In this study, a comprehensive investigation of the role of sulfur vacancies on the electronic structure and surface reactivity of molybdenum disulfide is presented. A 2H-MoS2 single crystal was annealed at two different temperatures, namely, 300 and 500 degrees C in vacuum, in order to generate sulfur vacancies in a controlled manner. The detailed characterization of the electronic structure by means of X-ray and ultraviolet photoelectron spectroscopy clearly evidences the formation of a strong surface dipole as well as surface band bending due to the excess of negative charge on the Mo centers, as a consequence of the generated sulfur vacancies. After thermal treatment, a mercaptoundecylphosphonic acid molecule, which consists of a thiol (S-H) tail group and a phosphonic acid group on the other end, was covalently attached on the surface through wet chemical functionalization in order to refill the sulfur vacancies. As a consequence of the vacancy refilling, the surface band bending is reversed and the surface dipole is remarkably decreased, being close to the initial value of the pristine surface.

Unravelling Work Function Contributions and Their Engineering in 2H-MoS2 Single Crystal Discovered by Molecular Probe Interaction / Ghiami, A; Timpel, M; Nardi, Mv; Chiappini, A; Nozar, P; Quaranta, A; Verucchi, R. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - 124:12(2020), pp. 6732-6740. [10.1021/acs.jpcc.0c00733]

Unravelling Work Function Contributions and Their Engineering in 2H-MoS2 Single Crystal Discovered by Molecular Probe Interaction

Timpel, M;Nardi, MV;Chiappini, A;Quaranta, A;
2020-01-01

Abstract

In this study, a comprehensive investigation of the role of sulfur vacancies on the electronic structure and surface reactivity of molybdenum disulfide is presented. A 2H-MoS2 single crystal was annealed at two different temperatures, namely, 300 and 500 degrees C in vacuum, in order to generate sulfur vacancies in a controlled manner. The detailed characterization of the electronic structure by means of X-ray and ultraviolet photoelectron spectroscopy clearly evidences the formation of a strong surface dipole as well as surface band bending due to the excess of negative charge on the Mo centers, as a consequence of the generated sulfur vacancies. After thermal treatment, a mercaptoundecylphosphonic acid molecule, which consists of a thiol (S-H) tail group and a phosphonic acid group on the other end, was covalently attached on the surface through wet chemical functionalization in order to refill the sulfur vacancies. As a consequence of the vacancy refilling, the surface band bending is reversed and the surface dipole is remarkably decreased, being close to the initial value of the pristine surface.
2020
12
Ghiami, A; Timpel, M; Nardi, Mv; Chiappini, A; Nozar, P; Quaranta, A; Verucchi, R
Unravelling Work Function Contributions and Their Engineering in 2H-MoS2 Single Crystal Discovered by Molecular Probe Interaction / Ghiami, A; Timpel, M; Nardi, Mv; Chiappini, A; Nozar, P; Quaranta, A; Verucchi, R. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - 124:12(2020), pp. 6732-6740. [10.1021/acs.jpcc.0c00733]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/320717
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