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 Na0.9Mo2O4, 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.