Deposition of porous few-layer WSe2 flakes with high density of exposed edge sites

In this study, remarkably differing to reported well-defined triangular WSe2 flakes, porous WSe2 flakes with large amount of holes were deposited using graphene quantum dots(GQDs) as promoters. By employing this method, triangular or circular thorough holes can be efficiently deposited on basal plane of WSe2 flakes. The size of holes and density of edges vary with layer number of WSe2 basal plane. Highest density of edges emerges on 4-layer WSe2 flake, which is greatly enhanced by 580% compared to those well-defined triangular 4-layer flakes. Finally we propose that the growth of holes is validated by poor wetting between WSe2 and GQDs, while the final shape is determined by crystal symmetry, diffusion and thermal dynamics.