Cu Intercalation-Stabilized 1T′ MoS₂ with Electrical Insulating Behavior

The intercalated two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted much attention for their designable structures and novel properties. Among this family, host materials with low symmetry such as 1T' phase TMDCs are particularly interesting because of their potentials in inducing unconventional phenomena. However, such systems typically have low quality and poor stability, hindering further study of the structure-property relationship and applications. In this work, we intercalated Cu into 1T' MoS₂ with high crystallinity and high thermal stability up to ∼300 °C. We identified the distribution and arrangement of Cu intercalators for the first time, and the results show that Cu intercalators occupy partially the tetrahedral interstices aligned with Mo sites. The obtained Cu-1T' MoS₂ exhibits an insulating hopping transport behavior with a large temperature coefficient of resistance reaching -4∼-2%·K^-1. This work broadens the artificial intercalated structure library and promotes the structure design and property modulation of layered materials.