Dendritic borophene-guided reinforcement strategy for high-performance copper structural composites

The integration of two-dimensional (2D) materials into metal matrices represents a compelling strategy for creating next-generation structural materials with synergistic mechanical and functional properties. Among these, borophene offers exceptional theoretical stiffness (398 N/m), tunable electrical character, and structural polymorphism. However, the scalable synthesis of crystalline borophene and its practical integration into metal matrices remain formidable challenges. Here, we report a breakthrough bottom-up strategy for the controlled chemical vapor deposition (CVD) of large-scale, single-crystalline α′-4H-borophene directly on Cu (111) surface using B₂H₆ gas. By controlling growth kinetics, a dendritic borophene morphology is obtained to promote mechanical interlocking. This in-situ fabrication creates an integrated borophene/copper composite, exhibiting a remarkable simultaneous enhancement in both strength and stiffness. Compared with pristine copper, the borophene-reinforced composites show significant mechanical enhancements: a 71% increase in Young's modulus (113.5 to 194.3 GPa), 323% higher yield strength (69 to 292 MPa), and 43% greater ultimate tensile strength (228 to 325 MPa). These improvements exceed those of other reported 2D material-reinforced Cu composites, establishing borophene's potential for structural applications and offering a novel synthesis pathway for advanced metal-matrix composites reinforced with 2D materials.