Argon diffusion in graphene oxide and reduced graphene oxide foils

Measurements of argon diffusion coefficient vs. temperature in graphene oxide (GO) and reduced graphene oxide (rGO) have been performed. GO and rGO foils have been employed with a thickness of 15 μm. GO has been reduced in vacuum at a temperature of 130 ◦C for 30 min. Measurements have been obtained by controlling the gas pressure gradient applied to two faces of the thin foils versus the time and the temperature. The measured Ar diffusion coefficients have been compared to those obtained for N2 in the same foils. In particular, the calculated room temperature Ar and N2 diffusion coefficients in GO are 2.95 × 10− 3 cm2/s and 0.168 × 10− 3 cm2 /s respectively. At 100 ◦C in rGO the Ar and N2 diffusion coefficients are 2.15 × 10− 3 cm2/s and 0.4 × 10− 3 cm2/s respectively. Consequently, the Ar diffusion coefficients in GO and rGO appear greater than the nitrogen ones. The high diffusion coefficient of Ar increases with the temperature and decreases going from GO to rGO, due to the highest compactness and density of the reduced GO foil. The smaller diffusion coefficient of N2 increases both with the temperature and going from GO to rGO, due to the partial water molecules and oxygen functional groups removal. The obtained results, their correlation with the inner structure of the graphene sheets and the comparison with the literature data are presented.