Associate Professor Yanjun Li 's research team at the Department of Applied Physics at the Graduate School of Engineering at Osaka University, which includes Graduate Student Yuuki Adachi (currently a PD of the Graduate School of Frontier Sciences at the University of Tokyo, Graduate Student Qiang Zhu, Dr. Huanfei Wen, and Professor Yasuhiro Sugawara, has collaborated with Professor Ivan Stich's research team of the Institute of Physics at the Slovak Academy of Sciences, which includes Researchers Ján Brndiar, Martin Konôpka, and Robert Turanský, together with Professor Lev Kantorovich of King's College London, UK, and have used atomic force microscopy (AFM) to study the probe-activated single-atom catalytic reaction on the surface of TiO2 (rutile). Specifically, they studied CO oxidation reaction by Au adatoms on a rutile surface. Their study results were published in the online edition of Science Advances.
Monatomic catalysis of CO oxidation on metal oxide surfaces is extremely important in greenhouse gas recycling and automotive catalysis, but the mechanism at the atomic scale is not yet understood. Using scanning probe microscopy, the research group showed that charging single Au atoms on a TiO2 surface with both positive and negative charges significantly enhanced CO adsorption. Furthermore, no adsorption of CO was observed on neutral Au atoms. Two different CO adsorption geometries on Au atoms were also identified.
The research group demonstrated that the redox state of adsorbed Au monoatoms, CO adsorption geometry, and CO adsorption and desorption by the AFM probe could be completely controlled. The probe activated the Eley−Rideal oxidation reaction between CO and adjacent oxygen atoms on a charged Au atom.
The results provide unprecedented control over and insight into CO adsorption and suggest that the activity after electron or hole injection into Au atoms is also an important factor in photocatalysis under realistic conditions. The research group will use AFM in the future to clarify the activation source of CO oxidation at the atomic level under realistic catalytic reaction conditions.
Publication: Science Advances
Title: Tip-activated single-atom catalysis: CO oxidation on Au adatom on oxidized rutile TiO2 surface
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