A High-Performance Passive Radiative Cooling Metafabric with Janus Wettability and Thermal Conduction.

With the development of industry and global warming, passive radiative cooling textiles have recently drawn great interest owing to saving energy consumption and preventing heat-related illnesses. Nevertheless, existing cooling textiles often lack efficient sweat management capacity and wearable comfort under many practical conditions. Herein, a hierarchical cooling metafabric that integrates passive radiation, thermal conduction, sweat evaporation, and excellent wearable comfort is reported through an electrospinning strategy. The metafabric presents excellent solar reflectivity (99.7%, 0.3-2.5 µm) and selective infrared radiation (92.4%, 8-13 µm), given that the unique optical nature of materials and wettability gradient/micro-nano hierarchical structure design. The strong moisture-wicking effect (water vapor transmission (WVT) of 2985 g m-2 d-1 and directional water transport index (R) of 1029.8%) and high heat-conduction capacity can synergistically enhance the radiative cooling efficiency of the metafabric. The outdoor experiment reveals that the metafabric can obtain cooling temperatures of 13.8 °C and 19.3 °C in the dry and sweating state, respectively. Meanwhile, the metafabric saves ≈19.3% of annual energy consumption compared with the buildings with HAVC systems in Shanghai. The metafabric also demonstrates desirable breathability, mechanical strength, and washability. The cost-effective and high-performance metafabric may offer a novel avenue for developing next-generation personal cooling textiles.

Asymmetrical Emissivity and Wettability in Stitching Treble Weave Metafabric for Synchronous Personal Thermal-Moisture Management.

Developing textiles with passive thermal management is an effective strategy to maintain the human body healthy as well as decrease energy consumption. Personal thermal management (PTM) textiles with engineered constituent element and fabric structure have been developed, however the comfortability and robustness of these textiles remains a challenge due to the complexity of passive thermal-moisture management. Here a metafabric with asymmetrical stitching treble weave based on woven structure design and yarn functionalization is developed, in which the thermal radiation regulation and moisture-wicking can be achieved simultaneously throughout the dual-mode metafabric due to its optically regulated property, multi-branched through-porous structure and surface wetting difference. With simply flipping, the metafabric enables high solar reflectivity (87.6%) and IR emissivity (94%) in the cooling mode, and a low IR emissivity of 41.3% in the heating mode. When overheating and sweating, the cooling capacity reaches to ≈9 °C owing to the synergistic effect of radiation and evaporation. Moreover, the tensile strengths of the metafabric are 46.18 MPa (warp direction) and 37.59 MPa (weft direction), respectively. This work provides a facile strategy to fabricate multi-functional integrated metafabrics with much flexibility and thus has great potential for thermal management applications and sustainable energy.

Thermodynamically Induced Interfacial Condensation for Efficient Fog Harvesting.

Fog harvesting is a sustainable approach to dealing with the global freshwater crisis. A range of strategies in microstructure design and wettability remodeling for fog management are clearly explained. However, the influence of thermodynamic endothermic and exothermic processes on fog harvesting is rarely explored. Here, a thermodynamically induced interfacial condensation-enhanced fog-harvesting fabric (AWF-6) is developed that also incorporates asymmetric geometry and surface chemistry. By coupling the high thermal conductivity interface supported by boron nitride nanosheets (BNNS), the Laplace pressure difference generated by nanoneedles, and the wettability gradient constructed by stearic acid (STA), the fabric achieves a water collection rate (WCR) of 1538.4 mg h cm-2 , which is the maximum value in state-of-the-art cotton-based fog harvesting devices (FHDs). Furthermore, the potential application of AWF-6 in agricultural irrigation is demonstrated. This study shows a thermodynamic proposal for building next-generation fibrous FHDs.

Fabrication of Hydrophobic Poly(vinylidene fluoride) Membranes with Manipulated Micromorphology and Enhanced Strength.

In this work, an ethanol/water/glycerol ternary coagulation bath system was used to fabricate a hydrophobic PVDF membrane, which will have a considerable impact on the micromorphology. This change will further affect the performance of the membrane. After introducing glycerol into the coagulation bath, the precipitation process was finely regulated. The obtained results implied that glycerol could inhibit solid-liquid separation and promoted liquid-liquid separation. A pleasant discovery was that the mechanical properties of the membrane were improved because of the more fibrous polymers formed by liquid-liquid separation. Besides, a more uniform pore size can be achieved. A fascinating symmetrical interconnected fibrous and spherulitic structure was depicted by membranes fabricated with a coagulation bath consisting of 6% water, 34% ethanol, and 60% glycerol. This membrane had a high water contact angle of 146.6° and a small mean pore size of 0.46 µm. Enhanced tensile strength and elongation at break evidenced that the membrane enjoyed good robustness and flexibility. This facile approach provided the possibility to prepare membranes with tailored pore size and the required strength.

A facile and green route to fabricate fiber-reinforced membrane for removing oil from water and extracting water under slick oil.

Except the good separation performance, the membranes used for oil-water mixture separation should be fabricated with as little wastewater produced as possible. Thus, we proposed a green tactic--water vapor induced phase inversion to prepare the high-strength and superhydrophilic/underwater superoleophobic nonwoven fabric-based cotton/PA6/PAN membranes which is based on the polymer/solvent/nonsolvent ternary system analysis. Differing from adding additives in polymer solution or coagulation bath, above proposed strategy has an "subtractive effect" with the advantages of constructing three-dimensional porous structure and greatly reducing the organic wastewater produced during preparation process. Moreover, the obtained cotton/PA6/PAN membranes exhibited unexpected performances for separating oil-in-water emulsions. An ultrahigh permeation flux of up to 478,000 L m-2 h-1 bar-1 with a separation efficiency of > 99.9% was obtained under the driving pressure of 1.6 KPa, which was one order of magnitude higher than the conventional separation membranes with similar properties. In addition, it is surprising that the cotton/PA6/PAN membranes can also extract water from the slick oil/water immiscible mixture. Therefore, it is expected that the cotton/PA6/PAN membranes can be used in practical oily wastewater purification.

Synthesis of zinc sulfide/copper sulfide/porous carbonized cotton nanocomposites for flexible supercapacitor and recyclable photocatalysis with high performance.

The composite material composed of zinc sulfide, copper sulfide and porous carbon is prepared in this study, exhibiting excellent performances in the field of supercapacitor electrode and photocatalysts. In the degradation process of organic pollutants, zinc sulfide/copper sulfide with heterostructure effectively reduce the recombination rate of photo-generated electron-hole pairs. And the porous carbon substrate can not only accelerate the separation of photo-carriers but also provide numerous active sites. Furthermore, the sample can be easily separated after decomposing the organic pollutants. As a supercapacitor electrode, the combination of zinc sulfide/copper sulfide with large pseudo-capacitance and porous carbon material with excellent double-layercapacitance results in superior electrochemical performances. The composite electrode shows a high specific capacitance of 1925 mF cm-2/0.53 mAh cm-2 at 4 mA cm-2. And the symmetric flexible supercapacitor based on the composite electrode achieves an outstanding energy density (0.39 Wh cm-2 at the power density of 4.32 W cm-2). Therefore, the zinc sulfide/copper sulfide/porous carbonized cotton nanocomposites (pCZCS) prepared herein exhibit dual functions of photocatalysts with high efficiency as well as energy storage materials with high energy density, which is interesting and important for expanding the practical applications in cross fields.