Mo₂C Supported by Oxidized Carbon Nanotubes for Reinforcing Epoxy Composite

It is crucial to weaken the influence of sacrificing the mechanical properties of epoxy matrices by enhancing the efficiency of flame retardants. Herein, we utilized oxidized carbon nanotube (oCNT) as a dual-functional component, serving as both carbon sources and supports for Mo2C nanoparticles, and effectively modified N species to oCNT, improved the dispersion of Mo2C, and combined Mo2C with oCNT simultaneously. The physical and chemical properties of the resulting Mo2C@oCNT were characterized. Remarkably, the incorporation of merely 0.18 wt % Mo2C in the epoxy composite yielded simultaneous and significant improvements in mechanical and flame-retardant properties. The composite exhibited substantial enhancements in key mechanical parameters, with tensile strength, impact strength, and storage modulus increasing by 6.5, 38.1, and 10.5%, respectively. Concurrently, the flame retardancy performance showed marked improvement, as evidenced by a 12% increase in the limiting oxygen index, an 8.6% extension in time to peak heat release rate, and a 52.5% elevation in char yield. Furthermore, critical fire safety parameters demonstrated significant reduction, with the peak heat release rate, total heat release, and total smoke production decreasing by 19.2, 10.2, and 12.7%, respectively. Mo2C@oCNT/epoxy nanocomposite exhibited the lowest fire growth rate value of 5.05 kW·m–2·s–1. The enhanced mechanical performance was attributed to the strong and extensive interfacial interactions that facilitated efficient stress transfer from the epoxy matrix to the strong Mo2C@oCNT. The superior catalytic dehydrogenation performance of Mo2C contributed to carbonization and forming protective chars during combustion, leading to enhanced flame retardant performances of Mo2C@oCNT/epoxy nanocomposite. This work presents a promising strategy for developing high-performance epoxy nanocomposites with balanced mechanical and flame-retardant properties through rational nanohybrid design.