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Open Access Research Article Just Accepted
Layered metal carbo-selenide Nb2CSe2 with van der Waals interlayer coupling
Journal of Advanced Ceramics
Available online: 25 November 2024
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The stacking structure of Nb2CSe2, a newly synthesized layered metal carbo-selenide, is elucidated by scanning transmission electron microscopy. Nb2CSe2 features Se-Nb-C-Nb-Se quintuple atomic layers. These layers stacked in Bernal mode. According to the mode, Nb2CSe2 crystallizes in a trigonal symmetry (space group P3(_)m1, No. 164), with lattice parameters of a = 3.33 Å, and c = 18.20 Å. Electronic structure calculations indicate that the metal carbo-selenide has Fermi energy crossing the bands where they touch to give a zero gap, showing it is an electronic conductor. As evidenced experimentally, the electrical conductivity is as high as 6.6 ´ 105 S m-1, outperforming the counterparts in the MXene family. Due to the layered structure, the bonding in Nb2CSe2 with an ionic formula of (Nb1.48+)2(C1.74-)(Se0.61-)2 is highly anisotropic with metallic–covalent–ionic bonding in intralayers while weak bonding between interlayers. The layered nature is further evidenced by elastic properties, interlayer energy, and friction coefficient determination. These characteristics recognize that Nb2CSe2 is exactly the analogue of MoS2 that is the typical binary van der Waals solid (vdW). Moreover, vibrational properties are reported, which may offer an optical identification standard to the new ternary vdW solid in spectroscopic studies including Raman scattering and infra-red absorption.

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