Porous graphene oxide foams were prepared by unidirectional freeze-drying technology and used to investigate the reaction between graphene oxide (GO) and SO 2 . The structure and composition changes of the graphene oxide were monitored by X-ray photoelectron spectrometry (XPS), Raman, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV-vis), and the product of the reaction was analyzed by an EDTA titration. The results show that SO 2 was oxidized to SO 3 and the GO was reduced. GO not only acts as the oxidant in the reaction, but also as the catalyst to catalyze the reaction of SO 2 and O 2 to form SO 3 . This catalytic action is more active in the aqueous GO suspensions than in the foams. The GO foams can adsorb SO 2 and convert it to SO 3 which then changes to SO 4 2À on contact with water. This offers a new effective method of converting noisome SO 2 gas to SO 3 at room temperature.

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