| AVS 65th International Symposium & Exhibition | |
| Fundamental Discoveries in Heterogeneous Catalysis Focus Topic | Tuesday Sessions |
| Session HC+SS-TuA |
| Session: | A Tale of Two Scales: Catalytic Processes and Surface Science |
| Presenter: | Si Woo Lee, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea |
| Authors: | S.W. Lee, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea S. Lee, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea H. Lee, Institute for Basic Science (IBS), Republic of Korea W. Park, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea Y. Jung, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea J.Y. Park, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea |
| Correspondent: | Click to Email |
Nonadiabatic electronic excitation in exothermic chemical reactions leads to the flow of energetic electrons with an energy of 1-3 eV which is called “hot electrons”. Direct detection of hot electron flow and observation of its role in catalytic reactions are important for understanding metal-oxide heterogeneous catalysis [1, 2]. Using Pt/n-type TiO2 Schottky nanodiode, we show the production of hot electron flow generated by methanol oxidation (Pmethanol 4 Torr and Poxygen at 760 Torr) on Pt thin film, and detect as steady-state hot electron current (chemicurrent) which is generated by exothermic chemical reactions on Pt catalyst surface. Under methanol oxidation, methanol can be converted to CO2 by full oxidation or methyl formate by partial oxidation of methanol. We show that the activation energy of chemicurrent is quite close to that of turnover frequency, indicating that the chemicurrent was originated from the catalytic reaction on Pt thin film. In addition, the dependence of the partial pressure on the chemicurrent was investigated by varying partial pressure of methanol (1-4 Torr). The result shows that the selectivity toward methyl formate formation is well correlated with the chemicurrent. For fundamental understanding of correlation between selectivity and chemicurrent, we carried out the DFT calculation on the thermodynamic energy for each step, and found that the energy gain for partial oxidation reaction was higher than that of the full oxidation reaction, which is responsible for the higher flux of hot electron under methyl formate formation. We discuss the role of metal-oxide interfaces in determining the catalytic selectivity and chemicurrent yield.
Reference
1. Park, J. Y.; Baker, L. R.; Somorjai, G. A., Role of Hot Electrons and Metal–Oxide Interfaces in Surface Chemistry and Catalytic Reactions. Chem. Rev. 2015, 115 (8), 2781-2817.
2. Park, J. Y.; Kim, S. M.; Lee, H.; Nedrygailov, I. I., Hot-Electron-Mediated Surface Chemistry: Toward Electronic Control of Catalytic Activity. Acc. Chem. Res. 2015, 48 (8), 2475-2483.