A Three-Level Biomimetic Evaporation System Inspired by Root-Stem-Leaf for High-Performance Solar Desalination

Abstract

Solar-driven interfacial evaporation offers a promising route to mitigate global freshwater shortage scarcity. Nevertheless, achieving efficient management of water, salt, and heat remains a critical challenge in designing photothermal evaporation systems. Inspired by the hierarchical structure of tree root–stem–leaf systems, we propose a three-level biomimetic strategy to fabricate a trilevel photothermal fibrous membrane that enables highly efficient and stable solar desalination of seawater. This membrane features a spatially and functionally decoupled architecture: a hydrophilic polyacrylonitrile (PAN) fibrous substrate serves as a root-like layer for rapid water uptake; a sulfobetaine methacrylate (SBMA)-modified PAN (PAN@SBMA2) intermediate layer mimics stem vasculature, synergistically regulating water retention and salt rejection through strong hydration and electrostatic screening; and a 2.0 wt% of molybdenum sulfide (MoS2) loaded polyvinylidene fluoride (PVDF) (2.0MoS2@PVDF) top layer acts as a leaf-inspired photothermal zone for localized solar–thermal conversion and vapor generation. Benefitting from the synergistic water-salt-heat enhancement afforded by this ‘root-stem-leaf’ cooperative interlayer design, the resulting 2.0MoS2@PVDF-PAN@SBMA2-PAN (2.0MP-PS2-P) membrane achieves a high evaporation rate and an efficiency. This work not only presents an efficient solar-driven evaporation membrane for solar desalination but also demonstrates a systematic biomimetic structure paradigm for synergistic resource management in interfacial evaporation systems.