In situ XPS Observation of Selective NOx Adsorption on the Oxygenated Graphene Films

Graphene derivatives are promising sensor materials due to their high surface area available for molecule adsorption and conductivity changes under the adsorbate impact. The selectivity of such materials can be tuned through the attaching of certain functional groups preferably interacting with the defined gases. In the present work, we compare the reactivity of graphene oxide, oxyfluorinated graphene, and fluorinated graphene toward gaseous NOx molecules. The interaction of the molecules with the graphene-based films was monitored by in situ X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy measurements. The spectra before and after exposure of the films to a gaseous NOx mixture detected equal concentrations of adsorbed NO2 and NO species on graphene oxide, the preferable interaction of oxyfluorinated graphene with NO2 and the absence of the adsorbed molecules on the fluorinated graphene surface. These results are useful for the development of selective graphene-based gas sensors.