Anisotropic 3D Aerogel of Graphene Oxide and Poly(Vinyl Alcohol) for Desalination by Interfacial Solar Vapor Generation

Interfacial solar vapor generation (ISVG) is a promising water treatment technology because it minimizes the carbon footprint and addresses water shortages. To further improve the solar energy efficiency in carbon material-based ISVG process, graphene oxide (GO) nanosheets and poly(vinyl alcohol) (PVA) are adopted as precursors for fabricating a three-dimensional aerogel (radial-GO/PVA) with anisotropic porous structure using an oriented freeze-casting technique. Experiments and numerical simulations reveal that benefiting from the horizontally radial struts and longitudinally lamellar struts with transversely parallel ligaments, radial-GO/PVA aerogel performs multifunctional features for ISVG, including excellent light absorption, rational water adjustment, good thermal management capability, and efficient salt rejection. A water evaporation rate of 1.58 kg·m–2·h–1 can be achieved under the standard solar irradiation (1 kW·m–2). More importantly, radial-GO/PVA aerogel exhibits a long-term stability for continuous water evaporation over 8 h in a concentrated 20 wt % NaCl solution, indicating the potential application for the desalination and purification of high concentration brine through ISVG route.