Research ArticleAPPLIED SCIENCES AND ENGINEERING

Autonomous atmospheric water seeping MOF matrix

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Science Advances  16 Oct 2020:
Vol. 6, no. 42, eabc8605
DOI: 10.1126/sciadv.abc8605
  • Fig. 1 Design of the autonomous airborne water supplier.

    Schematic illustration shows the hydro-active sites on polymer chains that capture atmospheric moisture. Under steric pressure and restricted expansion, the polymer-MOF hybrid pore enables self-seepage for direct water harvesting from ambient.

  • Fig. 2 Fabrication and characterization of the PC-MOF.

    (A) Units and crystal structure of MIL-101(Cr), schematic cross-linking process of the NIPAM monomer by the mBAm cross-linker, and schematic preparation of the P-MOF mixed-matrix hydrogel. (B) SEM image of the freeze-dried P-MOF mixed-matrix hydrogel. (C) Salinization process of the P-MOF mixed-matrix hydrogel to the PC-MOF mixed-matrix hydrogel. (D) XRD patterns of the MIL-101(Cr), PNIPAM, CaCl2, and PC-MOF. (E) High-resolution C1s XPS spectrum of the PC-MOF. a.u., arbitrary units.

  • Fig. 3 Atmospheric water uptake and direct release performance of the PC-MOF.

    (A) Schematic illustration of the water harvesting processes; ① direct water release and ② water retention. (B) Continuous water uptake performance of the PC-MOF for 72 hours at 90% RH. (C) Left: Water uptake mechanism, and performance of the PC-MOF under various RH environments after 24 hours. Right: Measured concentrations of Ca2+ and Cr3+ ions in the water collected after 12 and 24 hours of continuous sorption and direct release process at 90% RH. (D) Water uptake rate of the PC-MOF at RHs of 30, 60, and 90%. (E) FTIR spectra of the PNIPAM, PC, P-MOF, and PC-MOF. (F) Raman spectra of the PNIPAM, PC, P-MOF, and PC-MOF after 1-hour adsorption at 90% RH. All moisture sorption experiments were conducted at 25°C.

  • Fig. 4 Optional thermal activation of the PC-MOF for complete water desorption.

    (A) Optical microscope images demonstrating the temperature-dependent dynamic phase separation behavior of the PC-MOF containing detained water. (B) The thickness of water layer on the PC-MOF surface at various temperatures as determined by the AFM force curve measurements. (C) Arrhenius plot representing the evaporation rate of detained water in PC-MOF as a function of temperature. (D) Schematic illustration of the water evaporation through photothermal effect. (E) The ambient temperature and humidity as functions of time during water harvesting. (F) Photograph of the proof-of-concept prototype for atmospheric water harvesting. (G) Water uptake performance of the PC-MOF; blue and pink portions represent direct water release and water retention, respectively. Photo credit: Connor Kangnuo Peh, National University of Singapore.

  • Fig. 5 Photothermal engineering and structural design.

    (A) Schematic illustration and digital image of the PCA-MOF cone array. (B) TEM image of the Au@MIL-101(Cr) nanoparticles. The enlarged image shows the HRTEM of Au nanoparticles, and the histogram shows the corresponding size distribution. (C) Reflectance spectra of the PC, PC-MOF, and PCA-MOF. (D) Temperature changes of the PC, PC-MOF, and PCA-MOF over time under 1 sun solar irradiation. (E) Daily on-off cycle: Daily water uptake performance of the PCA-MOF cone array using solar-assisted regeneration. Continuous: Total amount of water uptake after 12 hours (11:00 p.m. to 11:00 a.m.) and 24 hours (11:00 p.m. to 11:00 p.m., next day) without solar-assisted regeneration. (F) Water sorption (2 hours)–release (1 hour) cycles for the PCA-MOF. Photo credit: Gamze Yilmaz, National University of Singapore.

Supplementary Materials

  • Supplementary Materials

    Autonomous atmospheric water seeping MOF matrix

    G. Yilmaz, F. L. Meng, W. Lu, J. Abed, C. K. N. Peh, M. Gao, E. H. Sargent, G. W. Ho

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