Mechanically Robust Copper Foam-Integrated Zwitterionic Cellulose Nanofiber Aerogels with Enhanced Heat and Mass Transport for Efficient Atmospheric Water Harvesting

Addressing global water scarcity necessitates advances in sorption-based atmospheric water harvesting (AWH). While industrially favorable monolithic hygroscopic aerogels show great promise as AWH sorbents, their widespread adoption is limited by poor air permeability, low thermal conductivity, and insufficient mechanical robustness. Here, a facile and robust copper foam (CF)-mediated surface-initiated (SI)-Cu0ATRP method is presented to in-situ graft dense zwitterionic polymer brushes onto cellulose nanofiber (CNF) networks without oxygen exclusion, leading to the development of novel CF-integrated hygroscopic CNF aerogels (CHPCAs). The integrated CF not only enhances mechanical stability and thermal conductivity but also preserves the inherent porous architecture of CNFs, ensuring excellent air permeability. These synergistic properties endow CHPCAs with exceptional moisture adsorption kinetics and capacity, alongside efficient water desorption. A CHPCA-based AWH prototype demonstrated significant water productivity under various air conditions, achieving rates of 6.65 LH2O·kg-1CHPCA per day with an energy consumption of 3.03 kWh L-1H2O in outdoor conditions (13.1-20.3 °C, 25.4-81.6% RH). This work represents the first demonstration of SI-Cu0ATRP for fabricating 3D structured aerogels, presenting a scalable, robust, and high-performance monolithic AWH sorbent with significant potential for practical water harvesting applications.