Robust Hierarchically Porous Hydrogel Solar Evaporators Based on Metal‐Phenolic Networks‐Coated Carbon Nanotubes

Abstract Solar‐driven interfacial evaporation (SIE) emerge as a promising technology to mitigate the worldwide freshwater shortage and energy crisis. Carbon nanotubes (CNTs) are widely used for the construction of hydrogel evaporators. Nevertheless, their evaporation performance is still restricted by their poor dispersibility and strong hydrophilicity. Even worse, the agglomeration of CNTs will diminish the formation of porous structures within the hydrogels and weaken the water transportation, finally resulting in decreased evaporation efficiency. To address those issues, CNTs with improved dispersibility and hydrophilicity are successfully achieved via metal‐phenolic coordination chemistry‐based interfacial engineering. The resulting metal‐phenolic networks (MPN)‐coated CNTs are further incorporated into a poly(vinyl alcohol) hydrogel, to synergistically realize superior photothermal performance and water molecule activation. In this way, a robust solar evaporator with hierarchical pores is fabricated for efficient evaporation and mass transportation, which achieves a rate of 2.9 kg m ⁻² h ⁻¹ under 1 sun illumination while maintaining stable operation in long‐term and high‐salt environments. Actual outdoor experiments and catalytic gel formation in acrylamide hydrogels further confirm the robustness of these MPN‐coated CNT‐based devices for SIE. It is believed that this study paves a new avenue toward the development of carbon‐based hierarchically porous hydrogel evaporators, for efficient and stable solar evaporation.