Oriented lamellar PEG-based nanocomposite with adjustable thermal transfer efficiency for efficient atmospheric water harvesting

Abstract

Water loss rate is crucial in evaluating the efficiency of atmospheric water harvesting (AWH) materials. However, most moisture-absorbing salts and gels have fixed heat transfer rates, limiting the development of high-performance AWH materials. Herein, an anisotropic PEG/CS/MF nanocomposite (APCM) with adjustable thermal transfer efficiency is presented. APCM was synthesized using polyethylene glycol (PEG), melamine foam (MF), and chitosan (CS) solution through a freeze orientation method. The resulting material exhibits a stable oriented laminated structure formed by hydrogen bonding between PEG, CS, and MF. This unique structure imparts excellent mechanical properties. APCM’s large lamellar gaps and pore diameters enable rapid absorption of atmospheric water molecules at low temperatures without leakage (61.79 kg m⁻³). The compressible nature of APCM allows for efficient heat transfer at high temperatures, and the release of 80% of absorbed water within 15 min. In a proof-of-concept demonstration using a custom-built AWH device, each cubic meter of APCM achieved three AWH cycles within 24 h, producing over 185 kg of water. Therefore, this innovative design offers a promising solution for enhancing the efficiency of AWH, potentially addressing water scarcity issues in various regions.