Versatile GO/ANFs Aerogel for Highly Efficient Solar-Powered Water Purification in Wide Environments.

Solar-driven interfacial evaporation is a very promising choice for producing clean water. Despite the considerable investigation of pure NaCl brine purification, solar-driven complex water purification, such as real-world seawater desalination as well as domestic and industrial wastewater treatment, has rarely been investigated, mainly due to its compositions being much more complicated than NaCl brine. Herein, we developed a graphene oxide/aramid nanofiber (GO/ANFs) aerogel by a freeze-drying process. The GO/ANFs aerogel combined opened porous microchannels, superhydrophilicity, anti-oil-fouling capacity, enhanced broad-spectrum light absorption (more than 92%), and good solar/heat management. These integrated properties enabled the GO/ANFs aerogel to be an advanced solar interfacial evaporator for efficient freshwater production with the characteristics of localized heat conversion, quick water transport, and salt crystallization inhibition, and the rate of steam production rate was as high as 2.25 kg m-2 h-1 upon exposure to 1 solar irradiation. Importantly, the high-water-vapor generation rate was maintained even under complicated conditions, including real-world seawater, dye water, emulsions, and corrosive liquid environments. Considering its promising adaptability to a wide range of environments, this work hopes to inspire the development of brine desalination, wastewater purification, clean water production, and solar energy utilization.

Mechanical Robust GO/PVA Hydrogel for Strong and Recyclable Adhesion in Air, Underwater, and Underoil Environments.

Adhesive hydrogels are considered to be promising interfacial adhesive materials for various applications; however, their adhesive strength is significantly reduced when immersed in liquid environments (water and oil) due to obstruction of the liquid layer or swelling in liquid, and they could not always be reused when the failure of the adhesive performance occurred. Herein, a graphite oxide/poly(vinyl alcohol) (GO/PVA) hydrogel with strong adhesion in air and under liquid environments was developed by rationally regulating the interactions of water and dimethyl sulfoxide (DMSO) in the binary liquid system. The strong interaction between water and DMSO allowed the water layer of the GO/PVA hydrogel on the hydrogel surface to act as a shield to repel oil in air, under water, and even when immersed in oil, and it also endowed the obtained hydrogel with antiswelling property when immersed in water and oil. Importantly, the GO/PVA hydrogel could serve as an advanced adhesive to firmly bond different substrates in air, under water, and under oil, and interestingly, its dry and wet adhesive performance was repeatable and recyclable. This work is expected to be an important addition to the field of adhesive soft materials.

Simple and Rapid Way to a Multifunctionally Conductive Hydrogel for Wearable Strain Sensors.

Conductive hydrogels have gained increasing attention in the field of wearable smart devices. However, it remains a big challenge to develop a multifunctionally conductive hydrogel in a rapid and facile way. Herein, a conductive tannic acid-iron/poly (acrylic acid) hydrogel was synthesized within 30 s at ambient temperature by the tannic acid-iron (TA@Fe3+)-mediated dynamic catalytic system. The TA@Fe3+ dynamic redox autocatalytic pair could efficiently activate the ammonium persulfate to initiate the free-radical polymerization, allowing the gelation to occur easily and rapidly. The resulting hydrogel exhibited enhanced stretchability (3560%), conductivity (33.58 S/m), and strain sensitivity (gauge factor = 2.11). When damaged, it could be self-healed through the dynamic and reversible coordination bonds between the Fe3+ and COO- groups in the hydrogel network. Interestingly, the resulting hydrogel could act as a strain sensor to monitor various human motions including the huge movement of deformations (knuckle, wrist) and subtle motions (smiling, breathing) in real time due to its enhanced self-adhesion, good conductivity, and improved strain sensitivity. Also, the obtained hydrogel exhibited efficient electromagnetic interference (EMI) shielding performance with an EMI shielding effectiveness value of 24.5 dB in the X-band (8.2-12.4 GHz). Additionally, it displayed antibacterial properties, with the help of the activity of TA.

Constructing of efficient interface solar evaporator: In-situ colloid foaming strategy for solar desalination and visible light response sewage purification.

