Hydrogen‐induced sulfur vacancies on the MoS2 basal plane studied by AP‐XPS and DFT calculations
Fumihiko Ozaki, Shunsuke Tanaka, YoungHyun Choi, Wataru Osada, Kozo Mukai, Mitsuaki Kawamura, Masahiro Fukuda, Masafumi Horio, Takanori Koitaya, Susumu Yamamoto, Iwao Matsuda, Taisuke Ozaki, Jun Yoshinobu- Physical and Theoretical Chemistry
- Atomic and Molecular Physics, and Optics
Sulfur vacancy on an MoS2 basal plane plays a crucial role in device performance and catalytic activity; thus, an understanding of the electronic states of sulfur vacancies is still an important issue. We investigate the electronic states on an MoS2 basal plane during heating in hydrogen by ambient‐pressure X‐ray photoelectron spectroscopy (AP‐XPS) and density functional theory calculations. The present AP‐XPS results show a decrease in the intensity ratio of S 2p to Mo 3d, indicating that sulfur vacancies are formed. 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. The calculated shifts for Mo 3d and S 2p with the formation of sulfur vacancy are consistent with the experimentally observed binding energy shifts. Mulliken charge analysis indicates that this is caused by an increase in the amount of electrons in Mo and S atoms around the sulfur vacancy compared to the pristine surface. The present investigation provides a guideline for sulfur vacancy engineering.