Dopant-sheet interaction and its role in the enhanced chemical activity of doped MoTe2

Abstract

The present work investigates, employing density functional theory (DFT) computations, the impact of doping on the chemical activity of monolayer MoTe2, and the role of dopant-sheet interaction on the effect. In the employed doping model, the X atoms (Ga, Ge, As, Se, and Br) adsorb in Te vacancies of the sheet at a ∼3% concentration. The results predict that, for all investigated elements, the doping is energetically favorable in conditions rich in Te and X. In the case of Ga (group 13) and Ge (group 14), a lower number of valence electrons gives rise to a mixed sp2/sp3 hybridization to facilitate a trigonal pyramidal bonding geometry with neighboring Mo. In contrast, the remaining elements (groups 15–17) adopt a hybridization with a stronger sp3 character. However, due to their valence configuration, the Mo−X bonding promotes a different charge distribution near the dopant. Hence, the dopant-sheet interaction has a significant impact on the chemical activity of MoTe2. The results predict that, except Se, all dopants enhance the adsorption energy and charge transfer for molecules of Cl2. Furthermore, for Ga and Ge, the X−Cl interaction facilitates the dissociation of the molecule. In contrast, Se has a limited impact on the adsorption as the element promotes the same bonding configuration as Te in the pristine sheet.