Direct Synthesis of Carbon–Molybdenum Carbide Nanosheet Composites via a Pseudotopotactic Solid-State Reaction

We report the solid-state reaction of MoO₂ nanosheets, obtained from the soft-chemical delamination of Na_0.9Mo₂O₄, into metallic Mo₂C single layers that constitute a new family of versatile carbide nanosheets. This so-called pseudotopotactic reaction, i.e., conversion from nanosheet to nanosheet, is aided by the use of cationic polymers as binders for the film growth based on electrostatic self-assembly. Compared to Mo₂C in the bulk form, 2D anisotropic Mo₂C sheets having a larger surface-area-to-volume ratio are of significant use in potential electrochemical applications, and it is also worth noting that the thickness of Mo₂C sheets can be controlled in the nanometer range by altering the stacking number of the precursor nanosheets