Conductive Metal-Organic Framework Nanosheets Constructed Hierarchical Water Transport Biological Channel for High-Performance Interfacial Seawater Evaporation.

Abstract

Solar interfacial water evaporation shows great potential to address the global freshwater scarcity. Water evaporation being inherently energy intensive, Joule-heating assisted solar evaporation for addressing insufficient vapor under natural conditions is an ideal strategy. However, the simultaneous optimization of low evaporation enthalpy, high photothermal conversion, and excellent Joule-heating steam generation within a single material remain a rare achievement. Herein, inspired by the biological channel structures, a large-area film with hierarchical macro/microporous structures is elaborately designed by stacking the nanosheet of a conductive metal-organic framework (MOF), Ni₃(HITP)₂, on a paper substrate. By combining the above three features in one material, the water evaporation enthalpy reduces from 2455 J g^-1 to 1676 J g^-1, and the photothermal conversion efficiency increases from 13.75% to 96.25%. Benefiting from the synergistic photothermal and Joule-heating effects, the evaporation rate achieves 2.60 kg m^-2 h^-1 under one sun plus input electrical power of 4 W, surpassing the thermodynamic limit and marking the highest reported value in MOF-based evaporators. Moreover, Ni₃(HITP)₂-paper exhibits excellent long-term stability in simulated seawater, where no salt crystallization and evaporation rate degradation are observed. This design strategy for nanosheet films with hierarchical macro/microporous channels provides inspiration for electronics, biological devices, and energy applications.