Synergistic Effect of GO and MXene Enables Ultrasensitive, Reversible, and Self-Powered Fire Warning of a GO/MXene/Chitosan Aerogel

Graphene oxide (GO)-based fire alarm materials have garnered extensive attention because the thermal reduction of GO to reduced GO (RGO) enables rapid fire warning. However, they suffer from poor flame retardancy, irreversible fire warning, and dependence on an external power supply. Herein, a GO/MXene/chitosan aerogel with a low density of 0.018 g cm^-3 and good compressibility has been developed. The experimental results demonstrate that (i) MXene effectively reduces the peak and mean heat release rate of GO, while RGO nanosheets compensate for the structural instability of MXene in the flame due to thermal oxidation into TiO₂; as such, long-lasting fire warning (>120 s) has been achieved; (ii) the reducibility and conductivity of MXene contribute to the ultrasensitive response of GO, with a fire response time of 1 s; and (iii) notably, the thermoelectric effect of MXene enables the reversible and self-powered fire warning of the GO/MXene/CS aerogel without an external power supply. Compared to pure MXene/CS aerogel, the presence of GO improves the sensitivity and stability of self-powered fire warning, owing to the formation of the highly conductive RGO nanosheets. The results of this work highlight the cooperation between GO and MXene in realizing ultrasensitive, long-lasting, reversible, and self-powered fire warning.