In Situ Construction of Molybdenum Disulfide/Metal‐Phenolic Network Hybrid Brick‐and‐Mortar Structures for Interfacial Reinforcement of Carbon Fiber/Epoxy Composites

ABSTRACT Enhancing the fiber–matrix interfacial bonding is essential for fully exploiting the performance of carbon fiber/epoxy (CF/EP) composites. In this work, a nacre‐inspired strategy was proposed by integrating molybdenum disulfide (MoS ₂ ) nanosheets with a metal‐phenolic network (MPN) to construct a hierarchical “brick‐mortar” interphase. MoS ₂ nanosheets were in situ grown on the carbon fiber surface as rigid bricks, which not only increased surface roughness and provided abundant anchoring sites but also facilitated crack deflection. Subsequently, a flexible MPN layer was deposited as the mortar, introducing strong adhesion and energy‐dissipation capacity through hydrogen bonding, π–π interactions, and Fe ³⁺ ‐tannic acid coordination. Mechanical tests demonstrated that this “brick‐mortar” interphase significantly enhanced composite performance. Compared with pristine CF/EP composites, the interlaminar shear strength, flexural strength, and transverse tensile strength were improved by 19.2%, 82.1%, and 32.6%, respectively. The synergistic integration of rigid MoS ₂ and flexible MPN effectively suppressed interfacial debonding and ensured efficient stress transfer, thereby providing a practical and scalable strategy for interfacial reinforcement of high‐performance polymer composites.