Insight into CO₂ Etching Behavior for Efficiently Nanosizing Graphene

Chemical etching of graphene over catalytic metal surface holds great potential in nanosizing the graphene microstructure and thus modulating its properties. Herein, it has been demonstrated that gaseous CO₂ can efficiently etch the monolayer graphene film grown by chemical vapor deposition catalyzed with the surface of Cu foil. During the etching process, the CO₂ etching rate is monotonously dependent on the CO₂ flowrate and the etching temperature, and is faster than the H₂ etching which has been usually employed for the graphene patterning. Moreover, the resultant graphene flakes by the CO₂ etching remain the originally high crystallinity and are free of being oxidized. Also, a 120° angle between the neighboring edges and hexagonal morphology of graphene flakes can be realized for the potential shape regulation of nanostructured graphene, which is similar as the anisotropic etching of H₂. These results illustrate that the CO₂ etching over the metal surface can provide a promising strategy for the precisely fabrication of nanostructured graphene materials.