Structural and thermal stability of graphene oxide-silica nanoparticles nanocomposites

The investigation of the thermal stability up to 400 °C of Graphene Oxide (GO) and GO-silica nanoparticles (n-SiO₂) composites prepared by direct mixture of GO and n-SiO₂is reported. Using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Energy Dispersive X-ray analysis, Atomic Force Microscopy, Raman and Infrared absorption measurements a thorough characterization of the prepared materials is carried out. By deepening the changes induced in the 2D Raman spectral region of GO at about 2900 cm⁻¹the comprehension of an interplay, driven by the thermally induced changes of the material, between inter-valley and intra-valley vibrational transitions is elucidated. This result enables to find out that the major thermally induced changes are related to the GO counterpart of the nanocomposite and shows that the deposited silica nanoparticles are not interfering with the GO principal features exploiting the potentiality of nanocomposites preparation. Furthermore, silica nanoparticles are found to act as solid exfoliant agents, thus inhibiting GO lamellae re-aggregation even at high temperatures.