Bio-inspired, sustainable and mechanically robust graphene oxide-based hybrid networks for efficient fire protection and warning

Effective utilization of natural biomass-derivatives for developing sustainable, mechanically robust, and fireproof materials remains a huge challenge in fire safety and prevention field. Herein, based on bionic design, the hybrid interconnected networks composed of two-dimensional (2D) graphene oxide (GO) nanosheets, renewable one-dimensional (1D) phosphorylated-cellulose nanofibrils (P-CNFs) and tannic acid molecules (TA) were prepared via a green and facile evaporation-induced self-assembly strategy. Through construction of the multiple synergistic interactions among the TA, P-CNFs and GO, the optimized 1D/2D interconnected networks with hierarchical nacre-like structure were achieved and exhibited improved mechanical properties (tensile strength and Young’s modulus up to ∼ 132 MPa and ∼ 7 GPa, i.e. ∼ 3.6 and ∼ 14 times higher than that of the pure GO paper), good structural stability in various environments (aqueous solutions with different pH values), excellent flame retardancy (keeping structural integrity after flame attack), and ultrasensitive fire alarm functions (e.g., ultrafast flame alarm time of < 1 s and sensitive fire warning responses). Further, such 1D/2D interconnected networks can act as effective flame-retardant nanocoatings to significantly improve the flame retardancy of combustible PU foam materials (e.g., ∼48% decrease in peak heat release rate at only 10 wt% content). Based on the structure observation and analysis, the related synergistic reinforcing and flame-retardant mechanisms were proposed and clarified. Clearly, this work provides a new route for design and development of environmentally friendly fireproof and fire alarm materials based on utilization of natural biomass-derivatives.