Activating water via precisely patterned wettability domains for low-enthalpy evaporation with a lotus-seed-pod inspired hydrogel

Solar-driven brine desalination faces two critical challenges: the high energy barrier of water vaporization and severe salt accumulation. To address these, we designed a lotus-seed-pod inspired hydrogel evaporator with a hierarchical structure and heterogeneous interface. By precisely patterning hydrophobic domains on a hydrophilic network on heterogeneous interface, the interface actively reconfigures hydrogen-bonding, enriching weakly bonded intermediate water and reducing the vaporization enthalpy by 26.6%. This thermodynamic advantage, coupled with synergistic thermal and solutal Marangoni convection, yields robust, self-regulating salt resistance. Consequently, the evaporator achieves a high evaporation rate of 2.82 kg·m −2 ·h −1 at 92.2% efficiency in 20 wt% brine, maintaining zero salt crystallization over 240 h of continuous operation. Numerical simulations further confirm that precise regulation of the spatial distribution, strength, and connectivity of hydrogen bonds simultaneously optimizes water transportation. This work reveals that bio-inspired interfacial design with patterned wettability and confinement domains lowers the phase-change energy barrier, enabling efficient, salt-resistant solar evaporation for sustainable water technologies.