Nanowires exfoliated from one-dimensional van der Waals transition metal trihalides and quadrihalides

The exfoliation of van der Waals (vdW) materials has been widely used to fabricate two-dimensional (2D) materials. However, the exfoliation of vdW materials to isolate atomically thin nanowires (NWs) is an emerging research topic. In this letter, we identify a large class of transition metal trihalides (TMX₃), which have one-dimensional (1D) vdW structures, i.e., they comprise columns of face-sharing TMX₆ octahedral chains, whereas the chains are bound by weak vdW forces. Our calculations show that the single-chain and multiple-chain NWs constructed from these 1D vdW structures are stable. The calculated binding energies of the NWs are relatively small, suggesting that it is possible to exfoliate NWs from the 1D vdW materials. We further identify several 1D vdW transition metal quadrihalides (TMX₄) that are candidates for exfoliation. This work opens a paradigm for exfoliating NWs from 1D vdW materials.