Scalable fluorine-free superhydrophobic photothermal coating based on boron carbide and candle soot for anti-icing and photothermal de-icing

Abstract

Ice accumulation on outdoor infrastructure such as transmission lines, wind turbine blades, and aircraft wings under freezing conditions poses severe safety risks and operational inefficiencies. Passive anti-icing strategies based on superhydrophobic surfaces have shown promise, yet their effectiveness diminishes under extreme cold, high humidity, or dynamic icing scenarios. Integrating photothermal functionality with superhydrophobicity offers a viable route toward anti-icing/deicing applications. In this study, a fluorine-free, mechanically robust superhydrophobic photothermal coating was developed by combining boron carbide (B₄C) micro-particles and candle soot nanoparticles within polydimethylsiloxane (PDMS) via a scalable spray-coating process (Candle@BC coating). OTMS was grafted onto B₄C through Si–O–B covalent bonds, while PDMS interacted with the modified particles via physical entanglement rather than direct covalent condensation. The coating exhibits a micro–nano hierarchical structure, achieving a water contact angle of 160° and a sliding angle of 2.5°. It demonstrates a broadband solar absorption of 96.7% and reaches a photothermal equilibrium temperature of 96.3 °C under 1 sun irradiation. The photothermal conversion mechanism is systematically verified by real-time infrared thermal imaging, quantitative efficiency tests, and COMSOL simulations, confirming the synergistic effect between B₄C interband absorption and candle soot broadband light harvesting. The coating significantly delays ice formation, with freezing times prolonged by up to 5.77 times compared to bare substrates in the temperature range of −10 °C to −40 °C. Moreover, under 1 sun illumination, the coating enables rapid photothermal deicing, with ice droplets sliding off within 98 s at −10 °C and ice layers completely detached within 375 s. The coating also exhibits excellent mechanical durability, chemical stability, and environmental adaptability, verified by abrasion, tape peeling, sand impact, acid–alkali immersion, and extreme-environment exposure tests. This work provides a feasible and scalable approach for fabricating high-performance photothermal superhydrophobic coatings for all-weather anti-icing and de-icing applications in harsh environments.