Hydrophobic sodium alginate/montmorillonite/CNTs composite hydrogel for simultaneous efficient solar-driven interfacial evaporation and suppressed salt deposition

A SA/MMT/CNT hydrogel enables efficient solar-driven interfacial evaporation. • MMT regulates water states to promote interfacial water evaporation. • Fluorinated interfacial engineering effectively suppresses salt crystallization. • MD simulations reveal hydrogen-bond evolution and interfacial ion exclusion. Conventional desalination system suffers from high energy consumption and complicated equipment combination. Solar driven interfacial evaporation offers great potential for next-generation desalination since it is only driven by solar energy, and its system efficiency is substantially high. However, achieving a balance of strong light absorption, structural stability and long-term salt tolerance in a single solar evaporator is still a big challenge. This work, therefore, proposes a sodium alginate /montmorillonite/carbon nanotube (SA/MMT/CNTs) composite hydrogel for efficient solar-driven interfacial evaporation. By integrating a broadband photothermal CNTs network with low cost and hydroxyl-rich MMT nanosheets, the composite system simultaneously achieves enhanced solar light absorption and accelerated water evaporation. To further improve the anti-salt performance of the prepared composite hydrogel, a hydrophobic surface modification method with silane coupling modification strategy is introduced. And molecular dynamics (MD) simulations provide molecular-level insights into the evolution of molecular configuration and hydrogen bond density, ion distribution, thereby revealing the underlying mechanisms responsible for the improved anti-salt performance. The resulting composite hydrogel based solar evaporator delivers an evaporation rate of 1.76 kg m −2  h −1 under one-sun irradiation. In addition, it exhibits excellent long-term stability and strong resistance to salt accumulation under salt solution. Outdoor experiment in Xining City, Qinghai province is preformed to verify the practical potential of the composite hydrogel based solar evaporator. This study provides a low-cost and effective strategy for high-performance solar desalination systems. Download: Download high-res image (372KB) Download: Download full-size image