Self-assembled hierarchically porous composite film with ultrahigh MIL-101 loading for efficient atmospheric water...

Processing metal-organic frameworks (MOF) powders into bulk materials is highly desirable to enhance their practicality in sorption-based atmospheric water harvesting (SAWH) applications. However, few studies have reported such bulk materials with both high MOF loading and particle visibility. In this study, a composite adsorbent (denoted as SA-TA@MIL-101) was successfully prepared via a simple self-assembly and Fe³⁺ ion cross-linking method. This material features high MIL-101 loading (67 wt%), a thin-layered structure (∼ 80 um), and a hierarchical pore distribution (size distribution ranging from 1 to 3 nm and from 40 to 110 nm), which not only provides abundant water adsorption sites but also significantly reduces vapor transfer resistance during both adsorption and solar-driven desorption processes. As a result, it achieves a high water uptake capacity (0.211 g g^-1 at 30% RH, 0.538 g g^-1 at 50% RH, and 0.725 g g^-1 at 70% RH) within 1 h and releases over 90% of the absorbed water in approximately 30 min under 1 sun illumination (1 kW m^-2). In outdoor tests, the composite adsorbent achieved a daily water production of approximately 2.055 g g^-1, and preliminary validation confirmed the feasibility of using the harvested water for agricultural irrigation. This study proposes a simple and effective strategy to prevent MOF aggregation during application, offering valuable insights for the design and preparation of high-performance SAWH materials.