Porous Materials for Atmospheric Water Harvesting

Abstract

Atmospheric Water Harvesting (AWH) using porous adsorbents is emerging as a promising solution to combat water shortage. Thus, a clearer understanding of the developing trends and optimization strategies of different porous adsorbents can be extremely helpful. Therefore, in this concept, the different types of porous adsorbents and AWH devices are briefly introduced with a focus on the factors that influence the static and kinetic properties of porous adsorbents and their respective optimization strategies. In addition, the fast transport characteristics of water molecules in micropores are studied from the perspective of superfluidity as part of the analysis of the kinetic properties of porous adsorbents. Finally, the future development of porous materials for AWH and the accompanying challenges are summarized.

Keywords: atmospheric water harvesting; kinetic process; porous materials; superfluidity; water adsorption.

Figure 1

AWH can be affected through four aspects: Diversified adsorbents; static performance; kinetic performance; devices.

Figure 2

a) The pore size and water adsorption capacity of different nanopore carbon samples. Reproduced with permission from Ref. [30]. Copyright 2022 Springer Nature. b) Scheme of hollow MIL‐101(Cr) and its water adsorption isotherm at 298 K. Reproduced with permission from Ref. [31]. Copyright 2022 American Chemical Society.

Figure 3

a) The water sorption analyses on the multivariate MOF series at 298 K. Reproduced with permission from Ref. [33]. Copyright 2021 The American Association for the Advancement of Science. b) The water vapor adsorption isotherm of AB‐COF and COF‐480‐hydrazide under 298 K. Reproduced with permission from Ref. [17c]. Copyright 2022, American Chemical Society. c) Water adsorption and release processes of SHPFs. Reproduced with permission from Ref. [12d]. Copyright 2022 Springer Nature.

Figure 4

a) The structure and water vapor adsorption isotherm at 298 K of DUT‐175 and DUT‐176. Reproduced with permission from Ref. [28a]. Copyright 2021 American Chemical Society. b) The structure and water vapor adsorption isotherm at 298 K of HFPTP‐PDA‐COF (red) and HFPTP‐BPDA‐COF (black). Reproduced with permission from Ref. [34]. Copyright 2021 Springer Nature.

Figure 5

a) Water vapor transport pathways of NBHA in solar‐powered regeneration. Reproduced with permission from Ref. [12c]. Copyright 2021 Elsevier. b) Inter‐ and intra‐crystalline diffusion of water vapor in the vertically aligned nanocomposite sorbent, and schematic depiction of water vapor transport pathways in the vertically aligned macropores. Reproduced with permission from Ref. [12a]. Copyright 2021 Royal Society of Chemistry.

Figure 6

a) Schematic depiction of the preparation process for photothermal TUN/SA adsorbent and its photothermal conversion performance. Reproduced with permission from Ref. [26a]. Copyright 2021 American Chemical Society. b) Structure of photothermal organogel (POG) and its moisture sorption and water releasing diagram. Reproduced with permission from Ref. [10b]. Copyright 2020 John Wiley and Sons. c) Schematic illustration of express mode and normal mode for water release powered by solar energy. Reproduced with permission from Ref. [13a]. Copyright 2019 John Wiley and Sons.

Figure 7

a) Energy barrier for the diffusion processes of H₂O in a slit‐shaped carbon pore model with various geometric and chemical properties. Reproduced with permission from Ref. [30]. Copyright 2022 Springer Nature. b) Schematic of water adsorption on CPOS‐6 with a dual hydrogen bond system under different humidity conditions. Reproduced with permission from Ref. [19]. Copyright 2022 John Wiley and Sons.

Figure 8

a) Water release process of PCA‐MOF cone array. Reproduced with permission from Ref. [14]. Copyright 2020 The American Association for the Advancement of Science. b) Schematic depiction of the AWH process of GO‐SSNF. Reproduced with permission from Ref. [41]. Copyright 2021 Elsevier.

Figure 9

a) Schematic depiction of the water harvester consisting of a water sorption unit and a case. Reproduced with permission from Ref. [24b]. Copyright 2018 The American Association for the Advancement of Science. b) Photograph of the water harvester with labeled parts. Close‐up views of the MOF exchanger and the water collected under continuous operation. Reproduced with permission from Ref. [36]. Copyright 2019 American Chemical Society.

Figure 10

a) Photograph of the water harvester consisting of a honeycomb structure adsorbent bed. Reproduced with permission from Ref. [42a]. Copyright 2022 Elsevier. b) Design scheme of the water collection device. Reproduced with permission from Ref. [12d]. Copyright 2022 Springer Nature. c) The dual‐stage AWH concept. Reproduced with permission from Ref. [43]. Copyright 2021 Elsevier.