Halloysite-Based Inorganic Aerogel Evaporator for Efficient Solar Interfacial Seawater Evaporation

Solar interfacial seawater evaporation is an efficient and convenient way to tackle the freshwater crisis. Despite the fact that many organic-based aerogel evaporators have achieved high solar-vapor efficiency and high evaporation rates, they are usually difficult to adapt to freshwater extraction in complex environments due to the low strength and inability to resist corrosion of organic components. Fabricating high-strength and corrosion-resistant aerogel evaporators from low-cost inorganic materials is more meaningful but still challenging. To this end, a high-strength, pure, and bilayered inorganic aerogel evaporator (CuS@HNT/HBK) was rationally designed and created, in which CuS nanoparticles were grown on the HNT surface (CuS@HNT) as the upper photothermal absorber, while boric acid and γ-glycidyl etheroxypropyltrimethoxysilane (KH560) were used as high-temperature adhesives to bind HNT (raw-HBK) as a high-strength substrate after sintering (HBK). CuS@HNT/HBK demonstrates remarkable seawater evaporation performance with high evaporation rates of 1.52/4.73 kg m–2 h–1 under one/three solar irradiation, outperforming most of the organic–inorganic and pure inorganic aerogel evaporators previously reported. Molecular simulations reveal that the removal of hydroxyl groups on the HBK surface reduces the binding of water molecules, thereby significantly promoting the evaporation of the CuS@HNT/HBK. Impressively, CuS@HNT/HBK possesses extraordinarily high compressive strength of 4.8 MPa and compressive modulus of 31.7 MPa, and it is very stable in acidic/alkaline solutions and dyes wastewater, guaranteeing its long-term stability, flexibility, and adaptability in various extreme conditions. This work puts forward a feasible idea to develop efficient, high-strength, and corrosion-resistant pure inorganic aerogel evaporators for potential application in complex water environments.