Bioinspired photothermal conversion coatings with self-healing superhydrophobicity for efficient solar steam generation

Photothermal conversion materials are prone to contamination caused by microorganisms and mud in water and to damages caused by oxidative substances, corrosive liquids and ultraviolet light, thereby greatly limiting the practical application of solar steam generation. Inspired by lotuses, in this study, scalable, chemically and mechanically stable, and conductive photothermal conversion coatings with self-healing superhydrophobicity are fabricated by spraying a mixture of beeswax, multiwalled carbon nanotubes and polydimethylsiloxane. The resulting photothermal conversion coatings exhibit broadband light absorption ability and can thus efficiently generate steam under sunlight irradiation. The integration of superhydrophobicity provides the photothermal conversion coatings with a self-cleaning ability that can prevent the reduction of steam generation efficiency induced by microorganisms and mud in water. In addition, the photothermal conversion coatings are capable of healing damage to their superhydrophobicity through the migration of beeswax, providing long-lasting protection. Furthermore, the photothermal conversion coatings possess an electric steam generation ability, which allows the coatings to continuously generate steam when sunlight is not available. Considering their low maintenance requirement, simple preparation process and high cost effectiveness, photothermal conversion coatings with self-healing superhydrophobicity may be suitable to provide fresh water for remote/disaster areas.