When van der Waals\nMet Kagome: A 2D Antimonide with\na Vanadium-Kagome Network

2D materials showcase unconventional properties emerging\nfrom quantum\nconfinement effects. In this work, a “soft chemical”\nroute allows for the deintercalation of K<sup>+</sup> from the layered\nantimonide KV<sub>6</sub>Sb<sub>6</sub>, resulting in the discovery\nof a new metastable 2D-Kagome antimonide K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> with a van der Waals gap of 3.2 Å. The structure\nof K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> was determined via\nthe synergistic techniques, including X-ray pair distribution function\nanalysis, advanced transmission electron microscopy, and density functional\ntheory calculations. The K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> compound crystallizes in the monoclinic space group <i>C</i>2/<i>m</i> (<i>a</i> = 9.57(2) Å, <i>b</i> = 5.502(8) Å, <i>c</i> = 10.23(2) Å,\nβ = 97.6(2)°, <i>Z</i> = 2). The [V<sub>6</sub>Sb<sub>6</sub>] layers in K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> are retained upon deintercalation and closely resemble the layers\nin the parent compound, yet deintercalation results in a relative\nshift of the adjacent [V<sub>6</sub>Sb<sub>6</sub>] layers. The magnetic\nproperties of the K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> phase\nin the 2–300 K range are comparable to those of KV<sub>6</sub>Sb<sub>6</sub> and another Kagome antimonide KV<sub>3</sub>Sb<sub>5</sub>, consistent with nearly temperature-independent paramagnetism.\nElectronic band structure calculation suggests a nontrivial band topology\nwith flat bands and opening of band crossing afforded by deintercalation.\nTransport property measurements reveal a metallic nature for K<sub>0.1(1)</sub>V<sub>6</sub>Sb<sub>6</sub> and a low thermal conductivity\nof 0.6 W K<sup>–1</sup> m<sup>–1</sup> at 300 K. Additionally,\nion exchange in KV<sub>6</sub>Sb<sub>6</sub> via a solvothermal route\nleads to a successful partial exchange of K<sup>+</sup> with <i>A</i><sup>+</sup> (<i>A</i> = Na, Rb, and Cs). This\nstudy highlights the tunability of the layered structure of the KV<sub>6</sub>Sb<sub>6</sub> compound, providing a rich playground for the\nrealization of new 2D materials.