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 (Al-Fu@Cu@CuxS) for rapid AWH, with CuxS layer, Cu layer and Al-fumarate MOF coating from top to bottom. In Al-Fu@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 ℃ 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.