Solar-powered mixed-linker metal–organic frameworks for water harvesting from arid air

Metal–organic frameworks (MOFs) are a class of promising nanomaterials for atmospheric water harvesting (AWH), especially in arid remote areas. However, several challenges are still faced for practical applications because of the dissatisfied water adsorption/desorption properties in terms of the capability, kinetics, and stability. Herein, we report the facile synthesis of a nano-sized octahedral nitrogen-modified MOF-801 that exhibits superior solar-powered AWH performance using a custom-made device, with a state-of-the-art water harvesting ability up to $4.64L_{H_{2}O}{{\mathrm{kg}}_{\text{MOFs}}}^{-1}$ from air upon 12-h test under a relative humidity (RH) of 30% and simulated sunlight irradiation. The nitrogen-modified MOF-801 with rapid sorption–desorption kinetics, uptakes $0.29g_{H_{2}O}{g_{\text{MOFs}}}^{-1}$ of water at 30% RH within 30 min and releases 90% of the captured water within 10 min under 1-sun illumination. The success relies on N-doping-induced mixed-linkers in the form of 2,3-diaminobutanedioic acid and fumaric acid in the unique pore structures of the MOFs for rapid and high-capacity water capture. The N-doped MOF-801 with water uptake capacity, fast adsorption kinetics, and cycle stability sheds light on the practical use of MOFs for effective solar-powered water harvesting from droughty air.