Fire-retardant anti-microbial robust wood nanocomposite capable of fire-warning by graded-penetration impregnation

Wood, renowned for its sustainability, specific strength, and thermal insulation, stands as a highly sought-after sustainable structural material. However, the inherent flammability, decay susceptibility, and inadequate mechanical strength hinder its practical applications in high-rise buildings. Here, we report a groundbreaking solution to fabricate multi-functional fire-retardant wood (M-FRW) through a coupled delignification/impregnation procedure followed by densification treatment. The GO/BA created a hybridized network on the M-FRW surface, while BA molecules penetrated the wood cell. As-created M-FRW exhibits a superior flame retardancy due to the physical barrier and catalytic charring effect of GO/BA, as reflected by an ultrahigh limiting oxygen index value of >75% and an 85% reduction in the peak of heat release rate compared to natural wood. Furthermore, the GO/BA layer of M-FRW has a sensitive fire alarm response and ultralong alarm time (∼11280 s). More impressively, M-FRW exhibits an exceptional ability to inhibit decay fungi, mold fungi, and common bacteria due to the superimposed anti-microbial effect of GO and BA. Additionally, M-FRW shows desirable mechanical and thermal insulation properties. This work provides a facile strategy to fabricate a multi-functional advanced wood nanocomposite, making them hold great potential for various engineering applications, such as intelligent buildings.