Fig. 2.

Two-dimensional (2D)-AFM xz force maps and force–distance curves of 2D materials–water interfaces. a Graphene. b Few-layer MoS₂. c Few-layer WSe₂. Scale bars represent 0.5 nm (both horizontally and vertically). d Force–distance curve for the graphene–water interface (extracted from a). e Force–distance curve for the MoS₂-water (extracted from b). f Force–distance curve for the WSe₂–water interface (extracted from c). The data show some oscillations in the force. Each peak is associated with a single molecular layer