Ion‐Regulated Water Activation in Plasmonic Aerogels for Highly Efficient and Salt‐Resistive Solar Desalination

Abstract Interfacial solar evaporation (ISE) offers a sustainable route for water purification, yet its practical application remains constrained by interfacial salt crystallization, inefficient water activation, and operational instability in hypersaline or contaminated environments. Herein, an ion‐regulated plasmonic aerogel that couples broadband photothermal conversion with hydration‐state modulation for high‐performance solar desalination is reported. The engineered titanium nitride‐polyimide aerogel (TiN/PIA), fabricated via organic ice‐assisted unidirectional freeze‐casting, features hierarchical porosity, directional water transport channels, and exceptional salt‐rejection capability. Remarkably, the optimized evaporator, 0.4‐TiN/PIA, achieves an ultrahigh evaporation rate of 4.22 kg m ⁻² h ⁻¹ in 7 wt% saline and maintains 2.96 kg m ⁻² h ⁻¹ in 25 wt% hypersaline under 1‐sun illumination, exceeding performance in pure water. Mechanistic investigations reveal that Cl ⁻ ions reduce the evaporation enthalpy through Hofmeister salting‐in effects, validated by Raman spectroscopy, differential scanning calorimetry, and molecular dynamics simulations. Long‐term field trials demonstrate continuous operation with real seawater and industrial wastewater over 8 days without fouling. This study establishes a new paradigm of ion‐mediated water activation in photothermal materials and offers a robust platform for efficient solar‐driven water purification in real‐world conditions.