Imaging oxygen molecular adsorption and dissociation on the Ti site of rutile TiO 2 (110) surface with real configuration at 78 K by atomic force microscopy

• Published in: Physical chemistry chemical physics : PCCP 2020-09, Vol.22 (35), p.19795-19801
• Main Authors: Wen, Huan Fei, Sang, Hongqian, Sugawara, Yasuhiro, Li, Yan Jun
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/D0CP03549A

Understanding oxygen adsorption and dissociation on the five-fold coordinated titanium (Ti 5c ) site of the rutile TiO 2 surface is important in clarifying chemical reaction processes. Accordingly, three different configurations of molecularly adsorbed O 2 , including parallel side-on, inclined side-on and end-on configurations, and their dissociation were directly observed with atomic resolution at 78 K by atomic force microscopy. Our results experimentally demonstrated that the three adsorbed O 2 configurations could be changed by electric field stimulation. The initial configurations of the adsorbed O 2 and transition of O 2 configurations were related to their coverage. On the other hand, the tunneling current stimulation could dissociate these O 2 species, indicating that they are precursors for the O adatom (O ad ). It is proposed that the effect of electric field stimulation contributes to the transition of these three adsorbed O 2 configurations, and the effect of the tunneling current is the main factor for the dissociation of the adsorbed O 2 . In addition, based on the atomic contrast and height histograms of O ad , different charge states of O ad were observed, which could coexist on the surface region. The present study demonstrates an intuitional observation of O 2 adsorption and dissociation on the Ti 5c site, and thus is expected to be useful to understand the surface reactions on the oxide surface.