A comparison of mixed phase titania photocatalysts prepared by physical and chemical methods: The importance of the solid–solid interface

Mixed phase titania photocatalysts, such as Degussa P25, typically show higher photocatalytic activity than pure phase titania, as reported by many researchers. Our previous experimental results indicate that the solid–solid interface is a key factor in enhancing the photocatalytic reactivity of mixed phase titania and may be the location of catalytic “hot spots”. In this study, titania photocatalysts consisting of varying amount of anatase and rutile phases are prepared by reactive dc magnetron sputtering and by a modified sol–gel method. These titania materials are characterized with a variety of techniques and are tested in the photocatalytic degradation of acetaldehyde. Mixed phase titania thin films prepared by magnetron sputtering have a high density of anatase–rutile interfaces and display the highest photocatalytic activity among the catalysts tested. Studies by electron paramagnetic resonance spectroscopy show a unique distribution of charge trapping sites which are characteristic of the sputtered films. The role of anatase–rutile interface to separate charge and improve the photoactivity of mixed phase materials is discussed.

Graphical abstractMixed phase titiana prepared by reactive magnetron sputtering demonstrated better photocatalytic activity than those prepared by other methods. The improved photoactivity is suggested to be associated with a unique distribution of charge trapping sites and a high density of solid–solid interfaces between anatase and rutile phases in the sputtered titania materials.Figure optionsDownload full-size imageDownload as PowerPoint slide