Solar-driven multi-field synergistic strategy for integrated freshwater production and boron harvesting

The worsening water-food-energy nexus presents a critical challenge for sustainable development. Simultaneously extracting freshwater and boron from seawater or brine with minimal energy input offers a promising yet underexplored strategy to address these interconnected issues. Herein, we propose a solar-driven multi-field synergistic strategy that rationally integrates temperature, concentration, and flowing fields to co-harvest freshwater and boron resources. For conceptual demonstration, we fabricated a (MXene-MgO)@sodium alginate (SA) composite gel (i.e., MMS) by co-doping MgO (a boron adsorbent) and MXene (a dual-functional material acting as both photothermal converter and boron adsorption aid) into an SA matrix. Under 1 sun illumination, the developed MMS demonstrated a high evaporation rate of 2.14 kg m^–2 h^–1 and a boron adsorption capacity of 225.52 mg m^–2 within 9 h. Outdoor field tests further well validated its practical viability, yielding 5.20 kg m^–2 of freshwater and recovering 122.45 mg m^–2 of boron daily. Most notably, the recovered boron could remarkably enhance agricultural productivity, increasing the seed germination rate by 13% and tripling biomass production relative to the boron-deficient control. Overall, this work establishes a revolutionary paradigm within the water-food-energy nexus, particularly relevant for resource-scarce coastal regions.