Cracked Metal–Phenolic Networks with Durable Confinement Capillarity for Enhanced Solar Desalination

Abstract Solar‐driven interfacial desalination is a promising strategy to address freshwater shortages. Water evaporation can be enhanced through confinement capillarity by generating ultra‐thin water layers on the internal surfaces of porous photothermal materials. However, realizing confinement capillarity relies on coatings composed of aggregated nanospheres, which likely detach under mechanical compression, limiting their practical application. Herein, nature‐inspired crack patterns are introduced into adhesive photothermal supramolecular materials, metal–phenolic network coatings, forming C‐MPNs to achieve durable confinement capillarity. The crack patterns can be controlled to optimize water transport through narrow channels, enhancing the evaporation rate from 1.6 to 3.3 kg m −2 h −1 while preventing salt accumulation during seawater desalination. Furthermore, the cracks serve as buffer zones, significantly improving the mechanical stability of C‐MPN coatings under compression (exhibiting negligible change after 300 cycles)—overcoming a key challenge that has hindered the practical application of confinement capillarity. Furthermore, due to the enhanced confinement capillarity in C‐MPNs, high evaporation performance is sustained even as the size of the photothermal material increases—a rare characteristic among 3D photothermal materials. This work provides fundamental insights into the design of photothermal coatings with confinement capillarity, paving the way for their application in solar desalination.