Facile preparation of superhydrophobic copper surface by HNO3 etching technique with the assistance of CTAB and ultrasonication

Superhydrophobic rough structure was prepared on copper wafer via HNO₃ etching technique with the assistance of Cetyltrimethyl Ammonium Bromide (CTAB) and ultrasonication. After modification of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDTES), the copper wafer showed stable superhydrophobicity. The morphologies, chemical compositions and hydrophobicity of the substrates were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Dense and spherical micropits appeared on copper wafer after it was etched by 5 M nitric acid with 1.2 mM CTAB under ultrasonication for 20 min. The SEM results indicated that the joint action of CTAB and ultrasonication caused the formation of dense and spherical micropits.