In the present work, the effect of quenching on surface defect and photocatalytic activity of the solvothermal-derived nanocrystalline TiO2 with average crystallite sizes between 9 and 13 nm was extensively studied. On the basis of CO2-TPD (TPD = temperature-programmed desorption) and XPS (XPS = X-ray photoelectron spectroscopy) results, it was found that the amount of Ti3+ surface defects and photocatalytic activities of the prepared TiO2 depended strongly on the type of quenching media used in the following order:  H2O2-RT > H2O2-373K > H2O-RT > H2O-373K > air-RT > air-373K, where RT = room temperature. However, the TiO2 sample that was slowly cooled after calcination (the nonquenched sample) also possessed a significant amount of Ti3+ surface defects and high photocatalytic activity to a degree similar to that quenched in H2O-RT. The effect of quenching was more pronounced on the smaller crystallite size TiO2 than on the larger ones due probably to its higher surface energy so that oxygen atoms were released more easily.

No abstract

No abstract

No abstract