Nearly free electron states in MXenes

By Mohammad Khazaei, A. Ranjbar, M. Ghorbani‐Asl, M. Arai, Taizo Sasaki, Yunye Liang, Seiji Yunoki. 2016

180 citations recorded by the source corpus.

Using a set of first-principles calculations, we studied the electronic structures of two-dimensional transition metal carbides and nitrides, so called MXenes, functionalized with F, O, and OH. Our projected band structures and electron localization function analyses reveal the existence of nearly free electron (NFE) states in a variety of MXenes. The NFE states are spatially located just outside the atomic structure of MXenes and are extended parallel to the surfaces. Moreover, we found that the OH-terminated MXenes offer the NFE states energetically close to the Fermi level. In particular, the NFE states in some of the OH-terminated MXenes, such as $\mathrm{T}{\mathrm{i}}_{2}\mathrm{C}{(\mathrm{OH})}_{2},\mathrm{Z}{\mathrm{r}}_{2}\mathrm{C}{(\mathrm{OH})}_{2},\mathrm{Z}{\mathrm{r}}_{2}\mathrm{N}{(\mathrm{OH})}_{2},\mathrm{H}{\mathrm{f}}_{2}\mathrm{C}{(\mathrm{OH})}_{2},\mathrm{H}{\mathrm{f}}_{2}\mathrm{N}{(\mathrm{OH})}_{2},\mathrm{N}{\mathrm{b}}_{2}\mathrm{C}{(\mathrm{OH})}_{2}$, and $\mathrm{T}{\mathrm{a}}_{2}\mathrm{C}{(\mathrm{OH})}_{2}$, are partially occupied. This is in remarkable contrast to graphene, graphane, and $\mathrm{Mo}{\mathrm{S}}_{2}$, in which their NFE states are located far above the Fermi level and thus they are unoccupied. As a prototype of such systems, we investigated the electron transport properties of $\mathrm{H}{\mathrm{f}}_{2}\mathrm{C}{(\mathrm{OH})}_{2}$ and found that the NFE states in $\mathrm{H}{\mathrm{f}}_{2}\mathrm{C}{(\mathrm{OH})}_{2}$ provide almost perfect transmission channels without nuclear scattering for electron transport. Our results indicate that these systems might find applications in nanoelectronic devices. Our findings provide new insights into the unique electronic band structures of MXenes.

Subfields: Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/95db27212ba4ced1a8acb5044013a2e06e1896a7

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In Materials Chemistry

Citations in the corpus

MXetronics: Electronic and photonic applications of MXenes (2019, background): “partially occupied and located near Fermi level.[69] (Figure 4(d) and (e)) This implies that”
Recent advances in MXenes: From fundamentals to applications (2019, background): “, layered materials such as metal oxides and graphene have been extensively studied as gas sensors. MXenes have also been shown to be potential gas sensors due to the direct charge transfer mechanism [94]. Recent experiments have observed that T 3C 2 exhibits anity towards CO 2 capture selectivity o”