Direct Imaging Single Methanol Molecule Photocatalysis on Titania

Photocatalysis of a single methanol molecule on the TiO2(110) surface was investigated using a high-resolution scanning tunneling microscopy (STM) technique. Three different types of elementary methanol photocatalytic processes, methanol photodissociation, photoinduced migration of formaldehyde, and formaldehyde photodesorption, were clearly observed. Detailed chemical structures of the intermediates were obtained through careful comparisons between experimental STM images and theoretical simulations based on density functional theory (DFT) calculations. This work demonstrates that elementary photocatalytic processes of a single methanol molecule on the surface can be followed step by step using advanced STM imaging techniques. Such a study can provide unprecedented insights into the surface photocatalytic processes and will greatly help us to understand photocatalysis at the most fundamental level.