P-Doped g-C3N4/CoMoO4 Micro–Nano Structures for Fire-Safe Polypropylene Composites

Extended utilization of polypropylene (PP) is compromised by its high flammability. Owing to the merits of easy preparation and abundance in raw materials, graphitic-like carbon nitride (g-C3N4, denoted as CN) is favored as flame retardant for PP. Nevertheless, it is hard to acquire the satisfying flame retardancy efficiency when CN dosage is low. Here, the interfacial assembly strategy is utilized to obtain the micro–nano structure of phosphorus-doped CN/CoMoO4 (PCN–Co) as flame retardant for PP. When using 2.0 wt % PCN–Co, the decomposition temperatures are markedly enhanced, confirming the delayed thermal degradation. Peak heat release rate and total heat release values are impaired by 33.6 and 12.0%, implying the inhibited release of heat. Peak smoke production rate and total smoke production values are dampened by 45.1 and 34.9%, signifying hindered emission of smoke. In short, this work provides inspiration for the design of CN-based nanostructures, mining their potentials in polymer composite fields.