The shortage of drinking water has become a global problem, coastal cities can make full use of abundant seawater resources by desalination technology to ease the contradiction between supply and demand. However, fossil energy consumption contradicts the goal of reducing carbon dioxide emissions. Currently, researchers favor interfacial solar desalination devices relying only on clean solar energy. Based on the structure optimization of the evaporator, a kind of device composed of a superhydrophobic BiOI (BiOI-FD) floating layer and CuO polyurethane sponge (CuO sponge) is constructed in this paper, with its design advantages presented in the following two aspects: 1. The novel BiOI-FD photocatalyst in the floating layer reduces the surface tension and realizes the degradation of the enriched pollutants, ensuring the device to achieve solar desalination and inland sewage purification; 2. CuO sponge can inhibit salt crystallization and realize the combination of the water transport and photothermal layers. Particularly, the photothermal evaporation rate of the interface device reached 2.37 kg m-2 h-1.The novel interface evaporator design will bring a new solution for solar desalination, sewage treatment and large-scale application.

Tree-Inspired Aerogel with a Radial and Centrosymmetric Structure for Efficient Solar-Powered Water Purification.

Solar-powered water purification is one of the promising choices for clean water production. However, it remains challenging to develop aerogel solar evaporators that simultaneously possess enhanced light-to-heat conversion, optimal thermal management, and salt crystal deposition inhibition. Herein, to address this challenge, we have developed a 3D chitosan-reduced graphene oxide/polypyrrole (CS-RGO/PPy) aerogel vaporizer with a vertical and radially aligned structure through a directional freezing process, inspired by the featured structure of conifers. The radially porous walls and vertically arranged channels within the 3D aerogel were able to facilitate high light absorption, localizing converted heat, rapid water transport, and self-salt discharge. Under 1 sun irradiation, the aerogel vaporizer displayed an improved light absorption characteristic of 95% and a high-rate evaporation (∼3.19 kg m-2 h-1) that achieved continuous freshwater from the saturated brine production without solid salt crystallization. Besides achieving seawater desalination, the obtained aerogel could purify organic wastewater and emulsions through solar distillation with high-rate continuous water production.

Design of an interface heating device based on polydivinylbenzene/SiO2/Bi2WO6 and its visible light response performance for water purification.

Environmental pollution and the shortage of drinking water are the challenges that mankind is facing. Solar interface evaporation technology has been demonstrated as an important method for producing clean water, but its application to sewage still faces problems, mainly manifested in solubility and oily pollutants. Therefore, an evaporator device contains a superhydrophobic Bi2WO6 felt floating layer, a filter paper hydrophilic layer, and a copper foam/CuO photothermal layer, of which the water contact angle of the superhydrophobic felt can reach 159°. The floating layer not only has the ability to adsorb n-hexane but the Rh B degradation can also be realized under indoor/outdoor light conditions. The carrier life of Bi2WO6 is 28.8 ns. A copper foam/CuO photothermal layer prepared through a low-temperature treatment is combined with the floating and hydrophilic layer to obtain an evaporation rate of 1.53 kg m-2 h-1.

Design of Superhydrophobic CoFe2O4 Solar Seawater Desalination Device and Its Application in Organic Solvent Removal.

Environmental pollution and clean water production are challenges to the development of human society. In this paper, devices consisting of a superhydrophobic Ni-CoFe2O4 foam layer (floating layer), a hydrophilic channel and a superhydrophilic Ni-CoFe2O4 foam layer (photothermal conversion layer) were designed. The light energy was converted into heat on the photothermal layer, for which the hydrophilic channel provided a small amount of water. The superhydrophobic layer ensured the floating and selective adsorption of organic solvents on the water surface, whose contact angle reached 157°, and the steam production rate reached 1.68 kg·m-2·h-1. Finally, the LSV curve demonstrated that the Ni-CoFe2O4 foam prepared had a minimum starting potential, achieving the multifunctionality of the Ni foam.

Ag/polydopamine-coated textile for enhanced liquid/liquid mixtures separation and dye removal.

