Sandwich-like adsorbent based on Al-fumarate MOF coating on Cu@CuxS sheet for rapid solar-driven atmospheric water harvesting

Atmospheric water harvesting (AWH) technology using MOFs as an adsorbing medium has been considered a favorable approach to alleviate water scarcity, while its practical implementation is hindered due to the low mass and heat transfer efficiency of MOFs. To solve it, we presented a solar-driven sandwich-like adsorbent (AlFu@Cu@CuxS) for rapid AWH, with CuxS layer, Cu layer and Al-fumarate MOF coating from top to bottom. In AlFu@Cu@CuxS, Al-Fu coating and CuxS layer respectively function as a water vapor cage and solar energy catcher, for water vapor absorption-desorption and photothermal conversion, and Cu among them with high thermal conductivity can quickly transfer heat to achieve rapid water generation. The experimental results showed that the resultant Al-Fu@Cu@CuxS could reach a saturated water uptake of 0.223 g/g due to a high specific surface area (1033.19 m2/g) of Al-Fu skeleton. With the assistance of CuxS, Al-Fu@Cu@CuxS could heat to 70.4 degrees C under 1 sun illumination and achieve 93.3 % water desorption within 50 min, and its photothermal conversion efficiency was as high as 95.2 %. Furthermore, in a matched AWH device, the collection water capacity of Al-Fu@Cu@CuxS was 2.14 g/cycle, much higher than that of powdered Al-Fu of 0.69 g/cycle, revealing its application potential in AWH.