Immobilization of Lewis Basic Nitrogen Sites into a Chemically Stable Metal–Organic Framework for Benchmark Water‐Sorption‐Driven Heat Allocations

Abstract

Developing efficient and stable water adsorbents for adsorption-driven heat transfer technology still remains a challenge due to the lack of efficient strategies to enhance low-pressure water uptakes. The authors herein demonstrate that the immobilization of Lewis basic nitrogen sites into metal-organic frameworks (MOFs) can improve water uptake and target benchmark coefficient of performances (COPs) for cooling and heating. They present the water sorption properties of a chemically stable MOF (termed as Zr-adip), designed by incorporating hydrophilic nitrogen sites into the adsorbent MIP-200. Zr-adip exhibits S-shaped sorption isotherms with an extremely high water uptake of 0.43 g g −1 at 303 K and P/P 0 = 0.25, higher than MIP-200 (0.39 g g −1 ), KMF-1 (0.39 g g −1 ) and MOF-303 (0.38 g g −1 ). Theoretical calculations reveal that the incorporated N sites can serve as secondary adsorption sites to moderately interact with water, providing more binding sites to strengthen the water binding affinity. Zr-adip achieves exceptionally high COPs of 0.79 (cooling) and 1.75 (heating) with a low driving temperature of 70 °C, outperforming MIP-200 (0.78 and 1.53) and KMF-1 (0.75 and 1.74). Combined with its ultrahigh stability, excellent cycling performance, and easy regeneration, Zr-adip represents one of the best water adsorbents for adsorption-driven cooling and heating.

Systematic evaluation of water adsorption in isoreticular UiO-type metal–organic frameworks

“…12,13 In the last decade, a number of MOFs have been exploited as outstanding adsorbents for water-sorption applications by the powerful strategies of fine-tuning pore size and pore functionalization. 6,14 For example, some aluminum- and zirconium-based MOFs (Al-MOFs and Zr-MOFs) with fine-tuned pore size or pore hydrophilia have been realized to show some of the highest low-pressure water capture capacities, such as MIL-160, 15 CAU-10-H, 16 CAU-23, 17 MOF-303, 7 KMF-1, 18 and MIP-200. 19 The incorporation of functional groups ( e.g.…”

MOF supraparticles for atmosphere water harvesting at low humidity

“…A comparative chart of the water uptake performance of the M-8010 supraparticles with other reported water adsorbents 14,17,[41][42][43][44][45][46][47][48][49] including Zr-based MOFs, Al-based MOFs, Ni 2 -Cl 2 BBTA, MOF-74, MIL-101 and Basolite A300 is shown in Fig. 5a.…”

“…14,15 In this regard, metal-organic frameworks (MOFs), an emerging class of crystalline porous materials, are considered to be the next generation of water harvesting systems owing to their ultrahigh porosity, excellent cycling performance and easy regeneration. 16,17 For water harvesting in desert areas, water capture is desirable at low relative pressures (P/P 0 < 0.2). However, low daytime humidity ($10% RH) would prevent water adsorption, as the RH is lower than the adsorption step of most MOFs.…”

Hygroscopic and Photothermal All-Polymer Foams for Efficient Atmospheric Water Harvesting, Passive Humidity Management, and Protective Packaging

“…(ii) One of the polymers’ main advantages is their processability, customizability, and adjustability compared to inorganic desiccants. However, shape-controlled and large-scale fabrication of polymer-based desiccants (i.e., natural and synthetic polyelectrolytes) remains elusive. − Hybrid and system-level design of enlarged hygroscopic areas, efficient water diffusion pathways, high water retention, and rapid water release in 3D hybrid desiccants are still beyond reach. , (iii) Aside from moisture harvesting and clean water production, the integration of polymer-based desiccants into emerging energywise technologies (i.e., humidity control, passive cooling, solar-powered irrigation, and energy regeneration) has attracted growing attention. ,,− We suggest that the excellent mechanical properties of processable polymers would provide a new function for polymer-based desiccants, which can be used as versatile cushioning materials in the protective packaging of humidity-sensitive products (i.e., fruits and electronics). To the best of our knowledge, such a proof of concept has not been reported yet.…”