Bioinspired surface combines sunlight and electric heating for all-weather anti-icing and de-icing

Ice accumulation on aircraft, power lines, rail systems and other outdoor infrastructure can create serious safety risks and increase maintenance and energy costs. Conventional de-icing methods often require considerable energy or chemical treatments. Solar-driven photothermal surfaces provide a more energy-efficient alternative, but their performance can decline when sunlight is weak or unavailable. To address this challenge, a research team has developed a photothermal-electrothermal superhydrophobic surface, called PTESS, that combines passive anti-icing with solar-driven photothermal heating and electrically controlled heating. This combination allows the surface to adapt to changing light conditions and provides a potential approach to all-weather anti-icing and de-icing.

Inspired by the water-repellent structure of lotus leaves, the researchers created a hierarchical surface on an Fe-based amorphous alloy substrate. Selective laser melting was first used to fabricate hemispherical microscale structures, followed by the deposition of a nanostructured tungsten oxide layer using magnetron sputtering. The resulting micro and nanoscale structure greatly reduces the contact between water and the solid surface while trapping air beneath water droplets. This gives the surface strong water repellency, with a water contact angle above 150 degrees and a sliding angle below 5 degrees. The trapped air layer also acts as a thermal barrier, slowing heat transfer between water and the cold substrate and helping to delay freezing.

The tungsten oxide layer provides strong light absorption and converts solar energy into heat. The surface absorbs more than 90 percent of light across a broad wavelength range. Under one-sun illumination, its temperature reached about 50 degrees Celsius. In de-icing experiments, an ice-covered surface initially cooled to minus 15 degrees Celsius completed ice melting within about 180 seconds under one-sun illumination. Sunlight, however, is not always available. Under weak-light or dark conditions, the conductive Fe-based amorphous alloy substrate can be electrically heated using an external power supply. This electrothermal function compensates for the loss of solar heating and enables active de-icing when photothermal heating alone is insufficient. The researchers also tested photothermal and electrothermal heating together. Under the reported experimental conditions, combining the two heating modes accelerated ice melting and achieved complete de-icing in approximately 60 seconds, demonstrating the benefit of integrating the two heat sources in a single surface. The hierarchical structure also helps prevent ice formation before active heating is needed. In freezing experiments, a water droplet on PTESS remained liquid for about 120 seconds, while a droplet on a flat reference surface froze into a uniform ice layer within about 60 seconds. The PTESS also maintained lower ice adhesion than the flat surface after repeated icing and de-icing cycles.

In addition to anti-icing and de-icing, the surface demonstrated other functions that may be useful in demanding environments. It provided electromagnetic shielding effectiveness of approximately 38 to 40 db in the X-band, corresponding to more than 99.9 percent electromagnetic attenuation, and also showed flame-retardant properties. The researchers further observed a photoelectric response and limited charge-storage capability. However, the stored electrical energy is currently insufficient to independently power de-icing at night. In the reported experiments, electrothermal de-icing under dark conditions was powered by an external voltage source. The photoelectric behavior instead points to the possibility of future energy-assisted or self-powered anti-icing systems. By bringing together passive ice resistance, solar-driven heating and controllable electrical heating, the PTESS provides a new strategy for developing adaptive anti-icing and de-icing surfaces. Its combination of anti-icing, de-icing, flame-retardant and electromagnetic-shielding functions may offer potential for transportation, energy infrastructure and other systems operating in cold or harsh environments.

The research was conducted by researchers from Jilin University and Dalian University of Technology, with participation from the School of Mechanical and Aerospace Engineering at Jilin University, the Key Laboratory of Advanced Materials Additive Manufacturing of Jilin Province, the National Key Laboratory of Automotive Chassis Integration and Bionics, the Key Laboratory of CNC Equipment Reliability of the Ministry of Education, and the State Key Laboratory of High-performance Precision Manufacturing.