Synergistic MOF-based composite enabling significant solar-to-water generation enhancement in climate-resilient AWH.

Abstract

Solar-driven atmospheric water harvesting (SAWH) holds significant promise for decentralized water supply. However, its widespread application is hindered by two critical limitations: underutilization of high-humidity adsorption windows during nighttime and insufficient desorption during daytime due to the high desorption temperature requirement of conventional sorbents. To overcome these challenges, this study proposes a composite sorbent strategy by synergistically combining the low enthalpy of vaporization of LiCl with the robust adsorption capacity and stability of a metal‒organic framework (MOF, specifically Ni₂Cl₂(BTDD), H₂BTDD = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin). This design leverages the complementary properties to achieve lower desorption temperatures (e.g., < 60 ^oC in device level) compared to typical MOF-based systems (usually >90 ^oC in device level), thereby significantly reducing the energy consumption for desorption. Concurrently, the composite exhibits extended adsorption duration within the high-humidity window. Field validation across diverse climatic regions demonstrates the composite's exceptional wide-range environmental stability and performance. The resulting SAWH device achieves a solar-to-water generation improvement up to 91% in a continental field test. This work presents a generalizable and effective pathway for enhancing SAWH performance through synergistic material engineering, enabling efficient water production and thermal control under varying environmental conditions.