Spontaneous self-intercalation of copper atoms into transition metal dichalcogenides

Xiao-Chen Liu; Shuyang Zhao; Xueping Sun; Liangzi Deng; Xiaolong Zou; Youcheng Hu; Yun-Xiao Wang; Ching-Wu Chu; Jia Li; Jingjie Wu; Fu-Sheng Ke; Pulickel M Ajayan

doi:10.1126/sciadv.aay4092

Spontaneous self-intercalation of copper atoms into transition metal dichalcogenides

Sci Adv. 2020 Feb 14;6(7):eaay4092. doi: 10.1126/sciadv.aay4092. eCollection 2020 Feb.

Authors

Xiao-Chen Liu¹, Shuyang Zhao², Xueping Sun³, Liangzi Deng⁴, Xiaolong Zou⁵, Youcheng Hu¹, Yun-Xiao Wang¹, Ching-Wu Chu^{4

6}, Jia Li², Jingjie Wu^{7

8}, Fu-Sheng Ke¹, Pulickel M Ajayan⁸

Affiliations

¹ Sauvage Center for Molecular Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
² Laboratory for Computational Materials Engineering, Division of Energy and Environment, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
³ School of Materials Science and Engineering, HuaZhong University of Science and Technology, Wuhan, Hubei 430074, China.
⁴ Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204-5005, USA.
⁵ Shenzhen Geim Graphene Center and Low-Dimensional Materials and Devices Laboratory, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen 518055, China.
⁶ Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁷ Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA.
⁸ Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005, USA.

Abstract

Intercalated transition metal dichalcogenides (TMDs) have attracted substantial interest due to their exciting electronic properties. Here, we report a unique approach where copper (Cu) atoms from bulk Cu solid intercalate spontaneously into van der Waals (vdW) gaps of group IV and V layered TMDs at room temperature and atmospheric pressure. This distinctive phenomenon is used to develop a strategy to synthesize Cu species-intercalated layered TMD compounds. A series of Cu-intercalated 2H-NbS₂ compounds were obtained with homogeneous distribution of Cu intercalates in the form of monovalent Cu (I), occupying the tetrahedral sites coordinated by S atoms within the interlayer space of NbS₂. The Fermi level of NbS₂ shifts up because of the intercalation of Cu, resulting in the improvement of electrical conductivity in the z-direction. On the other hand, intercalation of Cu into vdW gaps of NbS₂ systematically suppresses the superconducting transition temperature (T _c) and superconducting volume fraction.

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