Fig. 2: Inhomogeneous water film induced solar-driven water evaporation enhancement.

a–d Time sequence of optical captures displaying the ultra-fast water upward spreading process on the biomimetic 3D evaporator surface. Scale bars are 2 mm. e–h 3D reconstruction of the equilibrium state of the biomimetic 3D evaporator in the wet state through Micro-CT from different viewing points. Panels (e), (f), and (g) are the scheme of the Micro-CT configuration, side view Micro-CT, and cross-sectional Micro-CT images of the reconstructed wet sample, respectively. Ethylene glycol (EG) with high boiling poit is utilized as the test liquid to reduce the influence of the liquid evaporation during Micro-CT characterization process. The red dot line in (g) represents the contact line between liquid and the microcavity structure of the biomimetic 3D evaporator. h Micro-CT image of the solely reconstructed hierarchical water pathway with thickness gradient generated on the biomimetic 3D evaporator surface. i The mass change of the water on the biomimetic 3D evaporator under one sun illumination (1 kW m⁻²), with pure water and 2D plane as controls. Red, blue, and black lines represent mass-change curves of the biomimetic 3D structure, the 2D plane, and pure water under one sun illumination, respectively. j The mass change of the water on the biomimetic 3D evaporator in darkness, with pure water and 2D plane as controls. Red, blue, and black lines represent mass-change curves of the biomimetic 3D evaporator, the 2D plane, and pure water in darkness, respectively.