Skin-inspired multifunctional MXene/cellulose nanocoating for smart and efficient fire protection

• Multifunctional fire protection nanocoating (MFNC) was constructed via layer-by-layer. • MFNC exhibited accurate temperature-sensing performance. • MFNC could trigger the fire alarm less than 4 s when being burned. • MFNC exhibited outstanding flame retardancy and good self-healing performance. • MFNC showed good piezoresistive sensing capability. The development of flame-retardant coating with sensitive fire warning is imperative but highly challenging in the “Internet of Everything Era”. In this study, a multifunctional fire protection nanocoating (MFNC) was fabricated on the surface of flammable materials by dip-coating Ti 3 C 2 T X (MXene), montmorillonite (MMT) nanosheet, and 2-ureido-4[1H]-pyrimidinone-containing cellulose (UPC) via layer-by-layer assembly. The MXene/UPC layer endowed the nanocoating with accurate temperature sensing capability because of the outstanding conductivity and unique thermoelectric characteristic of MXene. When being burnt, MFNC was able to trigger the fire-warning system in less than 4 s. Owing to the MMT/UPC layer, MFNC showed excellent flame retardancy due to the barrier and catalytic carbonization of MMT. MFNC led to the increase in the limiting oxygen index of the flammable materials by up to 40.0% and the vertical burning test reached the UL94 V-0 rating. More importantly, attributed to the multiple hydrogen bond interactions of UPC, MFNC displayed good self-healing capability. Its fire-warning performance could quickly recover after being damaged. Furthermore, MFNC exhibited sensitive piezoresistive sensing ability, which makes it a promising candidate for application in firefighter motion detection. Our work provides new insights into the fabrication and application of multifunctional smart and efficient fire-protection coatings.