Solar steam-driven membrane filtration for high flux water purification

In recent years, interfacial solar steam generation has shown great potential for desalination with high solar-to-steam conversion efficiency. However, the freshwater production rate is still limited by the substantial latent heat of water evaporation and condensation efficiency. Here we designed an interfacial solar steam-driven reverse osmosis/nanofiltration device that generates high pressure that pushes water molecules through a filtration membrane to achieve separation from ions. The solar steam-driven reverse osmosis device reaches a water production rate as high as 81 kg m−2 h−1 under 12 sun illumination. Moreover, a theoretical model indicates that there still exists attractive room to further improve the freshwater output by optimizing the thermal insulation and expansion ratio of the device. This work paves a new way to design highly efficient miniaturized or decentralized drinking water devices. Reverse osmosis of seawater is a popular though energy demanding process to produce freshwater. Interfacing reverse osmosis membranes with solar steam generation shows potential for a more efficient desalination process.