Nanoscale water film at a super-wetting interface supports 2D material transfer

Abstract We observed a super-wetting behavior at typical chemical vapor deposition grown transition metal di-chalcogenide (TMDC) 2D material–substrate interface. Such an interface was found to keep a flat, nanoscale water film when interacting with liquid state water. Detailed in situ atomic force microscope studies found the variable thickness of the water layer. Both surfaces at the two sides of the interface, viz. the TMDC (MoS 2 or WS 2 as demonstrated) bottom surface and the exposed substrate (typically, the as-grown SiO 2 ) surface, were found to be super-wetting. This insured effectively their stable super-wetting behaviors. We further verified a prompt relationship of the nanoscale water layer with the water-mediated transfer of the TMDC. The super-wetting layer was found essential and critical for the effective transfer of TMDCs to other surfaces.