Freshwater-electricity co-generation in solar-driven water desalination: an effective approach toward the water-energy nexus

It is urgent to exploit the ability of water-energy co-generation technologies to address the challenges and opportunities for the water-energy nexus. This report presents a cuboid-shaped interfacial solar steam generator made of a selective solar absorber-coated aluminum sheet with filter paper strips attached to its four outer walls as the evaporating surfaces and water-conducting paths for simultaneous freshwater and electricity generation from saltwater (3.5 wt% of NaCl). Connecting all four strips in series, a device with an illumination area of only 1.5 x 1.5 cm(2) can generate an open-circuit voltage of 2.7 V with sufficient power to continuously glow an LED during evaporation, without any energy storage devices, in addition to an evaporation efficiency of 88%. For the first time, we could generate sufficient electricity from a single evaporator in a continuous manner to realize practical applications without scaling up, even in the dark. Our device promotes interface solar steam generation as a promising alternative to the solar-driven water-energy nexus.