In my talk, I will introduce our recent researches including of Cu(110)-O surface, TiO₂(110) surface. In TiO₂(110) study, I will focus on the research of charge state and charge manipulation. The catalytic mechanism of TiO₂ surface fascinated us for long time because of the unrevealing reaction mechanism in ambient condition. A key challenge is to reveal these mechanism at atomic scale under specific gas phase [1, 2]. Charge state of surface-supported adsorbates drastically governs their physical and chemical properties [3].The 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. The activation of the adsorbed O_ad is a key factor toward the catalytic reactions. Therefore, it is important to measure and manipulate the charge state of the adsorbed O_ad by experimental and theoretical works.

The charge state of adsorbed O_ad on rutile TiO₂(110) surface has been measured and manipulated by non-contact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM) at 78 K [4,5]. The oxygen species of assigned O_ad^δ-, 2O_ad^δ-, O_ad ^(δ+∆δ)- and 2O_ad ^(δ+∆δ)- are clearly distinguished in AFM and KPFM images with atomic resolution. Besides that, the charge state of O_ad can be stepwise switched between 2O_ad^δ- and 2O_ad ^(δ+∆δ)- states by controlling the polarity of voltage pulse, which is attributed to the effect of tunneling current. This work provides a novel route for investigation of the charge state of the adsorbates and opens up a prospect for studies of transition metal oxide based catalytic reactions.

In my talk, I will introduce our group and our home-built instruments of NC-AFM at 4K, magnetic resonance force microscopy (MRFM), and high-speed AFM in liquid at room temperature. 

References:

[1] E. Arima, H. F. Wen, Y. Naitoh, Y. J. Li and Y. Sugawara, Nanotechnology, 29, 105504, (2018).

[2] H. F. Wen, Y. Adachi, Y. J. Li, Y. Sugawara, Phys. Chem. Chem. Phys. 20, 28331 (2018).

[3] L. Gross, F.Mohn, P. Liljeroth, J. Repp, F. J.Giessibl, G. Meyer, Science, 324, 1428 (2009)

[4] Q. Z. Zhang, Y. J. Li, H. F. Wen, Y. Adachi, Y. Sugawara, R. Xu, Z. H. Cheng, J. Brndiar, L. Kantorovich, and I. Štich, J. Am. Chem. Soc., 140 (46), 15668 (2018). 

[5] Y. Adachi, H. F. Wen, Q. Z. Zhang, M. Miyazaki, Y. Sugawara, H. Q. Sang, J. Brndiar, L. Kantorovich, I. Štich, Y. J. Li, ACS Nano (2019).

Recently 5 years, she was the 27 projects leader and 4 projects subleader of Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. She was a six international projects leader with China, UK and Slovakia. She was one of key person to evaluate JSPS research fee in Japan. Her lab has 7 PhD students, 4 master students, 2 undergraduate students and 1 research student.

Yanjun Li has got her MEng (Master) and Ph.D. Eng degrees from University of Tsukuba, Japan in 1998 and 2001. After that, she was a Research Fellow at Institute for Molecular Science, Okazak National Research Institute, Japan. From 2004, she worked as Visiting Associate Professpr at Osaka University, Japan and from 2010-present she is an Associate Professpr at Osaka. She has published more than 120 papers in peer-reviewed scientific journals. From 2010, she is professor at North University of China and one of 100 experts in Shanxi province. From 2010 to 2011, she is Visiting Professor at Yale University, USA. 

Her research involves using various forms of scanning probe microscopy (SPM), such as atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM), to investigate physical and chemical properties and explore and elucidate new physical phenomena on solid surfaces. Her group is working to elucidate the mechanisms of catalytic reactions on noble metal-supported metal oxide surfaces at the atomic level.