A biomimetic leaf epidermis: Moldable knitted fabric based carbon fiber evaporator using weaving process for stable solar water desalination

Abstract

The growing global demand for freshwater has driven the development of solar interfacial evaporation as an energy-efficient desalination strategy. In this work, a biomimetic carbon fiber–tencel mixed fabric evaporator is developed by mimicking the leaf epidermis in terms of directional water transport and light harvesting using a conventional weaving process. Carbon fibers act as an efficient broadband photothermal layer, while hydrophilic tencel provides continuous capillary-driven water transport, forming a coating-free and structurally tunable system via weave architecture. By varying the weave architecture, the light absorption, moisture transport, and evaporation behavior can be directly controlled at the textile level. The performance is supported by multi-scale characterization. Scanning electron microscopy analysis shows aligned carbon filaments (∼7–10 μm) and porous tencel fibers (∼10–15 μm), enabling effective heat localization and water supply. Water uptake reaches ∼35 g/g for tencel compared to ∼7 g/g for carbon fiber, confirming strong functional synergy. Optical measurements (350–1100 nm) and thermal imaging further demonstrate enhanced absorption and higher surface temperatures with increasing weave float length. The results show that the optimized 4:1 twill structure achieves an evaporation rate of 4.95 kg m −2 h −1 under 1 sun (1 kW m −2 ), significantly higher than pure water (∼1.80 kg m −2 h −1 ), while maintaining stable operation through localized salt crystallization without surface blockage. These findings demonstrate that textile architecture alone can govern heat and mass transfer without additional chemical modification. This study introduces a scalable, coating-free, biomimetic textile evaporator, offering strong potential for desalination, wastewater treatment, and zero-liquid discharge systems, as well as broader applications in photothermal and energy–water integrated materials.