Air-template assisted enhancement of solar steam generation

Hydrogel-based solar interfacial evaporation technology, taking advantage of its low evaporation enthalpy and efficient water transport capability, presents a novel approach to addressing global water scarcity. However, conventional hydrogel systems are restricted by insufficient regulation of dynamic swelling equilibrium. In low-swelling states, hydraulic permeability is limited, while excessive swelling causes pore structure collapse and subsequent blockage of mass-transfer channels, severely impeding the continuous improvement of evaporator performance. Herein, an air-template-guided construction strategy was established to construct hydrogels with architecturally ordered macroporous channels. Compared with non-templated hydrogels, it achieves a 45.45 % increase in water vapor transmission rate and a remarkable 131.25 % enhancement in evaporation rate. Additionally, the incorporation of expanded graphite constructs a heterogeneous interface that effectively suppresses hydrogel swelling while synergistically optimizing photothermal conversion efficiency. Under solar radiation intensities of 50–77 mW/cm², the evaporator demonstrates a stable water collection rate ranging from 26.5 to 32.7 L/m²/day. This research provides a simple and effective solution to the challenge of rapid water transport in hydrogel systems.