degrees C (T-300) exhibits superior performance over commercial P25 (Degussa) for elimination of perrhenate, Re(VII), a surrogate for Tc(VII), and furthermore remains stable after several recycles. The high efficiency of Re(VII) removal by T-300 is likely to correlate with active radicals .CO2- in the TiO2/HCOOH system. In addition to identifying a simple and effective photocatalyst, the results more generally elucidate titania-based photocatalysis.