Efficient Fabrication of Micro/Nanostructured Polyethylene/Carbon Nanotubes Foam with Robust Superhydrophobicity, Excellent Photothermality, and Sufficient Adaptability for All‐Weather Freshwater Harvesting

Abstract

The integration of fog collection and solar‐driven evaporation has great significance in addressing the challenge of the global freshwater crisis. Herein, a micro/nanostructured polyethylene/carbon nanotubes foam with interconnected open‐cell structure (MN‐PCG) is fabricated using an industrialized micro extrusion compression molding technology. The 3D surface micro/nanostructure provides sufficient nucleation points for tiny water droplets to harvest moisture from humid air and a fog harvesting efficiency of 1451 mg cm−2 h−1 is achieved at night. The homogeneously dispersed carbon nanotubes and the graphite oxide@carbon nanotubes coating endow the MN‐PCG foam with excellent photothermal properties. Benefitting from the excellent photothermal property and sufficient steam escape channels, the MN‐PCG foam attains a superior evaporation rate of 2.42 kg m−2 h−1 under 1 Sun illumination. Consequently, a daily yield of ≈35 kg m−2 is realized by the integration of fog collection and solar‐driven evaporation. Moreover, the robust superhydrophobicity, acid/alkali tolerance, thermal resistance, and passive/active de‐icing properties provide a guarantee for the long‐term work of the MN‐PCG foam during practical outdoor applications. The large‐scale fabrication method for an all‐weather freshwater harvester offers an excellent solution to address the global water scarcity.

Superhydrophobic coating with a micro- and nano-sized MnO2/PDMS composite structure for passive anti-icing/active de-icing and photothermal applications

“…In particular, functional coatings inevitably work in complex environments, such as small-particle erosion or rainfall impact, in practical applications. 54–56 Therefore, a series of tests (resistance to sandstone impact, water-current impact, corrosion by acid, alkali and salt solution, sandpaper abrasion, and high/low temperature variations) were undertaken (Fig. 3g–i and Fig.…”

Overview of the design of bionic fine hierarchical structures for fog collection

“…146 Therefore, the direct design of 3D HS is important for practical applications. 147,148 However, in addition to being driven by Laplace pressure differences, wettability gradients, and capillary forces, the principle of designing 3D HS for fog collection is often driven by gravity. 149 Gravity-driven HS are often designed with an open surface, which increases the risk of the evaporation of the collected fog.…”

Anisotropic MXene/Poly(vinyl alcohol) Composite Hydrogels with Vertically Oriented Channels and Modulated Surface Topography for Efficient Solar-Driven Water Evaporation and Purification

“…Huang et al demonstrated that the design of vertically aligned channels in an aerogel evaporator can reduce heat loss and promote water transport at gas–liquid interfaces, thus achieving enhanced evaporation efficiency . Additionally, appropriate surface design has also been shown to improve water evaporation performance. , Zhu et al designed a water lily inspired evaporator with a hydrophobic surface, avoiding the accumulation of salt crystals on the surface and achieving a better brine desalination performance than a conventional hydrophilic evaporator . Yu et al constructed a PVA hydrogel with a sharply dimpled surface to increase heat flux, promote water diffusion, and thus achieve a high solar steam generation performance .…”