Fe3+-coordinated Dual-crosslinked Conjugated Polymer Hydrogels with Ultrahigh Evaporation Rate for Efficient Desalination and Sustainable Agriculture

The development of solar-driven interfacial evaporation technology is pivotal for addressing global water scarcity. However, it is hindered by the difficulty in synergizing high photothermal conversion with low water evaporation enthalpy into a single material. Herein, we propose an iron-aldehyde-cooperative dynamic covalent anchoring strategy, successfully constructing a covalently locked, hydroxymethyl-functionalized PEDOT-PVA integrated dual-network hydrogel (MEPH). This strategy employs Fe 3+ to achieve the one-step in situ oxidative polymerization of hydroxymethyl EDOT while concurrently forming a physical hybrid network with PVA, which is subsequently reinforced by covalent cross-linking using glutaraldehyde. This design endows the MEPH with exceptional broadband light absorption (>99%), efficient water transport, and regulated water state within the hydrogel matrix, leading to a reduced evaporation enthalpy of 732 J·g −1 . The resulting evaporator achieves an ultrahigh evaporation rate of 4.95 kg·m −2 ·h −1 under 1-sun illumination, corresponding to an energy conversion efficiency exceeding 95%, while maintaining stable, salt-resistant operation in high-salinity environments. Outdoor experiments validate its outstanding practicality for seawater and wastewater purification, with the produced freshwater significantly promoting plant growth, highlighting its great potential in sustainable agricultural water cycles. This iron-aldehyde-cooperative dynamic covalent anchoring strategy provides an innovative design paradigm for a new generation of high-performance and robust solar evaporators.