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The layer-dependent properties are still unclarified in two-dimensional (2D) vertical heterostructures. In this study, we layer-by-layer deposited semimetal β-In2Se3 on monolayer MoS2 to form vertical β-In2Se3/MoS2 heterostructures by chemical vapor deposition. The defect-mediated nucleation mechanism induces β-In2Se3 nanosheets to grow on monolayer MoS2, and the layer number of stacked β-In2Se3 can be precisely regulated from 1 layer (L) to 13 L by prolonging the growth time. The β-In2Se3/MoS2 heterostructures reveal tunable type-Ⅱ band alignment arrangement by altering the layer number of β-In2Se3, which optimizes the internal electron transfer. Meanwhile, the edge atomic structure of β-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch (~ 29%), and the presence of β-In2Se3 also further increases the electrical conductivity of β-In2Se3/MoS2 heterostructures. Attributed to abundant layer-dependent edge active sites, edge reconstruction, improved hydrophilicity, and high electrical conductivity of β-In2Se3/MoS2 heterostructures, the edge of β-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance. Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-L β-In2Se3. Hence, the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance.

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Publication history
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Acknowledgements

Publication history

Received: 16 April 2022
Revised: 25 June 2022
Accepted: 29 June 2022
Published: 10 August 2022
Issue date: January 2023

Copyright

© Tsinghua University Press 2022

Acknowledgements

Acknowledgements

The work was supported by the National Natural Science Foundation of China (Nos. 22175060 and 21975067) and Natural Science Foundation of Hunan Province of China (Nos. 2021JJ10014 and 2021JJ30092). X. X. X thanks to the National Science Foundation of China (No. 12104385). The computational resources were provided by the supercomputer TianHe in Changsha, China.

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