Elucidating the Defect-Induced Changes in the Photocatalytic Activity of TiO2

The adsorption and subsequent photo-oxidation of carbon monoxide on the anatase TiO2(101) and rutile TiO2(110) single crystal surfaces was investigated using low temperature X-ray photoelectron spectroscopy. Anatase was shown to significantly outperform rutile in terms of the rate of carbon dioxide yield on the stoichiometric surface, and further to this, the presence of defects was shown to heavily influence the photocatalytic efficiency. The oxidation rate was reduced on anatase but increased on rutile. This change is attributed to the location of defects within the crystal structure and is further discussed in this work. These findings are of significant importance and demonstrate the possibilities of defect engineering in photocatalysis.