Integrated photothermal aerogels with ultrahigh-performance solar steam generation

Highly efficient solar steam generation (SSG) relies on excellent light absorption, adequate water transportation, a large evaporation area, and high thermal management capability in coherent photothermal materials. However, there is not yet a general means of integrating these functions on a monolith with design flexibility in chemical compositions and pore structure. Here, we design and demonstrate a versatile chitosan (CS) aerogel that is easily compatible with other photothermal materials for high-efficiency SSG. The CS aerogel was synthesized through liquid-phase one-pot freeze drying without any cross-linkers. CS composite aerogels not only preserved the initial characteristics of the CS aerogel but also integrated biocompatible, hydrophilic and high thermal insulation properties, as well as enhanced light absorption ability based on the designed porous structure through the effects of light trapping and multiple scattering. Carbonized pomelo peel particles composited with the CS aerogel and freeze dried by lyophilizer (PP_0.1CS_1.5-L) exhibited excellent SSG performance with an evaporation rate of up to 1.78 kg m⁻² h⁻¹, which is far beyond that attainable by two-dimensional SSG systems under normal solar irradiation of 1 kW m⁻². This research opens up a new avenue for the facile fabrication of reusable, low-cost, nontoxic, and high-performance functional aerogels.