Engineering a versatile platform that enables to separate both oil/water and oil/oil mixtures and remove dye from water is not easy. To address this challenge, we have developed an Ag/polydopamine-coated textile (Ag/PDA@textile) by chemically depositing Ag particles on the textile surface using polydopamine as the binder layer. The obtained Ag/PDA@textile attracts water but repels oil in the air, underwater, and when immersed into the oil. Exploiting its water-attracting and oil resistance, the Ag/PDA@textile is acted as a separation membrane to separate oil/water mixtures with enhanced separation efficiency. The Ag/PDA@textile also possesses opposite wetting behavior to oils with different polarities, allowing it to separate oil/oil mixtures efficiently. Thanks to the catalytic performance of the Ag particle, organic dyes can be decomposed effectively by our Ag/PDA@textile under UV illustration or in the presence of NaBH4. Our Ag/PDA@textile may be valuable for applications in water purification and oil sewage treatment.

Versatile superhydrophobic bismuth molybdate cotton fabric for oil/water separation and decompose dyestuff.

Water pollution caused by the discharged insolubility petroleum contaminants and organic compound dyes seriously threatens the natural self-purity capacity of the water body and the survival of aquatic species, so it is imperative to restraint the deterioration of the aquatic environment. In this paper, pathways are propounded for the simultaneous removal of insoluble spilling oil and organic dye contaminants. Particularly, hydrophobic ZnSnO3 after stearic acid modification and Bi2MoO6 photocatalysts are introduced into the cotton fabric substrate through solution dip-coating. The durability of the prepared fabric suffers from the acid-base corrosion, thermal treatment and mechanical wear, while still exhibiting remarkable water-repellent (WCA > 150°) property. Furthermore, the remarkable photocatalytic activity makes it possible for reusable degradation and the primary active species, namely the holes, to be verified by the radicals-capturing experiment. It is worth observing that as-prepared superhydrophobic fabric possesses admirable water-proof property and cycling durability of decomposing toxic water-soluble organic dye, thereby contributing to further realizing the ecological concept of clear waters.

Fabrication of visible-light response cadmium sulfide modified superhydrophobic surface for water resource remediation.

Widespread concern has been attached to the frequent occurrence of pollution by oil slicks and water-soluble pollutants in recent years. The semiconductor photocatalysis is applied to sewage treatment owing to the advantages of energy-conserving and environmental protection. However, its application is limited by the defects of not solving oil slicks and the hard recyclability. In this paper, the high specific surface area and rod-shaped CdS were prepared using template and alkali-treated methods. Next, the alkylated SiO2and alkali-treated CdS were deposited on pure fabric by physical deposition to prepare the multifunctional superhydrophobic fabric. The specific surface area and morphology of alkali-treated CdS were tested by BET specific surface area test and field emission scanning electron microscope. Besides, oil/water separation, water contact angle, and stability test experiments were performed to determine the superhydrophobic performance. Photocatalysis degradation efficiency and cycle degradation stability of multifunctional fabric were characterized by photocatalysis degradation Rh B experiment. Consequently, the alkali-treated CdS displays a high specific surface up to 343 m2g-1. The multifunctional fabric presents excellent superhydrophobic performance with the water contact angle up to 155°. Meanwhile, the water contact angle of multifunctional fabric is always over 150° under various circumstances (acid-base corrosion, soaking time at 100 °C and frictional numbers), indicating that the multifunctional fabric has excellent superhydrophobic stability. Moreover, the fabric also exhibits outstanding photocatalysis performance (the degradation efficiency is 94% after 3 cycles). Our work provides a feasible method for addressing oil slicks on water surface and degrading water-soluble pollutants with extensive application prospects in water resource remediation.

Superhydrophobic Self-Supporting BiOBr Aerogel for Wastewater Purification.

This research was focused on the raw material level construction of bismuth oxybromide (BiOBr) catalysis-loaded 3D cross-linked network polyurethane (PU) foam via the in situ polymerization method. After modification of superhydrophobic polydivinylbenzene nanoparticles, the PU foam possessed excellent superhydrophobic stability. The larger selective absorption oil phase capacity depended on its macroporous structure, and the existence of catalyst BiOBr (the band gap energy was about 2.57 eV) among the PU foam played a crucial role in degrading water-soluble contaminants under visible light irradiation. In this article, the photocatalytic experiment results verify that it has remarkable recycle degradation ability (the degradation efficiency can reach ∼97%) and the capture experiments indicate that the uppermost active species is h+.

