Efstratios Mitridis1 Alba Sicher2 Claudio Hail1 Eghlidi Hadi1 Thomas Schutzius1 Dimos Poulikakos1

1, ETH Zürich, Zurich, , Switzerland
2, ETH Zürich, Zürich, , Switzerland

Understanding and controlling ice nucleation and accretion on surfaces is an important area of research due to its prevalence in nature and technology. Ice formation can negatively affect numerous activities and applications, including aviation, power transmission, road transportation, solar energy harvesting, and shipping. To prevent ice accretion, active anti-icing protection systems are employed, such as chemical treatment or heating, and their expenditures are expected to be >$10 billion by 2021 [1]. Both approaches have economic drawbacks as well as environmental (chemicals) and energy concerns, the latter (heating) generally consuming non-renewable sources. Here we show that by leveraging sunlight (renewable energy source, ~1 kW m-2), one can use rationally engineered solar metamaterial absorbers to induce localized heating and perform anti-icing (significant nucleation delay of water droplets) and de-icing (partially melting and removing adhering ice). An important point of this approach is that the surfaces can be partially transparent while also absorbing a significant fraction of the incident solar irradiation. A ~10 oC temperature increase, rapid deicing and 10s’ orders of magnitude boosted inhibition of water condensate and frost formation have been experimentally achieved for semi-transparent films, towards surfaces with significant performance against icing even under nominal sun power (~1 kW m-2). Guided by thermoplasmonics and percolation theory, the films are fabricated as gold–dielectric nanocomposites with a broadband absorption in the visible light regime, owing to localized surface plasmon oscillations in the nanometer-scale, which then dissipate into heat. The films retain the same level of performance for several freezing cycles. In comparison with electrically-heated de-icing surfaces, energy efficiency, transparency and immunity to photodegradation are three important aspects where these nanomaterials are superior. Our research into solar metamaterial absorbers represents a feasible, environmentally friendly approach to anti-icing and de-icing. We expect its relevance to extend beyond environmentally-friendly applications, wherever transparency or ultra-low thickness are a must, for instance in windshields and optical elements.

[1] MarketWatch. 2017. Ice Protection Systems Market Worth 10.17 Billion USD by 2021. 10 March. Accessed October 30, 2017.