Single Molecule Photocatalysis on TiO 2 Surfaces

Heterogeneous photocatalysis has been widely applied in various fields, such as photovoltaic cell, solar water splitting, photocatalytic pollutant degradation, and so on. Therefore, the reaction mechanisms involved in these important photocatalytic processes, especially in TiO 2 photocatalysis, have been extensively investigated by various surface science techniques in the past decade. In this review, we highlight the recent progress that provides fundamental insights into TiO 2 photocatalysis through direct tracking the evolution of single molecule photochemistry on TiO 2 single crystal surfaces using a combination of scanning tunneling microscopy (STM) and other surface science techniques. Insight into the structures of various TiO 2 surfaces is discussed first, which provides a basic concept on TiO 2 . Afterward, the details of the single molecule photocatalysis of several important molecules (water, alcohols, and aldehydes) on the model TiO 2 surfaces are presented, which are trying to probe bond cleavages and the roles of adsorption sties and adsorption states in TiO 2 photocatalysis step-by-step. Last, challenges and opportunities in single molecule photocatalysis on TiO 2 are discussed briefly.