Multiscale Biomimetic Evaporators Based on Liquid Metal/Polyacrylonitrile Composite Fibers for Highly Efficient Solar Steam Generation

Solar steam generation (SSG) offers a cost-effective solution for producing clean water by utilizing solar energy. However, integrating effective thermal management and water transportation to develop high-efficiency solar evaporators remains a significant challenge. Here, inspired by the hierarchical structure of the stem of bird of paradise, a three-dimensional multiscale liquid metal/polyacrylonitrile (LM/PAN) evaporator is fabricated by assembling LM/PAN fibers. The strong localized surface plasmon resonance of LM particles and porous structure of LM/PAN fibers with interconnected channels lead to efficient light absorption up to 90.9%. Consequently, the multiscale biomimetic LM/PAN evaporator achieves an outstanding water evaporation rate of 2.66 kg m^-2 h^-1 with a solar energy efficiency of 96.5% under one sun irradiation and an exceptional water rate of 2.58 kg m^-2 h^-1 in brine. Additionally, the LM/PAN evaporator demonstrates a superior purification performance for seawater, with the concentration of Na⁺, Mg²⁺, K⁺ and Ca²⁺ in real seawater dramatically decreased by three orders to less than 7 mg L^-1 after desalination under light irradiation. The multiscale LM/PAN evaporator with hierarchical structure regulates the water transportation as well as thermal management for highly effective solar-driven evaporation, providing valuable insight into the structural design principles for advanced SSG systems.