Integrating High-Entropy Alloy with Hierarchical Hydrogels for Enhanced Solar-Driven Water Desalination

Developing high-performance photothermal materials represents a critical pathway toward achieving efficient solar-driven water desalination. Herein, we synthesize FeCoNiCuZnMn high-entropy alloy nanoparticles anchored on a carbon nanotube substrate and subsequently incorporate them with polypyrrole and poly(vinyl alcohol) into a hierarchical hydrogel network (FeCoNiCuZnMn HEA-NPs/CNT/PPy@PVA) for highly efficient and stable solar-driven water evaporation. Experimental evidence confirms that the interfacial evaporation performance arises from three synergistic mechanisms: (i) near-unity solar absorption (95.24%) enabled by FeCoNiCuZnMn HEA-NP/hydrogel heterojunctions, (ii) reduced evaporation enthalpy (1731.03 kJ/kg) through PVA-mediated hydrogen bond restructuring, and (iii) enhanced mechanical-environmental stability via integration of HEA-NPs' robustness with hydrogels' eco-compatibility. Consequently, the as-prepared system achieves performance for interfacial evaporation, demonstrating 96.9% photothermal conversion efficiency and an evaporation rate of 2.22 kg m^-2 h^-1 under 1 sun irradiation, while maintaining operational stability. Practical field tests confirm successful desalination of seawater (3.5 wt %) to World Health Organization-compliant drinking water. This work establishes design principles for photothermal materials through multiscale regulation of energy-water interactions.