The Earth's atmosphere holds approximately 12 900 billion tons of fresh water distributed all over the world with fast replenishment. Atmospheric water harvesting is emerging as a promising strategy for clean water production in arid regions, land-locked areas, and remote communities. The water vapor sorbent is the key component for atmospheric water harvesting devices based on absorbing-releasing process. In this work, a flexible hybrid photothermal water sorbent composed of deliquescent salt and hydrogel was rationally fabricated. It possesses superior water sorption capacity even in low humidity air thanks to the deliquescent salt and maintains a solid form after it sorbs a large amount of water owing to the hydrogel platform. The harvested water could be easily released under regular sunlight via the photothermal effect, and it can be directly reused without noticeable capacity fading. An "easy-to-assemble-at-household" prototype device with 35 g of the dry hydrogel was tested outdoors under field conditions and delivered 20 g of fresh water within 2.5 h under natural sunlight. It is estimated that the material cost of making such a device to supply minimum daily water consumption for an adult (i.e., 3 kg) is only $3.20 (USD). This type of atmospheric water generator (AWG) is cheap and affordable, works perfectly with a broad range of humidity, does not need any electricity, and thus is especially suitable for clean water production in remote areas.

Colored cotton fabrics with satisfactory color fastness as well as durable antibacterial and self‐healing superhydrophobic properties are fabricated via a convenient solution‐dipping method that involves the sequential deposition of branched poly(ethylenimine) (PEI), silver nanoparticles (AgNPs), and fluorinated decyl polyhedral oligomeric silsesquioxane (F‐POSS) on cotton fabrics. The deposited AgNPs with tunable surface plasmon resonance endow the cotton fabrics with abundant color and and antibacterial ability. However, in general, water‐soluble AgNPs cannot be firmly deposited onto cotton fabrics to endure the laundering process. The integration of self‐healing superhydrophobicity into the cotton fabrics by depositing F‐POSS/AgNP/PEI films significantly enhances the color fastness of the AgNPs against laundry and mechanical abrasion, while retaining the antibacterial property of the AgNPs. The F‐POSS/AgNP/PEI‐coated cotton fabric accommodates an abundance of F‐POSS, which autonomically migrates to the cotton surface to repetitively restore its damaged superhydrophobicity. The self‐healing superhydrophobicity of the F‐POSS/AgNPs/PEI‐coated cotton fabric guarantees long‐term protection of the underlying AgNPs against laundry and abrasion and allows the cotton fabric to be cleaned by simple rinsing with water.

Clean water shortage has long been a challenge in remote and landlocked communities especially for the impoverished. Atmospheric water is now considered as an unconventional but accessible fresh water source and sorption-based atmospheric water generator (AWG) has been successfully demonstrated a reliable way of harvesting atmospheric water. The water vapor sorbents with high water uptake capacity and especially fast vapor sorption/desorption kinetics have become the bottleneck to a desirable clean water productivity in AWG. In this work, we developed a new nano vapor sorbent composed of a nano carbon hollow capsule with LiCl inside the void core. The sorbent can capture water vapor from ambient air as much as 100% of its own weight under RH 60% within 3 hours and quickly release the sorbed water within just half hour under 1 kW/m 2 sunlight irradiation. A batch-mode AWG device was able to conduct 3 sorption/desorption cycles within 10 hours during one day test in the outdoor condition and produced 1.6 kgwater/kgsorbent. A prototype of continuous AWG device was designed, fabricated, and successfully demonstrated, hinting a possible way of large-scale deployment of AWG for practical purposes.

The spraying method is developed for the fabrication of mechanically robust and self-healing superhydrophobic coatings, which comprise highly porous and rough polyelectrolyte coatings preserved with low-surface-energy healing agents. These coatings can repetitively and autonomically restore superhydrophobicity in humid environments. After depletion of healing agents, superhydrophobic coatings with dual healing agents can regain their self-healing ability by re-spraying fluoroalkylsilane.

Healable, electrically conductive films are fabricated by depositing Ag nanowires on water-enabled healable polyelectrolyte multilayers. The easily achieved healability of the polyelectrolyte multilayers is successfully imparted to the Ag nanowire layer. These films conveniently restore electrical conductivity lost as a result of damage by cuts several tens of micrometers wide when water is dropped on the cuts.

More than 600 gigawatts (GW) photovoltaic (PV) panels are currently installed worldwide, with the predicted total capacity increasing very rapidly every year. One essential issue in PV conversion is massive heat generation of PV panel under sunlight, which represents 75% to 96% of the total absorbed solar energy and thus greatly increases temperature and decreases the energy efficiency and lifetime of the PV panel. In this work, we demonstrate a new and versatile PV panel cooling strategy that employs sorption-based atmospheric water harvester (AWH) as effective cooling component. The AWH based PV cooling provides an averaged cooling power of 295 W/m 2 and lowers temperature of PV panel by at least 10 o C under 1.0 kW/m 2 solar irradiation in lab conditions. It delivers 13% to 19% increase in electricity generation of the commercial PV panels in outdoor field tests conducted in winter and summer in Saudi Arabia. The AWH based PV panel cooling strategy has little geographical constrain in its application and is promising in improving electricity productivity of existing and future PV plants, which can be directly translated into less CO2 emission or less land occupation by PV setup. As solar power is taking a central stage in the global fight against climate change, AWH based cooling represents a solid force toward sustainability.

Smart windows with high near-infrared (NIR) light shielding and controllable visible light transmittance are highly sought after for cooling energy saving in buildings. Herein we present a rationally designed spectrally selective smart window which is capable of shielding 96.2% of the NIR irradiation from 800 nm to 2500 nm and at the same time permitting acceptable visible light (78.2% before and 45.3% after its optical switching) for indoor daylighting. The smart window synergistically integrates the highly selective and effective NIR absorption based photothermal

Hygroscopic salt-hydrogel composite sorbents have attracted increasing attention for atmospheric water harvesting (AWH) applications but suffer from the salting-out effect. To this end, this work, for the first time, discovers that the salting-in effect possessed by a zwitterionic hydrogel is able to facilitate water vapor sorption by the hygroscopic salt under otherwise the same conditions. For demonstration, zwitterionic hydrogel of poly-[2-(methacryloyloxy)­ethyl]­dimethyl-(3-sulfopropyl)­ammonium hydroxide (PDMAPS) was synthesized, and the hygroscopic salt of LiCl was embedded into PDMAPS to produce the salt-hydrogel composite. LiCl salt not only endows the sorbent with high water vapor sorption capacity but also facilitates the dissociation of self-association between cationic and anionic groups of PDMAPS. This salting-in effect was evaluated and confirmed experimentally and via density functional theory (DFT) calculation. The salting-in effect renders the zwitterionic hydrogel matrix with enhanced swelling capacity, leading to the sorbent’s high AWH performance. With a photothermal component of CNT integrated into the sorbent, a fully solar energy-driven AWH process was demonstrated outdoors. This study provides important guidance to the design of hydrogel-based AWH sorbents.