Hierarchical micro- and nanostructures induced by nanosecond laser on copper for superhydrophobicity, ultralow water adhesion and frost resistance

The low-cost fabrication of large-area hierarchical micro-and nanostructures is critical for the practical applications of superhydrophobic metallic surfaces. Instead of using ultrafast lasers, low-cost near-infrared nanosecond (ns) lasers were used in this study to induce the formation of hierarchical micro-and nanostructures on copper surfaces. We found that the ns laser-treated surfaces with medium-height microstructures densely covered by nanoparticles demonstrated stable superhydrophobicity, lower water adhesion and superior frost resistance. In the experiment, the micro-and nanostructures induced by treatment with ns lasers with a pulse width of 100 ns showed better performance in term of superhydrophobicity, water adhesion and frost resistance. However, the obtained structures were sensitive to the laser pulse energy when long pulse widths were used. The advantage of short laser pulses was that, hierarchical micro-and nanostructures with good performance could still be obtained with low laser energy. Our findings prove that low-cost ns lasers are also suitable for the fabrication of metallic superhydrophobic surfaces and that different applicable laser parameters are needed when the laser pulse width varies. (C) 2018 Elsevier Ltd. All rights reserved.