Formation of graphene nanostructures using laser induced vaporization of entrapped water

Facile construction of graphene nanostructures are potentially important for fundamental studies and various applications owing to its transparency and mechanical strength. Here we found that focused laser irradiation of a graphene/entrapped water/hydrophobic substrate leads to vaporization of entrapped water and consequent formation of graphene nanostructures. Graphene mechanically exfoliated on a hydrophobicized Si substrate was served as a transformable and impermeable nanocontainer in which water anisotropically and slowly diffuses from the weak edges into the van der Waals (vdW)-coupled interstitial volume between graphene and the substrate. Time-lapsed Raman mappings show that water entrapment promotes progressive lowering of the frequencies of the G and 2D bands of graphene and exhibits slower diffusion owing to vdW decoupling of substrate-induced doping and biaxial strain of graphene with hydrophobic substrate. Moreover, vaporized entrapped water promotes nanostructures by graphene sliding and bulging actions. This methodology represents viable approach to produce nanostructures from two dimensional materials.