Figure 1. The nano-sponge (hydrocarbon/TiO₂ NPs) and its oil absorption and desorption capacity underwater.

(a) Fabricated nano-sponge/porous PDMS (NS/p-PDMS) by dip coating. (b) SEM image of the surface structure of the 6/4 NS/p-PDMS. The bright contrast and dark contrast materials are TiO₂ and hydrocarbon, respectively. The inset shows a low magnification image of the NS/p-PDMS, indicating its porous structure. (c) Compositional distribution by TEM-EELS mapping; C (red), O (blue), Ti (green). The inset shows a bright field image of the 6/4 nano-sponge. (Scale bar = 50 nm) (d) Underwater crude oil absorption of the 6/4 NS/p-PDMS, (e) fully absorbed state, and (f) oil desorption with air bubble flow/UV irradiation. (g) A schematic procedure of oil absorption and desorption with UV-responsive wettability and air bubble flow.