The nanospace of the van der Waals (vdW) gap between structural units of two-dimensional (2D) materials serves as a platform for growing unusual 2D systems through intercalation and studying their properties. Various kinds of metal chlorides have previously been intercalated for tuning the properties of host layered materials, but the atomic structure of the intercalants remains still unidentified. In this study, we investigate the atomic structural transformation of molybdenum(V) chloride (MoCl₅) after intercalation into bilayer graphene (BLG). Using scanning transmission electron microscopy, we found that the intercalated material represents MoCl₃ networks, MoCl₂ chains, and Mo₅Cl₁₀ rings. Giant lattice distortions and frequent structural transitions occur in the 2D MoCl_x that have never been observed in metal chloride systems. The trend of symmetric to nonsymmetric structural transformations can cause additional charge transfer from BLG to the intercalated MoCl_x, as suggested by our density functional theory calculations. Our study deepens the understanding of the behavior of matter in the confined space of the vdW gap in BLG and provides hints at a more efficient tuning of material properties by intercalation for potential applications, including transparent conductive films, optoelectronics, and energy storage.

中文翻译：

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具有巨大晶格畸变的氯化钼纳米结构插入双层石墨烯中


二维 (2D) 材料结构单元之间的范德华 (vdW) 间隙的纳米空间可作为通过插层生长不寻常的 2D 系统并研究其特性的平台。之前已经插入了各种金属氯化物来调节主体层状材料的性能，但插入剂的原子结构仍未确定。在本研究中，我们研究了氯化钼（V）（MoCl ₅ ）嵌入双层石墨烯（BLG）后的原子结构转变。使用扫描透射电子显微镜，我们发现插层材料代表MoCl ₃网络、MoCl ₂链和Mo ₅ Cl ₁₀环。二维 MoCl _x中会发生巨大的晶格畸变和频繁的结构转变，这在金属氯化物体系中从未观察到过。正如我们的密度泛函理论计算所表明的，对称到非对称结构转变的趋势可能会导致从 BLG 到插层 MoCl _x的额外电荷转移。我们的研究加深了对 BLG 中 vdW 间隙有限空间中物质行为的理解，并为通过插层更有效地调整材料性能的潜在应用提供了线索，包括透明导电薄膜、光电子学和能量存储。