Exploring the nature of hydrogen of Rutile TiO2(110) at 78 K

Abstract The hydrogen on the surface or in the subsurface of rutile TiO2 play an important role in the surface chemical reactions and understanding the catalytic reactions due to its excess electrons. In this work, we have systematically explored the nature of hydrogen atom by atomic force microscopy (AFM)/scanning tunneling microscopy (STM) and investigated the behaviors and mechanism of hydrogen atom desorption and transfer between the surface and subsurface by Kelvin probe force spectroscopy (KPFS). The atomic contrast of surface hydrogen (Hsurf) and subsurface hydrogen (Hsub) are clearly identified by dynamic and static STM. The Hsub-Hsub interactions are systematically investigated, demonstrating the unusual no-repulsive effect of species with the same polarity. Importantly, the reversible hydrogen atom transfer between the sample surface and subsurface was successfully manipulated by KPFS performance, and mechanism of hydrogen transfer proceeds was proposed that force field together with electric field between the tip-sample space reduce the height and width of barrier resulting in the hydrogen atom transfer. The present study is expected to provide some new insights into the nature and manipulation of hydrogen atom and is useful to design the new catalyst of metal oxide.