A multifunctional wood fiber aerogel that combines lightweight, hydrophobic, and exceptional flame-retardant properties, enabling reliable remote fire detection

Biomass aerogels, with their unique three-dimensional porous structure and renewable nature, have attracted widespread attention in fields such as thermal insulation, flame retardancy, smart sensing, and wearable devices. However, they face bottlenecks such as flammability, low mechanical strength, and poor water resistance under certain conditions, which severely limit their practical applications. In this study, we fabricated a multifunctional sodium carboxymethyl cellulose/graphene oxide/ammonium polyphosphate (CMC/GO/APP) composite aerogel with an anisotropic porous structure through unidirectional freeze-casting combined with silane cross-linking. When exposed to a flame, the composite aerogel triggers an alarm within 3.6 s. The organosilane modification endows the cross-linked network formed in the composite aerogel with excellent mechanical properties and a hydrophobic surface, resulting in a water contact angle of 145.8°. Comparison with the original CMC aerogel shows that the composite aerogel exhibits a 31.6% reduction in heat release rate and a 44.2% reduction in total heat release, demonstrating excellent flame-retardant properties. This aerogel features a synergistic mechanism that integrates flame retardancy, hydrophobicity, and fire early warning capabilities, showcasing significant application potential across multiple fields.