The electronic properties of MoS₂ are strongly controlled by the structure, providing a route to their modulation. We report, based on first principles calculations, that the adsorption of metal atom Cu on the surface can induce the phase transition of MoS₂ from the semiconducting 2H to the metallic 1T′ phase. Cu adsorption results in effective n-type doping of MoS₂ by charge transfer from Cu in the case of the 1T′ phase. This is distinct from the behavior in the 2H phase, where Cu does not donate any charge, and it is also distinct from alkali metal adsorption, where charge is donated to both 2H and 1T′ MoS₂. Charge donation to the 1T′ phase by Cu stabilizes it with respect to the 2H structure and importantly, it also reduces the energy barrier between the 2H and 1T′ structures. This difference reflects the higher electronegativity of Cu, which also indicates that Cu-modified MoS₂ can be expected to be less chemically reactive than MoS₂ with alkali metal adatoms. The main atomic mechanism of the structural transition is the gliding of S atoms on the upper surface. Finally, we report the energetics of the 2H to 1T′ transition with several other adatoms, Ag, Au, Ni, Pt and Pd, but none of them are as effective as Cu in inducing the transition.

中文翻译：

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铜 在MoS _2中2H–1T'跃迁的第一原理研究†

MoS ₂的电子特性受到结构的严格控制，从而提供了对其进行调制的途径。我们报告，基于第一原理计算，表面上金属原子Cu的吸附可以诱导MoS ₂从半导体2H到金属1T'相的相变。在1T'相的情况下，Cu吸附会通过Cu的电荷转移而导致MoS ₂的有效n型掺杂。这与2H相中的行为不同，在2H相中Cu不提供任何电荷，也与碱金属吸附不同，在碱金属吸附中，电荷同时提供给2H和1T'MoS ₂。Cu对1T'相的电荷捐赠使其相对于2H结构稳定，重要的是，它还减少了2H和1T'结构之间的能垒。这种差异反映了Cu的更高的电负性，这也表明与碱金属原子相比，Cu改性的MoS _2的化学反应性要比MoS _2的低。结构转变的主要原子机理是S原子在上表面滑动。最后，我们报道了从2H到1T'跃迁的能量学，以及其他几种原子，Ag，Au，Ni，Pt和Pd，但它们在诱导跃迁方面没有像Cu那样有效。