Mass spectrometry of graphene oxide thermal reduction in vacuum

Foils of graphene oxide (GO) prepared by micrometric graphene oxide platelets dispersed in water at low concentrations were physically investigated during their thermal reduction in a vacuum. The water, the carbon dioxide and the functional groups of oxygen, degassed during the thermal treatment, were monitored for the first time with a quadrupole mass spectrometer as a function of the foil temperature. Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-rays (EDX) analyses were also presented to confirm the modality of reduction in vacuum. The thermal reduction process increases the C/O atomic ratio from the pristine value of about 2.0 to about 4.5 using a temperature of about 200°C. The reduced graphene oxide (rGO), depleted of water and some functional oxygen groups, shows a more compact structure with an increment of the density from the pristine value of about 1.36 g/cm3 to about 1.9 g/cm3, which determines a decreasing of the distance between the graphene layers.