Confined Shape-Morphing and Dual Hydration Modes for Efficient Solar Steam Generation

Hydrogels are ideal substrates for interfacial solar steam evaporation because of their tunable water evaporation enthalpy. However, conventional hydrogel-based evaporators suffer from severe shape-morphing and slow water transportation dominated by osmotic hydration. Inspired by the space-confined effect in plant cell walls, we propose to construct a 3D skeleton-supported hydrogel evaporator, which can develop against its shape deformation by meshing the bulk hydrogel into many confined microspaces, resulting in an interconnected porous structure. Benefiting from the unique porous architecture, the dual capillary–osmosis water supply modes are achieved to overcome the slow osmotic hydration in conventional hydrogels. With componential and structural optimization, the hydrogel evaporator presents an evaporation rate of 3.0 kg·m–2·h–1 under 1-sun irradiation with an energy efficiency of 90%, which can even be maintained under 8-sun illumination due to the sufficient water supply. This structural design paves the way for feasible hydrogel evaporators' applications in water purification.