A porous calcium alginate aerogel of surface hydroxylated MOF-801 for enhancing solar-driven atmospheric water harvesting

Sorption-based atmospheric water harvesting (SAWH) technology can adsorb water vapor from the ambient air to produce clean water, which is a promising strategy for alleviating the shortage of freshwater resources. Herein, this study reported a hydroxylated MOF-801 (M1OH) coupled with polydopamine (PDA) and calcium alginate (CA) to form a PDA/M1OH/CA (PDA/M1OHC) aerogel for use in highly efficient solar-driven SAWH. The interaction between the network hydrophilic groups of PDA/M1OHC and adsorbed water produced more free water and weakly bound water, significantly reducing the evaporation enthalpy to 785.1 J g −1 . Thanks to the hydrogen bond adsorption of water molecules by Zr-OH groups, the developed PDA/M1OHC achieved a high-water absorption rate of 1.390 g g −1 at 60 % RH. Therefore, based on the high-water absorption performance and low evaporation enthalpy of PDA/M1OHC, in actual outdoor SAWH, 1.647 kg kg −1 of clean water that satisfies World Health Organization drinking water standards could be collected in a single day in actual outdoor SAWH under outdoor conditions of 30.18 °C and 63.72 % RH. This study developed PDA/M1OHC SAWH material with high water absorption performance and low evaporation enthalpy, which is expected to become a sustainable strategy for collecting fresh water from the atmosphere. • Surface-hydroxylated MOF-801 exhibited a higher content of Zr-OH groups. • The Zr-OH rich M1OH improved the water sorption capability of PDA/M1OHC. • PDA/M1OHC had high water absorption capacity over a wide range of RH. • Hydroxylation reduced the evaporation enthalpy during desorption of PDA/M1OHC. • The PDA/M1OHC aerogel performed excellently in actual outdoor SAWH.