Figure 2

Uniformity of functional groups and interconnected pores of the functionalized graphene cathode.

(a). EDS line-scanning demonstrated that the functional groups were uniformly distributed on the graphene surface. (b). A TEM image of the functionalized graphene cathode. (c). and (d). represent the EDS mapping images of C and O atoms in Figure 3b. (e). FE-SEM image of the functionalized graphene cathode, merging with O atoms acquired by EDS mapping analysis. FE-SEM images of the functionalized graphene cathode (f). at the surface (before FIB cutting) and (g). inside (after FIB cutting). To prevent damage from FIB cutting, Pt was deposited on the surface of the sample.