Fabrication of Co(3)O(4) hierarchically superhydrophobic boat-like hollow cages at the silicon surface
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Updated: May 30, 2026

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars
Published on: February 11, 2020
Zhiguang Guo1, Weimin Liu, Bao-Lian Su
1State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Middle Road 18#, Lanzhou 730000, People's Republic of China. Laboratory of Inorganic Materials Chemistry (CMI), University of Namur, 61 Rue de Bruxelles, Namur B-5000, Belgium. School of Materials Science and Engineering, Hubei University, Wuhan 430062, People's Republic of China.
Abstract:
By employing a simple bottom-up method for the first time and using ideas learned from nature, especially from the lotus leaf, we fabricated unique Co(3)O(4) hierarchical boat-like hollow cages about 30 µm in length and 8 µm in width at the middle constituted of many nanorods and nanoparticles. The various morphologies of the products can be tailored from nanoparticles to nanorods and to microcages by tuning the concentration of Co(NO(3))(2)·6H(2)O. We believe that ammonia employed in this method plays not only the role of ligand to ensure the oxidation of Co(2+) to Co(3+) but also helps with the variation of concentration for the final morphologies. The products, which might be used as catalysts and microreactors, show superhydrophobic properties after chemical modification with poly(dimethylsiloxane) vinyl-terminated (PDMSVT) compound. It is confirmed that the synergic effect of the surface morphology and the surface free energy contribute to this unique surface water repellence.

