Fundamental Processes in Surface Photocatalysis on TiO2

` Because of the potential applications of TiO2 in photocatalytic hydrogen production and pollutant degradation, over the past few decades we have witnessed increasing interest in and effort toward developing TiO2-based photocatalysts, and improving the efficiency and exploring the reaction mechanisms at the atomic and molecular levels. Because surface science studies on single crystal surfaces under ultrahigh vacuum (UHV) conditions can provide fundamental insights into these important processes, both the thermo- and photo -chemistry on TiO2, especially on rutile TiO2(110) surfaces, have been extensively investigated with a variety of experimental and theoretical approaches. In this review, commencing with the properties of TiO2, we then focus on charge transport and trapping, and electron transfer dynamics. Next, we summarize recent progress made in the study of elementary photocatalytic chemistry of methanol on mainly rutile TiO2(110), as well as in some studies on rutile TiO2(011) and anatase TiO2(101). These studies have provided fundamental insights into surface photocatalysis and stimulated new investigations in this exciting area. The implications of these studies for the development of new photocatalysis models are also discussed.