Robust Hydrogel Coating with Oil-Repellent Property in Air, Water, and Oil Surroundings.

Development of a robust self-cleaning oil-repellent surface in a cost-efficient and green manner is highly desirable, yet still difficult to realize. Herein, we develop a poly(vinyl alcohol) (denoted as PVA) composite hydrogel on which the oily contaminations can be removed efficiently by water merely. Owing to its high affinity to water and resistance to oils, the water-wetted hydrogel establishes a slippery oil-repellent state in air, displays underwater superoleophobicity with ultralow adhesion to all probe oils, and blocks oil from permeating when immersed into an oil surrounding. Oily contaminations on the PVA hydrogel surface are removed just by titling or water immersion, with no oil residue left behind. This enhanced oil repellency was retained after hand-bending, water-jetting, and even 1000 cycles of sand abrasion, demonstrating mechanical robustness. Application of the PVA hydrogel-coated copper mesh is demonstrated to separate oil/water and oil/oil mixtures, with separation efficiency being greater than 98%.

Photocatalytically Active Superhydrophilic/Superoleophobic Coating.

Hydrophilic materials are easily fouled by organic contaminants owing to their high surface energy, and this oil-fouling problem severely hinders their use in practical applications. To address this challenge, herein, a hydrophilic coating with oil repellency and photocatalytic activity is developed by a spray-casting process. In the air surrounding, a water droplet spreads over the coating surface completely, while oil droplets exhibit contact angles more than 150° and moving on the coating freely. The water-wetted coating still had oil repellency, as the water layer on the coating surface can act as a lubricant to repel oil. Although methylene blue aqueous solution contaminates the coating by wetting it completely, these water-soluble organic molecules can be removed by UV illumination, due to the photocatalytic activity of the coating. Exploiting its water-attracting and oil-repelling properties, the coating deposited on a copper mesh is applied as a multiplatform for oil-water separation with high separation efficiency. This study provides a novel and efficient way to solve the oil-fouling problem of hydrophilic materials.

A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.

HYPOTHESIS: Development of an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding by a simple method is highly desirable, yet it remains a challenge that current technologies have been unable to fully address. EXPERIMENTS: Herein, the original fabric is immersed into the solution containing ZnO nanoparticle and PDMS (polydimethylsiloxane), and the fiber surfaces are uniformly covered by a ZnO-PDMS layer after thermal treatment at 110 °C for 30 min. FINDINGS: Droplets of water and corrosive liquids including strong acid, strong alkali, and saturated salt solution display sphere shape on the ZnO-PDMS coated fabric surface. The stable binding of ZnO-PDMS layer onto the fibers allows for the fabric coating with robust superhydrophobicity, and the coated fabric still displays superhydrophobicity after hand twisting, knife scratching, finger touching, and even cycles of sandpaper abrasion. The ZnO-PDMS coated fabric can also keep its superhydrophobic property when exposed to long term UV illumination, demonstrating its UV resistance. Moreover, the uniformly distribution of ZnO nanoparticles on fibers allows the ZnO-PDMS coated fabric to display UV shielding property.

Designing transparent superamphiphobic coatings directed by carbon nanotubes.

Creating surfaces with superamphiphobic property and optical transparency simultaneously would have fundamental and practical significance but has been proven extremely challenging. Herein, we develop a transparent superamphiphobic coating using carbon nanotubes (CNTs) as the template by a facile approach. CNTs enwrapped with SiO2 coating was produced by a sol-gel method and then sprayed onto the glass slides to form coatings. Subsequent thermal treatment and surface fluoration allowed the sprayed coating to exhibit enhanced transparency across a broad spectrum of ultraviolet and visible wavelengths and also display superrepellency toward water and a number of organic liquids, such as dodecane. The obtained transparent coating can sustain its superamphiphobicity even after thermal treatment at 400 °C. Separate experiment demonstrated that the CNTs-directed geometrical structure played a key role in establishing superamphiphobicity.