Spatial Confinement Engineered Gel Composite Evaporators for Efficient Solar Steam Generation

Recently, solar-driven interfacial evaporation (SDIE) has been developed quickly for low-cost and sustainable seawater desalination, but addressing the conflict between a high evaporation rate and salt rejection during SDIE is still challenging. Here, a spatial confinement strategy is proposed to prepare the gel composite solar evaporator (SCE) by loading one thin hydrogel layer onto the skeleton of a carbon aerogel. The SCE retains the hierarchically porous structure of carbon aerogels with an optimized water supply induced by dual-driven forces (capillary effects and osmotic pressure) and takes advantage of both aerogels and hydrogels, which can gain energy from air and reduce water enthalpy. The SCE has a high evaporation rate (up to 4.23 kg m-2 h-1 under one sun) and excellent salt rejection performance and can maintain structural integrity after long-term evaporation even at high salinities. The SDIE behavior, including heat distribution, water transport, and salt ion distribution, is investigated by combining theoretical simulations and experimental results. This work provides new inspiration and a theoretical basis for the development of high-performance interfacial evaporators. The spatially confined hydrogel-modified interfacial evaporator (SCE) is prepared in this study. Dual-driven forces for water transportation of SCE including capillary effect and osmotic pressure ensure sufficient water supply for continuous evaporation up to 4.23 kg m-2 h-1 under one sun and excellent salt rejection performance that it can work in 20 wt.% saltwater stably for the long term. image