Leveraging Hydrophilic Hierarchical Channels to Regulate Excessive Water for High-Efficiency Solar Steam Yield.

Both the solar absorptance and water content in solar-driven interface evaporation (SDIE) devices are of equal importance for efficient solar steam yield and freshwater production, but water content regulation has garnered relatively less attention, as it is more challenging to balance the water supply rate and the evaporation rate inside SDIE devices. Herein, an SDIE device is designed by coating natural luffa with polypyrrole, which could effectively regulate the water content during the solar steam yield by its unique hydrophilic hierarchical channels to transform excessive water from the bulk state into the film state on the porous skeleton. The hierarchical channels revealed by cryoelectron microscopy experiments not only reduce the loss of heat in unevaporated water but also offer abundant escape channels for solar steam, thus enabling the proposed SDIE device to achieve an evaporation rate of 2.38 kg m-2 h-1 under 1 sun illumination. This work reveals the key role of hierarchical channels for water regulation in the high-efficiency solar steam yield and triggers further application of natural biomaterials with unique structures in the field of solar interfacial evaporation.

Magnetically Driven Tunable 3D Structured Fe3 O4 Vertical Array for High-Performance Solar Steam Generation.

Structural design of the solar-absorbing layer has been considered as one of the most direct and effective approaches for improving the solar steam generation performance by maximizing the absorption of sunlight, but great challenges in manipulation simplification and structure controllability still remain. Herein, a polyester (PET) fabric covered with a vertically aligned 3D tower-like ferrosoferric oxide (Fe3 O4 ) array via a convenient magnetically driven spray-coating method is reported, and both the spatial density and height of the Fe3 O4 array are tunable upon spraying time. It shows an extremely high solar absorbance (98.6%) in the entire solar spectrum, which is superior to the corresponding 2D Fe3 O4 structure (91.1%). Combining the obtained 3D Fe3 O4 /PET with a yolk-shell hydrophobic/superhydrophilic modified melamine-formaldehyde (mMF) sponge, the carefully designed and fabricated 3D Fe3 O4 /PET-mMF evaporator can realize a high water evaporation rate of 1.59 kg m-2 h-1 under 1 kW m-2 solar illumination, outperforming most related solar steam generation systems. With the advantages of cost-effectiveness, high evaporation rate, reliable endurance, and structural controllability, this 3D structural design provides an avenue to build up high-performance solar energy-driven water steam generation systems.

Efficient Removal of Dye from Wastewater without Selectivity Using Activated Carbon-Juncus effusus Porous Fibril Composites.

Adsorption techniques have been successfully applied in water purification because of their flexibility, simplicity of design, and effectiveness. Activated carbon is an effective absorbent using for dye adsorption; however, the powder structure is not conducive for practical applications and cannot be used to filter dye solutions which are challenges that still need to be addressed. Herein, a natural cellulose-based absorbent, activated carbon-Juncus effusus fiber (AC-JE fiber), demonstrates the removal of all kinds of dyes without selectivity and humic substances and humic-like organics from wastewater. The combined macroporous structures of JE fibers and the microporous and mesoporous structures of activated carbon particles enhance their adsorption properties. These composite absorbents have excellent adsorption and continuous filtration effect. The rejection rate is approximately 100% not only on acidic and anionic dyes but also on basic and cationic dyes. Moreover, the dye solution adsorbed by AC-JE fibers exhibits an ideal freshwater quality (almost no bacteria), similar to that of the deionized water. The AC-JE fibers prove their potential for dye removal, in both adsorption and filtration. Their sterilization ability substantiates their potential in the field of water purification as they can be used as ideal absorbents based on cellulose for removing dyes and purifying wastewater.

Blackbody-Inspired Array Structural Polypyrrole-Sunflower Disc with Extremely High Light Absorption for Efficient Photothermal Evaporation.

The three-dimensional (3D) structural design of solar evaporators has been considered as one of the most promising approaches toward enhancing photothermal performance by improving light absorption and the available evaporation area. Herein, polypyrrole-decorated 3D array structural sunflower discs (PPy-SFD) were prepared for solar steam generation, thereby turning SFD biomass waste into valuable materials. The SFD can absorb a majority of the incident light because of numerous light reflections from each natural 3D array structural unit, and therefore behaves similar to a blackbody. Moreover, a facile pyrrole polymerization method was introduced to further improve SFD light absorption and enhance the photothermal performance of SFD. This circumvents expensive consumption fabrication processes. The black PPy-decorated SFD shows a light absorption of 99.3% across the entire solar spectrum coupled with mechanical stability. During photothermal evaporation, the increased evaporation area of the 3D array structural SFD could effectively reduce heat loss to the environment because the inherent microporous structure of the SFD leaves and cellulose hydrophilicity provide channels for water transport. The PPy-SFD-based evaporator could reach an evaporation rate of 1.74 kg m-2 h-1 under 1 sun. Thus, the 3D array structural PPy-SFD is a possible candidate for high-efficiency photothermal evaporators.

Polyphenylene Sulfide Ultrafine Fibrous Membrane Modified by Nanoscale ZIF-8 for Highly Effective Adsorption, Interception, and Recycling of Iodine Vapor.

In this study, two novel composite membranes containing nanoscale ZIF-8 and polyphenylene sulfide (PPS) nonwoven fabric were prepared via hydrothermal (PPS-ZIF-8) and biomimetic mineralization (PPS-ZIF-8-BSA; BSA, bovine serum albumin) approaches. The biomimetic mineralization approach in particular was extremely rapid and mild, and crystalline ZIF-8 was coated on the PPS substrate in only a few seconds at room temperature. The maximum iodine adsorption capacities of the PPS-ZIF-8 and PPS-ZIF-8-BSA membranes were 2.51 and 2.07 g/g, respectively. The composite fibrous membranes were able to capture trace iodine vapor under differential pressures ranging from 0 to 1000 Pa without almost any iodine vapor leakage. The composite membranes can be applied in harsh environments because of the excellent stability of ZIF-8 and the PPS high-performance fibers. This study provides a promising strategy to fabricate novel adsorption materials for the collection of radioactive iodine during nuclear waste disposal.