Hydrogen-Involved Surface Processes on Model Catalysts
- PC Department Seminar
- Date: Jun 23, 2023
- Time: 11:00 AM (Local Time Germany)
- Speaker: Jun Yoshinobu
- The Institute for Solid State Physics, University of Tokyo
- Location: Building G
- Room: 2.06
- Host: Akitoshi Shiotari
The “two-step” chemical shifts of the Pd 3d5/2 binding
energy have been observed. The proposed mechanism of the hydrogen
dissociation and spillover processes includes (i) a hydrogen molecule is
dissociated at a Pd site, and the hydrogen atoms are adsorbed on the Pd
site, (ii) the number of hydrogen atoms at the Pd site increases up to
three, and (iii) the hydrogen atoms will spill over onto the Cu surface.
Systematic DFT calculations revealed the adsorption configurations
during the hydrogen adsorption and spillover processes on the Pd/Cu(111)
surface and their chemical shifts of Pd 3d.
On the other hand, by heating the MoS2 surface in hydrogen above 600 K, the present AP-XPS results show a decrease in the intensity ratio of S 2p to Mo 3d, indicating that sulfur vacancies are formed (hydrodesulfurization). Furthermore, low-energy components are observed in Mo 3d and S 2p spectra. To understand the changes in the electronic states induced by sulfur vacancy formation at the atomic scale, we calculate the core-level binding energies for the model vacancy surfaces. Mulliken charge analysis indicates that the core-level shifts are caused by an increase in the number of electrons in Mo and S atoms around the sulfur vacancy compared to the pristine surface.
 W. Osada et al., Phys. Chem. Chem. Phys., 24, 21705 (2022).
 F. Ozaki et al., Applied Surface Science, 593, 153313 (2022).
 F. Ozaki et al., to be submitted (2023).