In-Situ Construction of Functional Multi-Dimensional MXene-based Composites Directly from MAX Phases through Gas-Solid Reactions.

The weak bonding of A atoms with MX layers in MAX phases not only enables the selective etching of A layers for MXene preparation but brings about the chance to construct A derivatives/MXene composites via in situ conversion. Here, a facile and general gas-solid reaction systems are elegantly devised to construct multi-dimensional MXene based composites including AlF nanorods/MXene, AlF nanocrystals/MXene, amorphous AlF/MXene, A filled carbon nanotubes/MXene, layered metal chalcogenides/MXene, MOF/MXene, and so on. The intrinsic effect mechanism of interlayer confinement towards crystal growth, catalytic behavior, van der Waals-heterostructure construction and coordination reaction are rationally put forward. The tight interface combination and synergistic effect from distinct components make them promising active materials for electrochemical applications. More particularly, the AlF nanorods/NbC MXene demonstrate bi-directional catalytic activity toward the conversion between LiS and lithium polysulfides, which alleviates the shuttle effect in lithium-sulfur batteries.