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

Graphene oxide (GO)-based fire alarm materials have garnered\nextensive\nattention because the thermal reduction of GO to reduced GO (RGO)\nenables rapid fire warning. However, they suffer from poor flame retardancy,\nirreversible fire warning, and dependence on an external power supply.\nHerein, a GO/MXene/chitosan aerogel with a low density of 0.018 g\ncm<sup>–3</sup> and good compressibility has been developed.\nThe experimental results demonstrate that (i) MXene effectively reduces\nthe peak and mean heat release rate of GO, while RGO nanosheets compensate\nfor the structural instability of MXene in the flame due to thermal\noxidation into TiO<sub>2</sub>; as such, long-lasting fire warning\n(>120 s) has been achieved; (ii) the reducibility and conductivity\nof MXene contribute to the ultrasensitive response of GO, with a fire\nresponse time of 1 s; and (iii) notably, the thermoelectric effect\nof MXene enables the reversible and self-powered fire warning of the\nGO/MXene/CS aerogel without an external power supply. Compared to\npure MXene/CS aerogel, the presence of GO improves the sensitivity\nand stability of self-powered fire warning, owing to the formation\nof the highly conductive RGO nanosheets. The results of this work\nhighlight the cooperation between GO and MXene in realizing ultrasensitive,\nlong-lasting, reversible, and self-powered fire warning.