Flexible bimetallic MOF-based evaporator with synergistic water activation for highly efficient solar interfacial evaporation

Solar interfacial evaporation (SIE) is regarded as a sustainable strategy for addressing global freshwater scarcity. However, further breakthroughs in evaporation efficiency are fundamentally restricted by the thermodynamic bottleneck of the high latent heat of water vaporization. Although metal-organic frameworks (MOFs) have shown promise in modulating the water state, the fixed electronic environment of conventional monometallic MOFs struggles to achieve a delicate balance between water adsorption and desorption, thereby limiting the maximization of continuous vapor generation. Herein, we construct a highly efficient, flexible, and self-cleaning FCMC evaporator by growing Fe/Cu bimetallic MOFs on a carbon cloth (CC) substrate. Benefiting from the synergistic charge rearrangement between the bimetallic Fe/Cu nodes, the composite optimizes the binding energy with water molecules and effectively disrupts the hydrogen-bond network. This significantly increases the proportion of intermediate water, reducing the evaporation enthalpy (DSC-derived) of confined water to 1250.8 J g −1 . Concurrently, the unique fully hydrophilic channels of the FCMC exhibit an ultrafast wetting behavior within milliseconds (20 ms). This induces a robust kinetic pumping effect that ensures a sufficient water supply during high-flux evaporation. Driven by this “dual-engine” mechanism—thermodynamic water activation and kinetic transport acceleration—the FCMC achieves an outstanding evaporation rate of 2.31 kg m −2 h −1 under 1-sun illumination. Furthermore, the device demonstrates remarkable salt-reflux capabilities and efficient rejection of organic dyes. This work integrating bimetallic electronic regulation with a fully hydrophilic interfacial design, provides a new pathway for developing next-generation, high-performance, and salt-resistant devices for solar desalination and wastewater purification.