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.

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.