Solar-Mechano Symbiosis Dual-Mode Janus Bioaerogel for Context-Adaptive Atmospheric Water Harvesting Beyond Solar Reliance.

Abstract

Solar-driven sorption-based atmospheric water harvesting (SS-AWH) offers promise for addressing global freshwater scarcity. However, the SS-AWH heavily relies on favorable and sustained solar irradiation; yet real-world solar irradiation exhibits significant spatiotemporal fluctuations, limiting its sustainable application, as non/low-light conditions sharply reduce water productivity. This constraint is fundamentally due to the singleness of the water release pathway via photothermal desorption. Here, a novel dual-mode bio-based Janus aerogel (DBJA) is presented, enabling efficient, all-weather, multi-scenario atmospheric water harvesting via selectively solar-driven and compression-activated water release. The Janus structure optimizes mass/heat transfer between hygroscopic and photothermal domains, achieving the most balanced adsorption-desorption kinetics and compression-recovery strength for solar-mechano symbiosis. Under favorable sunlight, DBJA demonstrates a competitive water release efficiency of 1.32 g g^-1 day^-1 outdoors. Crucially, without solar irradiation, DBJA achieves a total water productivity of 12.80 g g^-1 over 5-cycle adsorption-compression with 98% volume recovery and is stable within 50 cycles. Enhanced physical inlay and multiple chemical interactions ensure limited leakage of Li⁺ ions during compression, and the collected water easily conforms to the World Health Organization (WHO) drinking water standards. This work provides a flexible approach for sustainable atmospheric water harvesting beyond solar reliance through multi-mode synergy and gradient architecture.