fig4

Figure 4. Wetting transparency of atomically thin 2D materials in Figure 4A-C. (A) WCA on Cu and Cu-supported graphene of different numbers of layers^[31]; (B) Schematic of the interaction range of water molecules on the bare substrate and substrate-supported graphene; (C) Summary of experimentally measured WCAs on the bare substrate θ_Substrate and on substrate-supported monolayer 2D materials θ_App^{[9,11,14,16,28,31,77,78,81,82,116,120]}. The horizontal dashed lines represent the contact angles of aged graphite (around 97°) and clean, suspended monolayer graphene (around 30°), respectively, while the oblique dashed lines represent the condition for wetting transparency of 2D materials, i.e., θ_Substrate = θ_App. Figures A is adapted from reference^[31] with permission. WCA: Water contact angle; 2D: two-dimensional.