All-in-one polymer sponge composite 3D evaporators for simultaneous high-flux solar-thermal desalination and electricity generation

Abstract

Solar-thermal evaporation of seawater holds the potential for coproduction of freshwater and electricity, but conventional assembled bilayer two-dimensional (2D) evaporators often suffer from low vapor generation rates and poor performance stability. Herein, we report polyvinyl alcohol sponges compounded with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and carbon nanotubes as all-in-one 3D dual-functional solar-thermal evaporators for simultaneous high-flux desalination and electricity generation. The sponge composites possess high solar absorptance, hierarchical porous structure, strong anti-salt fouling capability and negatively-charged ionic channels. In particular, the enlarged 3D evaporation surfaces and the low evaporation enthalpy achieved a high evaporation rate of 6.8 kg m−2 h−1 and a high evaporation efficiency of 94.9% under one-sun solar irradiation. The evaporation-induced high-flux directional flow of seawater through the ionic channels within the sponges generate a stable potential of 117.8 mV. By connecting several sponge evaporators in series, we show that the integrated system can stably generate potable freshwater out of seawater under continuous solar irradiation to meet individual drinking need, and simultaneously produce sufficient electricity to power small electronic devices. The stable superior performance, integrated structure design and facile manufacturing process would make the all-in-one 3D sponge evaporators promising for renewable off-grid coproduction of drinkable clean water and electricity.