High-Performance Solar Desalination of Seawater Using a Hydrophilic WS ₂ /Poly(vinyl alcohol) Sponge Evaporator

Interfacial solar steam generation (ISSG) has emerged as an attractive technology for sustainable seawater desalination. However, overcoming salt accumulation, enhancing water transport, and ensuring long-term operational stability remain key challenges for its practical deployment. In this study, we report a simple, scalable, and cost-effective fabrication strategy in which hydrothermally synthesized WS 2 microsheets are uniformly integrated onto a commercially available poly(vinyl alcohol) (PVA) sponge to construct a three-dimensional porous photothermal evaporator. The unique WS 2 /PVA architecture synergistically combines the excellent photothermal properties of WS 2 with the intrinsic hydrophilicity and interconnected water-transport channels of the PVA sponge, resulting in efficient thermal localization and continuous water supply. The optimized 3 wt % WS 2 /PVA evaporator exhibited excellent broadband solar absorption (85.48%) across the UV–visible–NIR region and achieved a high photothermal conversion efficiency of 96.82%. Under solar light illumination, the optimized WS 2 /PVA evaporator delivered an evaporation rate of 2.78 kg m –2 h –1, representing the highest reported performance among WS 2 -based ISSG materials. This value surpasses those of previously reported CS/WS 2 (2.10 kg m –2 h –1 ) and WS 2 –O-graphene (2.11 kg m –2 h –1 ) systems and is substantially higher than that of pristine PVA (0.37 kg m –2 h –1 ). The enhanced performance is attributed to the reduced evaporation enthalpy (1398 kJ kg –1 ), excellent hydrophilicity (water contact angle 19.1°), and strong interfacial hydrogen-bonding interactions between WS 2 and PVA, which collectively facilitate rapid water transport and efficient heat confinement. Furthermore, the evaporator demonstrated excellent operational stability over 10 consecutive cycles without observable salt accumulation during 8 h of continuous operation. Desalination experiments using real seawater collected from Dwarka achieved an evaporation rate of 2.58 kg m –2 h –1, with the conductivity decreasing from 37.9 mS cm –1 to 823 μS cm –1 confirming effective salt rejection. These findings demonstrate that the 3D WS 2 /PVA photothermal evaporator provides a low-cost, scalable, and environmentally sustainable platform for high-efficiency solar desalination and freshwater production.