11:00 〜 11:15
▼ [18a-F210-9] Measurement and manipulation of the charge state of adsorbed oxygen adatoms on rutile TiO2(110)-1 × 1 surface by nc-AFM and KPFM
キーワード：charge state, TiO2(110), Non-contact atomic force microscopy
Charge state of surface-supported adsorbates drastically governs their physical and chemical properties. In this respect, tremendous experimental and theoretical achievements have been made in investigating the charge state of the adsorbates. Among these works, noncontact atomic force microscopy (nc-AFM), besides the capability of characterizing surface structural and electronic properties, has recently been exploited as a powerful tool to measure and control the charge state of the adsorbates. [1] [2] On the other hand, catalytic reactions based on oxygen-rich titanium dioxide (O-TiO2) has captured extensive research interest in recent years, and a host of experimental and theoretical works focus on the investigation of the adsorbed oxygen species. Additionally, it has been strongly suggested that the activation of the adsorbed Oad is a key factor toward the catalytic reactions, which considerably depends on its charge state. [3] However, there is precise little experimental or theoretical works about the measurement and manipulation of the charge state of the adsorbed Oad.
Here, the charge state of adsorbed oxygen adatoms (Oad) on rutile TiO2(110)-1 × 1 surface is successfully measured and manipulated by a combination of nc-AFM and Kelvin probe force microscopy (KPFM) at 78 K. In this work, the assigned superoxo (Oad-, 2Oad-) and peroxo (Oad2-, 2Oad2-) oxygen species shown in Figure 1(a) are clearly distinguished in AFM and KPFM images depending on the strong image contrast with atomic resolution, which is also supported by the measurement of short-range force (FSR) and local contact potential difference (VLCPD) as a function of tip-sample distance. Besides that, the charge state of Oad can be stepwise switched between superoxo and peroxo state by decreasing the tip-sample distance, which is attributed to the gradually enhanced tip-induced electric field. This work provides a novel route for the investigation of the charge state of the adsorbates and open up a prospect for the studies of transition metal oxide based catalytic reactions.
Here, the charge state of adsorbed oxygen adatoms (Oad) on rutile TiO2(110)-1 × 1 surface is successfully measured and manipulated by a combination of nc-AFM and Kelvin probe force microscopy (KPFM) at 78 K. In this work, the assigned superoxo (Oad-, 2Oad-) and peroxo (Oad2-, 2Oad2-) oxygen species shown in Figure 1(a) are clearly distinguished in AFM and KPFM images depending on the strong image contrast with atomic resolution, which is also supported by the measurement of short-range force (FSR) and local contact potential difference (VLCPD) as a function of tip-sample distance. Besides that, the charge state of Oad can be stepwise switched between superoxo and peroxo state by decreasing the tip-sample distance, which is attributed to the gradually enhanced tip-induced electric field. This work provides a novel route for the investigation of the charge state of the adsorbates and open up a prospect for the studies of transition metal oxide based catalytic reactions.