MOF supraparticles for atmosphere water harvesting at low humidity

Developing efficient water adsorbents for atmospheric water harvesting in desert regions still remains a challenge due to the lack of useful strategies to enhance low-pressure water uptakes and adsorption–desorption kinetics. Herein we demonstrate a simple and efficient polyvinylpyrrolidone (PVP) assisted self-assembly strategy for the fabrication of core–shell MOF-801@MIL-101(Cr) (M-8010) supraparticles. The water uptake capacity of the prepared supraparticles is about 225% and 390% higher than that of pure MOF-801 and MIL-101 at 8% RH, respectively, benefiting from the synergistic effect between the preconcentration functions of shell MOF-801 and the high storage capacity of core MIL-101. Fast water capture and release kinetics of M-8010 supraparticles is also achieved. Their water collection rate is estimated to be about 0.253 Lwater/kgadsorbents per day under 10–20% RH, demonstrating that the M-8010 supraparticles are a great potential and stable adsorbent for water harvesting under extremely arid environments. This work may pave a new way to design MOF@MOF supraparticles for high-performance water harvesters in desert areas.