Issue 21, 2024

On the origin of the surface superhydrophobicity of rough-textured inorganic materials with intrinsic hydrophilicity

Abstract

In mechanism, surface superhydrophobicity is often thought to be the result of the trapped air within the grooves of a superhydrophobic surface, leading to a composite solid–liquid–air interface. However, the mechanism cannot reasonably reflect why the rough surfaces of intrinsically hydrophilic materials are capable of showing hydrophilicity or superhydrophobicity. In this work, several typical rough-textured inorganic materials (i.e. metal oxide, sulfide, selenide and halide) endowed with intrinsic hydrophilicity are taken as examples to reveal the superhydrophobic origin of intrinsically hydrophilic materials. The wettability of these rough-textured surfaces is usually hydrophilic when dried in N2, while it is hydrophobic or superhydrophobic when dried in O2. This distinct difference in wettability is closely related to anion vacancies of anions such as oxide, sulfide and halide ions. From the generation of H2O2 in water droplets on the rough-textured surfaces, it is found that the H2O2 yield increases with an increase in their hydrophobicity and decreases with an increase in their hydrophilicity, indicating an evident dependence of their surperhydrophobicity on the absorption of O22− on their surfaces. DFT calculation shows that introducing Va can give a higher adsorption-energy for molecular oxygen species (especially O22−) than N2 and H2O. Hence, we propose that the presence of abundant Va on intrinsically hydrophilic inorganic materials can result in the formation of preferential O22− adsorption layer in their grooves, which endows these inorganic materials with superhydrophobicity. Our results can provide further insight into the origin of superhydrophobicity in intrinsically hydrophilic materials and guide the design of water-proof functional surfaces.

Graphical abstract: On the origin of the surface superhydrophobicity of rough-textured inorganic materials with intrinsic hydrophilicity

Supplementary files

Article information

Article type
Research Article
Submitted
13 aug 2024
Accepted
04 sep 2024
First published
06 sep 2024

Inorg. Chem. Front., 2024,11, 7382-7389

On the origin of the surface superhydrophobicity of rough-textured inorganic materials with intrinsic hydrophilicity

R. Wen, X. Chen, G. Qi, W. Li and Z. Yuan, Inorg. Chem. Front., 2024, 11, 7382 DOI: 10.1039/D4QI02059F

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