Molybdenum Chloride Nanostructures with Giant Lattice Distortions Intercalated into Bilayer Graphene

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 MoClx 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
MoClx, 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.