Facile synthesis of hierarchical SnSe nanosheets-hydrogel evaporators for sustainable solar-powered desalination

In contrast to the demand for freshwater that is increasing continuously due to population growth and economic growth, the availability of freshwater resources is decreasing rapidly due to environmental pollution and climate change. Solar-powered desalination is an eco-friendly and efficient way to produce freshwater. Herein, a facile method based on the Rayleigh-Benard convection was developed to synthesize hierarchical nanomaterials-hydrogel evaporators. The SnSe nanosheets were encapsulated in poly(hydroxyethyl 2-methacrylate) hydrogel, and the resultant thin, porous SnSe-hydrogel composite layer was seamlessly integrated into the hydrogel matrix. Under one-sun irradiation, the SnSe-hydrogel evaporator demonstrated a high water-evaporation rate (2.20 kg m(-2) h(-1)) and high energy conversion efficiency (91.70%). Moreover, the evaporator not only had excellent long-term mechanical properties, but also demonstrated excellent ion-rejection rates during a long-term seawater evaporation test, which indicated the potential application of the evaporator to sustainable solar-powered desalination in the offing or on ocean-going vessels. Our results provide a route for the synthesis of functional nanocomposite hydrogels for solar-powered water purification, sensing, biomedical, and other fields.