Robust ambient-stable 2D heterostructure of copper oxides intercalating black phosphorus for flame retardancy and catalytic removal of carbon monoxide

Two-dimensional black phosphorus (2D BP) utilized in flame retardant applications frequently encounters significant challenges, including inadequate ambient stability and elevated carbon monoxide (CO) release rates. To mitigate these issues, an effective approach was proposed for the fabrication of 2D heterostructures comprising copper oxide intercalated with BP in this work. This methodology takes into account both thermodynamic and kinetic factors, resulting in substantial enhancements in the ambient stability of BP and the catalytic performance for CO elimination, achieved through the synergistic interactions between 2D BP and copper oxide, all while preserving the structural integrity of 2D BP. The incorporation of gelatin and kosmotropic anions facilitated the efficient adhesion of the multifunctional heterostructures to the flammable flexible polyurethane foam (FPUF), which not only scavenged free radicals in the gas phase but also catalyzed the formation of a dense carbon layer in the condensed phase. Kosmotropic anions induce a salting-out effect that fosters the development of a chain bundle, a hydrophobic interaction domain, and a potential microphase separation region within the gelatin chains, leading to a marked improvement in the mechanical strength of the heterostructure coatings. The modified FPUF exhibited a high limiting oxygen index (LOI) value of 34%, alongside significantly improved flame resistance: the peak CO release rate was reduced by 78%, the peak heat release rate decreased by 57%, and the fire performance index (FPI) was increased by 40 times compared to untreated FPUF. The 2D heterostructure coatings demonstrated better CO catalytic removal performance relative to previously reported flame retardant products. This research offers a promising design principle for the development of next-generation high-performance flame retardant coatings aimed at enhancing fire protection. In this work, an effective approach was proposed to fabricate 2D heterostructures of copper oxide intercalated with BP, which not only enhances flame retardancy but also improves the ambient stability of BP and the catalytic performance for CO elimination. • A novel approach was proposed for making an ambient-stable heterostructure of copper oxides intercalating 2D BP. • Heterostructure coatings exhibit high flame retardant efficiency and CO catalytic removal performance. • “Soft” and “hard” states of the heterostructure coatings could be actively switched by ion-specific effects. • Fire performance index of treated FPUF was increased by 40 times compared to previously reported products.