Bioinspired Spider Silk Fiber of MOF-Based Zwitterionic Hydrogel for Low-Humidity Atmospheric Water Harvesting

Abstract

A bioinspired spider silk fiber (i.e., PCLC) is presented by introducing the zwitterionic hydrogel poly-[2-(methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide (PDMAPS) and CAU-10-H used as carriers of hygroscopic salt Lithium chloride (LiCl), and the addition of carbon black (CB) nanoparticles makes the prepared fibers have photothermal effect. PCLC fiber achieves the moisture absorption capacity of ≈1.49 – 1.99 g g⁻¹ after 2 h adsorption at ≈40% relative humidity (RH). The temperature of a single PCLC knot can rise to 46.4 °C for ≈3600 s, and the temperature of a batch of PCLC spider knot fibers can rise to 112.1 °C for ≈3600 s (under ≈1 sun illumination), which has excellent photothermal effect. Water collection is conducted for five consecutive days with a daily collected amount of ≈1.87 g g⁻¹. The PCLC fiber shows good water vapor adsorption reversibility after 10 consecutive adsorption-desorption cycles, the moisture absorption can be stabilized at ≈1.9 g g⁻¹, and the water vapor desorption capacity reaches ≈1.73 g g⁻¹ (under ≈1 sun illumination, exhibiting water vapor desorption efficiency of ≈92.1%).