Ferrocene Dicarboxylic Acid Ligand-Exchanged Hollow MIL-101(Cr) Nanospheres for Solar-Driven Atmospheric Water Harvesting

Abstract

Developing efficient water adsorbents for solardriven atmospheric water harvesting (AWH) still remains a challenge due to the poor photothermal heating ability and slow sorption kinetics of most adsorbents. Postsynthetic ligand exchange (LE) provides an alternative strategy to prepare metal−organic framework (MOF) materials with varied structures and functions. In this work, multifunctional hollow MIL-101(Cr) with ferrocene dicarboxylic acid (Fc(COOH) 2 ) ligand exchanged (HMF) nanospheres are prepared and utilized for efficient AWH. The resulted HMF nanospheres present great visible light absorption (>80%) and photothermal conversion ability (61.6%) due to the introduced Fc(COOH) 2 ligand. The water adsorption and desorption rates of the HMF nanosorbent are 2.3 times and 4.5 times that of MIL-101(Cr). The fast water capture and solar-driven release kinetics of HMF nanosorbents indicate its great potential for actual water harvesting. The outdoor water collection experiment demonstrates that the areal water harvesting capacity of the HMF nanosorbent is 1720 g m −2 per cycle with packed thickness of 8 mm. HMF nanosorbents also demonstrate good antibacterial activity (91.4%), which is beneficial to the collection of healthy and safe water. This work provides a facile and practical method to design multifunctional MOFs from the molecular level by LE and to achieve solar-driven AWH and other fields.

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

“…Owing to solar-powered water evaporation, water contents of 3D foam-3 gradually declined under solar irradiation over time (Figure d). The water desorption kinetics can be expressed using eq , , R normald = m s − m m 0 t where R d (h –1 ) is the water desorption rate, m s (g) is the weight of water-saturated 3D foam-3, m (g) is the weight of dehydrated 3D foam-3 at time t (h), and m 0 (g) is the weight of dry 3D foam-3. Low sunlight (0.4 sun) enabled wet 3D foam-3 to release 39.2% of the adsorbed water in 5 h, leading to a R d of 0.18 h –1 .…”

“…Although some powder and liquid desiccants (i.e., hygroscopic salts, silica gel, zeolite, and glycerin) have been used for conventional sorption-based dehumidification, there are significant challenges in developing bulk desiccants with tailorable structures, stable water adsorption/desorption, and low energy input for regeneration. − The incorporation of organic/inorganic hybrid desiccants within porous three-dimensional (3D) scaffolds is of particular interest, enabling the development of hybrid desiccants with multidimensional shapes (i.e., fabrics, gels, membranes, aerogels, hydrogels, and foams). − Emerging desiccants based on metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have shown rapid water vapor adsorption and desorption. − It is noted that 3D hybrid desiccants can release water and become regenerated via low-grade thermal energy intake (i.e., waste heat and solar energy) with the help of photothermal or radiative cooling materials, minimizing the carbon footprints of air conditioning. − The reversible water uptake/release and good long-term stability provide a potential avenue for using 3D hybrid desiccants as indoor humidity regulators compared to conventional humidifiers (i.e., based on evaporation and steam) and dehumidifiers (i.e., based on air conditioning and refrigeration). − …”

Marine biomass-derived, hygroscopic and temperature-responsive hydrogel beads for atmospheric water harvesting and solar-powered irrigation

“…6d). Water desorption kinetics of the cl -SP beads can be expressed using eqn (3) and (4), 44 where P d (%) is the percentage of desorbed water mass to initial absorbed water mass. R d (h −1 ) is the water desorption rate, m s (g) is the weight of the water-saturated cl -SP beads, m (g) is the weight of dehydrated cl -SP beads at time t (h) and m 0 (g) is the weight of dry cl -SP beads.…”

“…33,34 So far, the efforts to seek high-performing hygroscopic materials with rapid water vapor sorption, high water vapor uptake, low regeneration temperature and sustainable energy input are rising. [35][36][37][38][39][40][41][42][43][44][45] Incorporation of emerging desiccants (i.e., hygroscopic salts, metal-organic complex, metal-organic frameworks and covalent organic frameworks) within porous matrices (i.e., aerogels, hydrogels, lms, fabrics and sponges) is of particular interest. Although atmospheric water is considered as a promising solution for the growing scarcity in agriculture, few sorption-based AWGs have been developed for the specic use in solar-powered irrigation.…”

“…33,34 So far, the efforts to seek high-performing hygroscopic materials with rapid water vapor sorption, high water vapor uptake, low regeneration temperature and sustainable energy input are rising. 35–45 Incorporation of emerging desiccants ( i.e. , hygroscopic salts, metal–organic complex, metal–organic frameworks and covalent organic frameworks) within porous matrices ( i.e.…”