Wood-inspired aerogels with directional ordered pathways for rapid atmospheric water harvesting

Sorption-based atmospheric water harvesters (SAWH) provide a promising solution to the world's freshwater shortage problems. Inspired by the transpiration of wood, photothermal aerogels with directional ordered pathways were prepared using directional freezing technology. More importantly, the ultra-hygroscopic lithium composite (LC) converted from lithium chloride (LiCl) was loaded on these aerogels to perfectly solve the deliquescence and agglomeration problems after desorption, resulting in developing pectin/carbon nanotubes/ultra hygroscopic lithium composite (P/CNTs/LC) aerogels. Due to the ordered pathway structure of the pectin-based skeleton and the excellent hygroscopicity of LC, the aerogel exhibited significant water adsorption performance over a wide relative humidity (RH) range. COMSOL Multiphysics simulations and ANSYS predictions further revealed the intrinsic mechanism of the water adsorption kinetics, confirmed that water vapor transport in the ordered pathway structure was much faster than that in the disordered pathway structure. The adsorbed water can be quickly and completely desorbed under solar radiation, and remained stable after 60 adsorption/desorption cycles. The aerogel achieved continuous dehumidification and freshwater production (1.29 L·kg^-1·day^-1), demonstrating its potential for practical application. Our design offered a promising strategy for preparing high-performance SAWH for dehumidification and water harvesting applications.