Molecular-Level Insights into Photocatalysis from Scanning Probe Microscopy Studies on TiO2(110)

The growing use of scanning probe microscopy (SPM) techniques in providing molecular-level insights into surface photochemistry on the model photocatalyst surface of rutile TiO2(110) is reviewed. In particular, scanning probe microscopy (SPM) techniques have enabled researchers to take a 'nanoscale' approach to photocatalysis that includes interrogation of the reactivities of specific sites and adsorbates on a model photocatalyst surface. The rutile TiO2 surface has become the prototypical oxide. The surface electronic structure also influences acceptor and donor levels in adsorbed species, which in turn sets the conditions for electron transfer events important in photocatalysis. In concept, SPM can provide a site-by-site assessment of both the filled and empty electronic states of a surface structure. Molecular systems are highlighted in which there is a high degree of certainty in SPM's ability to identify the reactant. These include adsorbed oxygen, CO, carboxylates, and a variety of other molecular systems.