Enhanced 1T'-Phase Stabilization and Chemical Reactivity in a MoTe2 Monolayer through Contact with a 2D Ca2 N Electride.

Among the widely studied 2D transition metal dichalcogenides (TMDs), MoTe2 has attracted special interest for phase-change applications due to its small 2H-1T' energy difference, yet a large scale phase transition without structural disruption remains a significant challenge. Recently, an interesting long-range phase engineering of MoTe2 has been realized experimentally by Ca2 N electride. However, the interface formed between them has not been well understood, and moreover, it remains elusive how the presence of Ca2 N would affect the basal plane reactivity of MoTe2 . To address this, we performed density functional theory (DFT) calculations to investigate the potential of tuning the phase stability and chemical reactivity of a MoTe2 monolayer via interacting with Ca2 N to form a van der Walls heterostructure. We found that the contact nature at the 2H-MoTe2 /Ca2 N interface is Schottky-barrier-free, allowing for the spontaneous electron transfer from Ca2 N to 2H-MoTe2 to make it strongly n-type doped. Moreover, Ca2 N doping significantly lowers the energy of 1T'-MoTe2 and dynamically triggers the 2H-to-1T' transformation. The Ca2 N-induced phase modulation can also be applied to tune the phase energetics of MoS2 and MoSe2 . Furthermore, using H adsorption as the testing ground, we also find that the H binding on the basal plane of MoTe2 is enhanced after forming heterostructure with Ca2 N, potentially providing basis for surface modification and other related catalytic applications.