Easy access to robust rigid SiO2-based photothermal aerogel for enhanced solar interfacial evaporation

Solar-driven interfacial evaporation has received increasing attention as a method for desalination of seawater and purification of wastewater due to its advantages such as low energy consumption and sustainability, but the development of evaporators with high water transportability, mechanical properties and light-to-vapor efficiencies has been difficult to achieve simultaneously. Herein, an environmentally friendly, simple-to-prepare and robust rigid solar evaporator with excellent hydrophilicity and thermal insulation is demonstrated. Polypyrrole (PPy) is in-situ grown on SiO2 aerogel so that impart the SiO2/PPy composite with efficient thermal insulation and light absorption. Sodium alginate (SA) is used as a binder to form rigid photothermal converting aerogel with high compressive stress (4.13 MPa) and 3D porous structures in which perform high-performance solar interfacial evaporation with reduced evaporation enthalpy. As a result, the SiO2/PPy/SA evaporator exhibits water evaporation rate of 2.17 kg m-2h−1 and a high light-to-vapor efficiency of 94.17 % under the light intensity of 1 kW m−2. In addition, the solar evaporator also has long-term operational stability and salt rejection, which is expected to be potentially applied in freshwater production via seawater desalination.