Figure 4. Footprint sizes of interfacial NDs at different solid surfaces under water.

When an emulsion droplet adsorbs onto the relatively hydrophilic Cu₂O particle surface and relatively hydrophobic Au surface separately via direct adsorption of emulsion droplet, the formed interfacial NDs have the same volume (V₂ = V₃ = V₁). The ND has relatively larger contact angle at Cu₂O surface than that at Au surface. The diameter of the footprint of NDs at Cu₂O surface (d₁) is smaller than that at Au surface (d₂).