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Sulfur vacancies (SVs) inherent in MoS2 are generally detrimental for carrier mobility and optical properties. Thiol chemistry has been explored for SV repair and surface functionalization. However, the resultant products and reaction mechanisms are still controversial. Herein, a comprehensive understanding on the reactions is provided by tracking potential energy surfaces and kinetic studies. The reactions are dominated by two competitive mechanisms that lead to either functionalization products or repair SVs, and the polarization effect from decorating thiol molecules and thermal effect are two determining factors. Electron-donating groups are conducive to the repairing reaction whereas electron-withdrawing groups facilitate the functionalization process. Moreover, the predominant reaction mechanism can be switched by increasing the temperature. This study fosters a way of precisely tailoring the electronic and optical properties of MoS2 by means of thiol chemistry approaches. [ABSTRACT FROM AUTHOR]

Potential energy curves (PECs) for the first three dissociation channels of [Be–Xe] + have been calculated at the MRCI level of theory with Davidson and relativistic correction. Spin–orbit coupling is considered by the state interaction approach using the full Breit-Pauli Hamiltonian to analyze the interactions between Σ and Π electronic states in PECs crossing regions. Curves avoided crossings must be considered for A 2 Π and 2 2 Π, 2 2 Σ + and 3 2 Σ + states to accurately estimate of spectroscopic parameters. Based on the PECs, spectroscopic parameters are determined. Finally, the transition dipole moments and radiative lifetimes of all possible transitions are predicted for future laboratory researches. [ABSTRACT FROM AUTHOR]