Atmospheric Water Harvesting by Large-Scale Radiative Cooling Cellulose-Based Fabric

Abstract

Atmospheric water harvesting (AWH) has received tremendous interest because of population growth, limited freshwater resources, and water pollution. However, key challenges remain in developing efficient, flexible, and lightweight AWH materials with scalability. Here, we demonstrated a radiative cooling fabric for AWH via its hierarchically structured cellulose network and hybrid sorption–dewing mechanisms. With 8.3% solar absorption and ∼0.9 infrared (IR) emissivity, the material can drop up to 7.5 °C below ambient temperature without energy consumption via radiative cooling. Water adsorption onto the hydrophilic functional groups of cellulose is dominated by sorption at low relative humidity (RH) and dewing at high RH. The cellulose network provides desirable mechanical properties with entangled high-aspect-ratio fibers over tens of adsorption–extraction cycles. In the field test, the cellulose sample exhibited water uptake of 1.29 kg/kg at 80% RH during the night. The profusion of radiative cooling fabric features desirable cost effectiveness and allows fast deployment into large-scale AWH applications.

Sorbents for Atmospheric Water Harvesting: From Design Principles to Applications

“…Second, it is important to explore materials that can release water at lower temperatures, such as materials with reduced evaporation enthalpy. Third, as mentioned previously, the development of the release process caused by other stimuli, such as mechanical release, [102] is an alternative for practical applications since no thermal energy is involved in the process, which can simplify the device design and system optimization. Besides, the standardized testing parameters are imperative to evaluate the AWH performances of the materials comprehensively.…”

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

“…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). − …”

A Zero‐Energy, Zero‐Emission Air Conditioning Fabric

“…developed an atmosphere water harvesting fabric by using cellulose fabric's multiscale cellulose network and adsorption–condensation mechanism. [ 27 ] The obtained fabric exhibits 8.3% solar absorption and ≈0.9 IR emissivity that enable cooling up to 7.5 °C below ambient temperature with energy‐free radiative cooling. Li et al.…”