Photothermal trap with multi-scale micro-nano hierarchical structure enhances light absorption and promote photothermal anti-icing/deicing

Facing climate change caused by carbon emissions and the disaster of ice accumulation on outdoor equipment, the large-scale use of solar energy is a promising solution. Here, a photothermal anti-icing material composed of substrate, carbon-based light-absorption layer, and encapsulation layer was prepared using a combined template-spraying method. The multi-scale micro-nano hierarchical structure can enhance light absorption in a limited space due to the light trapping effect, which was confirmed by ray-tracing simulation and the UV–vis-NIR light absorption result, and the average light absorption rate is up to ∼ 98% at the 200–2000 nm wavelength. The average surface temperature can reach ∼ 85 °C under 1 sun (qi = 100 mW/cm2) illumination at room temperature (Tr = 25 °C), and the photo-to-thermal conversion efficiency is up to 60.76%. Excellent photothermal conversion performance endows the material with the ability of photothermal deicing, and the frost or ice layer can melt and fall off from the surface after 300 s of 1 sun illumination. Besides, the photothermal anti-icing experiments under 1 sun illumination show that the prepared material has a lower freezing temperature (-25.20 ± 1.34 °C), a longer freezing delay time (774.76 ± 114.19 s), and a heat transfer model during the icing process was proposed. Surface friction, water flow impact, and solution immersion tests show that the material has excellent mechanical durability and chemical stability. The materials prepared in this work show enormous application potential on outdoor equipment due to the simple preparation method, strong mechanical durability, and excellent photothermal anti-icing/deicing properties.