Solar-driven MXene-based DES nanofluid coupled with high-reflectivity PVDF/PMMA film for efficient atmospheric water harvesting

Abstract

Solar-driven atmospheric water harvesting is an innovative technology that utilizes solar energy to convert light into heat, promoting the condensation of water vapor from the air and enabling efficient water collection. The overall light absorption capacity of the system and the energy conversion efficiency of photothermal nanofluids are critical factors limiting the efficiency of water harvesting. In this study, a deep eutectic solvent (DES) nanofluid was developed using choline chloride (ChCl) and urea, with MXene introduced to enhance the photothermal conversion capability. Under solar irradiation of 1000 W/m², the MXene nanofluid with a concentration of 0.05 wt% achieved a photothermal conversion efficiency of 94.3 %. A high-reflectivity polyvinylidene fluoride (PVDF)/polymethyl methacrylate (PMMA) film was fabricated via electrospinning and combined with the DES-based nanofluid, increasing the overall light absorption through an extended optical path. This coupled system demonstrated a 49 % increase in water evaporation rate compared to the original nanofluid, reaching 0.91 kg/m²·h. The system exhibited stable evaporation performance in outdoor environments, with an average evaporation rate of 0.64 kg/m²·h. This research provides new insights and technological support for efficient solar energy collection and water resource utilization, offering significant potential for practical applications.