Identification of Atomic Defects and Adsorbate on Rutile TiO₂(110)-(1 × 1) Surface by Atomic Force Microscopy

Atomic force microscopy (AFM) has been developed as a powerful tool to study surface topography and surface chemistry with atomic resolution, whereas straightforward identification of surface point defect/adsorbate is far from trivial in AFM imaging due to its complex mechanism. In this work, we successfully demonstrate a reliable way to discriminate surface point defect/adsorbate on a rutile TiO₂ surface by AFM. Each surface point defect/adsorbate can positively respond to the applied bias voltage, but the specific response value is different. The present methodology is reliable to distinguish the surface atomic defect and adsorbates on metal oxides, no matter what kinds of tip apex termination, and useful for continuous investigation of catalytic reactions on the surface.