Electrical Engineering of the Oxygen Adatom and Vacancy on Rutile TiO₂(110) by Atomic Force Microscopy at 78 K

Controllable manipulation of the chemisorbed adsorbates and surface defects on transition metal oxides may provide an efficient means of improving the efficiency of catalytic reactions. Electrically induced atom/molecule manipulation has been repeatedly demonstrated on metal and insulating films but not sufficiently on semiconductors. Here, we demonstrate that the oxygen adatom and vacancy on rutile TiO₂(110)-(1 × 1) can be electrically manipulated using the tip of a non-contact atomic force microscopy in a completely controllable, reversible, and unprecedented manner. By controlling the polarity, magnitude and site of the voltage pulse, the oxygen adatom can be manipulated controllably without any charge state or conformational change. In addition, the oxygen vacancy can be reversibly created and healed by vertically transforming the oxygen atom between the surface and tip, and such switching bond cleavage and formation can be electrically activated by ramping the bias voltage. Based on our experimental results, such electrically induced reversible manipulation of the adsorbates and defects can be dominantly attributed to the local electric field effect automatically formed in the tunneling junction. The qualitatively unparalleled approaches introduced herein avoid the strong mechanical interaction between the tip apex and target atoms in traditional atom manipulation. This pioneering work could enable significant improvement in the catalytic efficiency of catalytic reactions initiated by atom manipulation.