Preparation and characterization of slice-like Cu2(OH)3NO3 superhydrophobic structure on copper foil

Superhydrophobic structure was prepared on copper foil via a facile solution-immersion method. Thus slice-like Cu₂(OH)₃NO₃ crystal was prepared on the surface of the copper foil by sequential immersing in an aqueous solution of sodium hydroxide and cupric nitrate. And the superhydrophobic structure was obtained by modifying the slice-like Cu₂(OH)₃NO₃ crystal with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). The morphologies, chemical compositions and states, and hydrophobicity of the surface-modifying films on the copper foil substrates were analyzed by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. Moreover, the thermal stability of the slice-like structure was also evaluated using thermogravimetric analysis (TGA). It was found that roughening of the copper foil surface helped to increase the hydrophobicity to some extent, but no superhydrophobicity was obtained unless the slice-like Cu₂(OH)₃NO₃ crystal formed on the Cu substrate was modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Besides, the superhydrophobicity of the FAS-17-modified slice-like Cu₂(OH)₃NO₃ structure was closely related to the surface morphology. And this hydrophobic structure retained good superhydrophobic stability at elevated temperature and in long-term storage as well, which should be critical to the application of Cu-matrix materials in engineering.