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.