Salt-Templated Crystallization Yields Oriented Interconnected Macroporous Polymer Gels for Ultrafast and High-Capacity Atmospheric Water Harvesting.

Abstract

Sorption-based atmospheric water harvesting (SAWH) is a promising strategy for freshwater production. While salt-based composites are widely employed as SAWH sorbents, they are often constrained by limited water yield from low sorption capacity and slow sorption/desorption kinetics due to diffusion barriers. Here, a new strategy is proposed to enhance moisture transport and storage space by fabricating oriented interconnected macroporous polymer gels via salt-templated crystallization-induced confined polymerization. Benefiting from this optimized interconnected hierarchical structure and the synergistic effect between PAMPS and LiCl, the salt-templated crystallization gel (STC/TiN-gel@LiCl) exhibits a record-breaking moisture uptake of 7.19 g g^- ¹, ultrafast sorption kinetics of 1.96 g g^- ¹ h^- ¹, and rapid desorption rate of 96.8% per hour under 1.0 sun illumination. After 20 cycles under high-humidity conditions (25°C, 90% RH), the gel retains over 90.4% of its initial water uptake capacity without leakage, confirming its long-term durability. Moreover, it delivers an outstanding water production rate of 3.29 kg kg^- ¹ day^- ¹ even under low-temperature and moderate humidity conditions (14.5°C, 55.6% RH). This work pioneers an oriented interconnected macroporous architecture engineering strategy to concurrently unlock rapid transport and high-capacity storage in hygroscopic gels, establishing a new paradigm for atmospheric water harvesting.