Tailoring Nanoscale Surface Topography of Hydrogel for Efficient Solar Vapor Generation.

Solar vapor generation, which can separate the soluble or dispersing contaminants from water, is particularly desirable owing to its green energy utilization for water purification technology. Here, we present a concept of enhancing solar vapor generation by tailoring surface topography of the hydrogel-based solar evaporator. Via nanotexture-enhanced heat flux at the evaporation front, the obtained solar evaporator achieves a water evaporation rate of ∼2.6 kg m h at ∼91% energy efficiency under one sun (1 kW m). An easy-to-install solar still based on this solar evaporator consisting of cost-effective poly(vinyl alcohol) and activated carbon is deployed to demonstrate the potential for domestic or urgent water purification purposes. Such new design principles of hydrogel-based solar evaporators provides a useful means for surface-enhanced water evaporation to inspire scalable and processable solar evaporators from accessible raw materials.