Thermal stability of functionalized carbon nanotubes studied by in situ transmission electron microscopy

► The first study of thermal stability of functionalized carbon nanotubes using in situ transmission electron microscopy. ► The thermal stability of the functionalized CNTs was found significantly reduced during the in situ heating process. ► The average diameter dramatically expanded from RT to about 500 °C, and then tended to be stable until about 1000 °C. ► EDS analysis suggested coalescence of carbon structure instead of deposition with foreign elements during heating process.