Synergistic water activation on high-entropy alloy oxides enables ultralow-enthalpy solar desalination

• The CCH evaporator achieves 2.627 kg m -2 h -1 evaporation rate and 94.2% efficiency under one sun • HEAO surface exhibits "hydrophilic-electronic" properties, activating water molecules and reducing evaporation enthalpy • The CCH shows high desalination efficiency and stability in various salinities and pH conditions Amidst the escalating global freshwater crisis, solar interfacial evaporation (SIE) stands out as a promising desalination technology, yet its inherent efficiency is fundamentally constrained by the high enthalpy of water vaporization. Herein, we introduce a paradigm-shifting strategy to overcome this limitation by leveraging the unique properties of high-entropy alloy oxides (HEAO). The facile in-situ uniform synthesis of (FeCoNiCuCr) 3 O 4 HEAO nanoparticles on carbon cloth (CC) substrates was achieved via flash Joule heating. Our core innovation lies in the discovery that the HEAO functional layer creates a "hydrophilic-electronic" dual-property surface, which, through the synergistic effect of multi-valence metal sites and oxygen vacancies, actively reconstructs the hydrogen bond network of interfacial water. This manipulation leads to a significant reduction in the apparent evaporation enthalpy to just 1290.9 J g -1 . Consequently, our composite evaporator (CCH) achieves an outstanding evaporation rate of 2.627 kg m -2 h -1 under one sun illumination. Furthermore, combining advanced XPS analysis with density functional theory (DFT) calculations, we provide the atomic and electronic-level evidence for this synergistic mechanism, illuminating the geometric and electronic activation of interfacial water molecules. This work provides an advanced material solution for efficient and stable solar desalination and a transformative theoretical perspective for designing next-generation phase-change materials. Table of Contents: A high-entropy alloy oxide evaporator, synthesized via flash Joule heating, lowers water's evaporation enthalpy by creating a "hydrophilic-electronic" surface with synergistic multi-valence and oxygen-vacancy sites. This mechanism enables an exceptional evaporation rate of 2.627 kg m -2 h -1 and 94.2% efficiency, offering a transformative solution for high-performance solar desalination.