2 research outputs found
Topotactic Growth of Edge-Terminated MoS<sub>2</sub> from MoO<sub>2 </sub>Nanocrystals
Layered
transition metal dichalcogenides have distinct physicochemical
properties at their edge-terminations. The production of an abundant
density of edge structures is, however, impeded by the excess surface
energy of edges compared to basal planes and would benefit from insight
into the atomic growth mechanisms. Here, we show that edge-terminated
MoS<sub>2</sub> nanostructures can form during sulfidation of MoO<sub>2</sub> nanocrystals by using <i>in situ</i> transmission
electron microscopy (TEM). Time-resolved TEM image series reveal that
the MoO<sub>2</sub> surface can sulfide by inward progression of MoO<sub>2</sub>(202̅):MoS<sub>2</sub>(002) interfaces, resulting in
upright-oriented and edge-exposing MoS<sub>2</sub> sheets. This topotactic
growth is rationalized in the interplay with density functional theory
calculations by successive O–S exchange and Mo sublattice restructuring
steps. The analysis shows that formation of edge-terminated MoS<sub>2</sub> is energetically favorable at MoO<sub>2</sub>(110) surfaces
and provides a necessary requirement for the propensity of a specific
MoO<sub>2</sub> surface termination to form edge-terminated MoS<sub>2</sub>. Thus, the present findings should benefit the rational development
of transition metal dichalcogenide nanomaterials with abundant edge
terminations