Salt-resistant continuous solar evaporation composites based on nonwovens with synergistic photothermal effect of graphene oxide/copper sulphide

Abstract

Solar interfacial evaporation is an innovative and environmentally friendly technology for producing freshwater from seawater. However, current interfacial evaporators are costly to manufacture, have poor tolerance to environmental conditions, exhibit instability in evaporation efficiency in highly saline solutions, and fail to prevent salt crystallization. The production of user-friendly, durable and salt-resistant interfacial evaporators remains a significant challenge. By spraying graphene oxide on a nonwoven material using PVA as a binder and adding biphasic Cu_xS by an in situ growth method, we designed 2D/3D micro- and nanostructured graphene oxide nanosheets/copper sulfide nanowires (GO/Cu_xS) with synergistic photo-thermal effects in the full spectral range. The evaporation efficiency in pure water was 94.61% with an evaporation rate of 1.5622 kg m⁻² h⁻¹. In addition, we enhanced convection by employing a vertically aligned water-guide rod structure design, where the concentration difference drives salt dissolution thereby reducing the formation of salt crystals. The evaporation efficiency in 20% salt water was 80.41% with an evaporation rate of 1.3228 kg m⁻² h⁻¹ and long-term stability of brine evaporation was demonstrated under continuous sunlight. This solar steam generator expands the potential application areas of desalination and wastewater purification.