A fluidic photothermal structure is demonstrated for completely salt-rejecting solar water extraction and simultaneous brine-drenching induced energy generation.

The earth's atmosphere houses an enormous amount of water, which could be effectively exploited for a plethora of applications. While the development of materials for harnessing this abundant resource has gained impetus in recent years, limited efforts have been devoted to in‐depth research on their agricultural applications. Herein, a novel copper(II)–ethanolamine complex (Cu‐complex), which has a maximum water uptake of up to 300% and a water production rate of 2.24 g g−1 h−1 under natural sunlight, is reported. As a proof‐of‐concept application, using this material, a fully automated and self‐sustainable solar‐powered SmartFarm device is developed. The Cu‐complex harvests atmospheric water during the night, stores the adsorbed water within, and efficiently releases the adsorbed water during the day when the device is exposed to sunlight. The water harvesting and irrigation process can be fine‐tuned to suit different types of plants and local climates for an optimal cultivation. With the SmartFarm in operation, the demand for freshwater for irrigation could be greatly reduced and urban farming techniques such as large‐scale rooftop farming could be promoted with a view of alleviating both water and food scarcity in the near future.

The interactions between moisture and materials give rise to the possibility of moisture‐driven energy generation (MEG). Current MEG materials and devices only establish this interaction during water sorption in specific configurations, and conversion is eventually ceased by saturated water uptake. This paper reports an asymmetric hygroscopic structure (AHS) that simultaneously achieves energy harvesting and storage from moisture absorption. The AHS is constructed by the asymmetric deposition of a hygroscopic ionic hydrogel over a layer of functionalized carbon. Water absorbed from the air creates wet‐dry asymmetry across the AHS and hence an in‐plane electric field. The asymmetry can be perpetually maintained even after saturated water absorption. The absorbed water triggers the spontaneous development of an electrical double layer (EDL) over the carbon surface, which is termed a hygro‐ionic process, accounting for the capacitive properties of the AHS. A peak power density of 70 µW cm‐3 was realized after geometry optimization. The AHS shows the ability to be recharged either by itself owing to a self‐regeneration effect or via external electrical means, which allows it to serve as an energy storage device. In addition to insights into moisture‐material interaction, AHSs further shows potential for electronics powering in assembled devices.

The salt fouling issue, which has become the major bottleneck hindering a sustainable solar desalination process in practice. Herein, a fluidic photothermal structure that is able to completely prevent salt formation for durable steam generation while achieving electricity generation during the one-way fluid transportation is reported. By continuously navigating the one-way saline fluid through solar absorber, salt rejection can be completely guaranteed during intense steam generation. The proposed strategy was demonstrated by a polyaniline (PANi)/cellulose bilayer and realized ultrahigh solar efficiency (92%) under 1 Sun illumination. We further show that electricity is synchronously generated via asymmetric deposition of functional carbon materials on capillary wicks, and voltage >0.2 V is readily derived with good scalability. This one-way fluidic structure exhibits favorable universality to nearly all the other planar solar absorbers and multistage solar stills, which would be of great practical significance to longterm solar desalination in the future.

High levels of humidity can induce thermal discomfort and consequent health disorders. However, proper utilization of this astounding resource as a freshwater source can aid in alleviating water scarcity. Herein, a low‐energy and highly efficient humidity control system is reported comprising of an in‐house developed desiccant dehumidifier and hygrometer (sensor), with an autonomous operation capability that can realize simultaneous dehumidification and freshwater production. The high efficiency and energy saving mainly come from the deployed super hygroscopic complex (SHC), which exhibits high water uptake (4.64 g g−1) and facile regeneration. Machine‐learning‐assisted in‐house developed low cost and high precision hygrometers enable the autonomous operation of the humidity management system. The dehumidifier can reduce the relative humidity (RH) of a confined room from 75% to 60% in 15 minutes with energy consumption of 0.05 kWh, saving more than 60% of energy compared with the commercial desiccant dehumidifiers, and harvest 10 L of atmospheric water in 24 h. Moreover, the reduction in RH from 80% to 60% at 32 °C results in the reduction of apparent temperature by about 7 °C, thus effectively improving the thermal comfort of the inhabitants.

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