Investigations on the wettability of graphene on a micron-scale hole array substrate

In this work, graphene grown by chemical vapour deposition is transferred onto a micron-scale hole array (MSHA) substrate by a polymer-free transfer process. The graphene adheres to the walls of the microholes and complies with the morphologies of the micronscale hole substrate. In contrast to previous reports of the partial-transparency of the wettability of graphene on a plane substrate, the wettability of graphene on a micro-scale hole array substrate is found to be hydrophobic with a contact angle of 93.1 degrees. This is quite different from that of graphene on a planar SiO2/Si substrate, which is hydrophilic with a contact angle of 83.0 degrees. We find that a micron-scale hole array substrate has a regulation effect on the wettability of graphene when the graphene almost completely complies with the morphology of the micron-scale hole array substrate surface and the change from hydrophilic to hydrophobic provides a guide for designing surfaces with controllable wettability.