Overcoming Raoult's Law via Ligand Field Polarization‐Mediated Interfacial Water Activation for High‐Performance Solar Evaporation

ABSTRACT

In traditional saline water evaporation systems, water evaporation is severely suppressed by salt solute, which strictly follows Raoult's law and thus hinders the solar‐driven evaporation. Herein, a ligand field‐induced electrostatic polarization strategy is proposed to thermodynamically activate water molecules through disrupting the ideal solution behavior restricted by Raoult's law. By co‐coordinating Fe ³⁺ and Co ²⁺ within a sodium alginate hydrogel network, pronounced electron redistribution is induced in the polymer framework, generating a polarized coordination environment that disrupts the cooperative hydrogen‐bond network of water and thereby decreases the water vaporization enthalpy significantly. Combined with a biomimetic hierarchical hydrogel featuring a bubble‐channel and dual‐network architecture, the embedded microcavities substantially expand the active evaporation interface, while the bimetal‐regulated axial pumping and radial wetting dual‐network enables efficient water transport and localized heat management. Therefore, the optimized hydrogel achieves a high apparent evaporation rate of 5.82 kg m ⁻² h ⁻¹ under 1‐sun irradiation. Moreover, the atomically dispersed transition metal sites provide intrinsic catalytic activity for efficient degradation of organic pollutants. This work demonstrates an integrated strategy combining ligand field‐driven thermodynamic water activation with multiscale dual‐network engineering, offering a versatile platform for solar‐driven desalination and wastewater purification in both remote and off‐grid areas.