Hierarchical porous aero-cryogels for wind energy enhanced solar vapor generation

An integrated aero-cryogel (A-CG) monolith with hierarchical porous structure was developed by inter-crosslinking of cellulose nanofiber/polylactic acid nanocomposite aerogel and carboxymethyl cellulose (CMC) cryogel (CG). The photothermal nanoparticles-enriched CMC CG phase served as a sunlight absorbing layer, exhibiting a broadband sunlight absorption of 98%. Due to the large amount of weakly bounded water molecules, the swelled CMC CG possessed a lower evaporation enthalpy than that of pure water, which facilitates water evaporation, while the nanocomposite aerogel phase acted as an excellent thermal insulator and afforded highly efficient water transport channels. Thus, the developed A-CG monolith supported by insulated polystyrene foam to protrude above the water surface, could reach an evaporation rate of 2.16 kg m⁻² h⁻¹ under an irradiation of 1 Sun (100 mw/cm²) with an efficiency of 93.6%. More remarkably, when the wind energy was imparted, an evaporation rate of 5.67 kg m⁻² h⁻¹ was achieved at a wind speed of 3 m s⁻¹. The high-efficiency purification outcomes of various raw water demonstrate the great potentials of A-CG material in solar vapor generation.