Surface Patterning of Two-Dimensional Nanostructure-Embedded Photothermal Hydrogels for High-Yield Solar Steam Generation

Improving evaporation rate is extremely important to promote the application of solar steam generation in clean water production through seawater desalination. However, the theoretical evaporation rate limit of a normal two-dimensional (2D) photothermal evaporator is only about 1.46 kg m^-2 h^-1. While 3D evaporators can break the limit, they require much more raw materials. In this work, an effective approach for achieving high-yield solar steam generation via the synergy of 2D nanostructure-embedded all-in-one hybrid hydrogel evaporator and surface patterning is reported. This improved surface-patterned evaporator is able to simultaneously lower the enthalpy of vaporization and induce the Marangoni effect near the evaporation surface, thus delivering a high evaporation rate of 3.62 kg m^-2 h^-1, which is more than twice the theoretical limit of the normal 2D photothermal evaporator. This hybrid hydrogel offers a cost-effective and energy-efficient pathway to mitigate clean water shortages.