Thermal effusion of water and carbon oxides from multilayered graphene oxide thin films

We report on water (H₂O) and carbon oxides (CO and CO₂) effusion from multilayered graphene oxide (GO) films during thermal reduction. The effusion of molecules was monitored through the thermal desorption spectroscopy (TDS) technique in films prepared by evaporating a colloidal solution of GO. This method reduces the presence of adsorbed/trapped H₂O molecules between adjacent GO planes. That allows the observation of additional effusion mechanisms. Thermal reduction process, from room temperature to ~ 1000 °C, was performed in a high-vacuum system with a mass spectrometer to monitor the outgassed species. A collective outgassing of H₂O, CO₂, CO species is observed and centered at approximately 230 °C. Above 400 °C, CO₂ and CO are the only observed outgassed species. Multiple origins for water outgassing were inferred from the TDS spectrum asymmetry, revealing an intricate superposition of mechanisms. The thermal treatment also reduces both the GO interlayer separation and the film surface roughness.