The laser pulses produced microgrooves, on top of which densely populated lumpy nanostructures were formed. These structures essentially alter the optical and wetting properties of the surfaces of the three metals, turning the normally shiny surfaces velvet black (very optically absorptive) and making them water repellent.
Most commercially used hydrophobic and high optical absorption materials rely on chemical coatings that can degrade and peel off over time, said Guo. Because the nano and microstructures created by the lasers are intrinsic to the metal, the properties they confer should not deteriorate, he added.
The hydrophobic properties of the laser patterned metals also compare favourably with a famous non stick coating. "If you want to get rid of water from a Teflon surface, you will have to tilt the surface to nearly 70° before the water can slide off," Guo said. "Our surface has a much stronger hydrophobicity and requires only a couple of degrees of tilt for water to slide off."
Meanwhile, enhanced light absorption should benefit technologies that require light collection, such as sensors and solar power devices. The superhydrophobic surfaces can also clean themselves, as water droplets carry away dust particles efficiently.
