Bioinspired Mossene Membrane Integrating Sulfhydryl-Modified MOFs for Efficient Solar-Driven Seawater Desalination

Abstract

A fundamental challenge in the design of solar evaporators is balancing the conflicting requirements of salt rejection and high evaporation efficiency. Consequently, bioinspired membrane design has emerged as a promising strategy for enhancing solar-driven interfacial water evaporation and desalination. Here, we report a bioinspired asymmetric photothermal membrane that is denoted as Mossene. Its design is inspired by the ecological water-regulation strategies of niche bryophytes. This Mossene membrane integrates dual-layer functionality: a hydrophilic substrate for water transport and retention and a hydrophobic top layer for light absorption and floatation. The lower hydrophilic layer is fabricated by electrospinning polyamide-6 blended with a sulfhydrylated UiO-66 metal–organic framework. This structure enables rapid water uptake, storage, and sustained molecular transport, emulating the function of water-storage cells in bryophyte leaves. The upper hydrophobic layer, composed of multiwalled carbon nanotubes and polyvinylidene fluoride, replicates the surface hydrophobicity and chlorophyll-mimetic light-harvesting characteristics of moss leaves. This design ensures efficient solar absorption and thermal confinement. Under 1 kW m^–2 irradiation, the dry surface of Mossene heats from 16 to 109.9 °C within 6 min. When floated on 3.5 wt % NaCl solution, the membrane reaches 78.5 °C in 5 min, demonstrating excellent photothermal conversion. The optimized Mossene membrane (MCM-6.5–0.75) achieves an outstanding water evaporation rate of 1.55 kg m^–2 h^–1 and an energy conversion efficiency of 97.5%. This study introduces Mossene as a biomimetic photothermal membrane that integrates hierarchical structure, selective wettability, and efficient energy utilization and underscores the potential of next-generation solar evaporators for practical implementation in sustainable water purification.