Surface defects engineering and reactivity towards methanol decomposition of layered PtTe₂

Jing-Wen Hsueh^1*, Lai-Hsiang Kuo¹, Wan-Hsin Chen², Chia-Nung Kuo³, Yu-Ling Lai⁴, Li-Chung Yu⁴, Hung-Wei Shiu⁴, Yao-Jane Hsu⁴, Chin-Shan Lue³, Chun-Liang Lin², Meng-Fan Luo¹

¹Department of Physics, National Central University, Taoyuan, Taiwan
²Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
³Department of Physics, National Cheng-Kung University, Tainan, Taiwan
⁴National Synchrotron Radiation Research center, Hsinchu, Taiwan

* Presenter:Jing-Wen Hsueh, email:az11861124@gmail.com

Layered transition metal dichalcogenides (TMDs) have attracted considerable interests due to their potential usage as alternative catalysts. However, the limited density of active sites (typically edge sites or surface defects) is a significant challenge to increase surface reactivity. In this study, we show that the reactivity of the PtTe₂ basal plane is enhanced by introducing surface Te-vacancies, corresponding to under-coordinated surface Pt (Pt_uc), and the defect density can be controlled with Argon ion (Ar⁺) bombardment. With the reflection high energy electron diffraction (RHEED) and the photoelectron spectroscopy (PES), we demonstrate the surface structure and the chemical state are both dramatically changed after the Ar⁺ bombardment whereas the surface structure was restored after the annealing at 720 K for an hour. The PES spectra of Pt 4f indicate the emergence of Pt_uc, reflecting the production of Te vacancies and that the number of Pt_uc was increased almost in linear proportion with the Ar⁺ bombardment time. Our results also show a highly positive correlation between the numbers of decomposed methanol and Pt_uc and thus indicate that Pt_uc is an active site and the surface reactivity can be manipulated by controlling the number of Pt_uc through the Ar⁺ bombardment treatment.

Keywords: PtTe2, Transition metal dichalcogenides, Methanol decomposition, Surface defects engineering , Photoelectron spectroscopy