The topography and morphology of the as-prepared materials
were observed by AFM, FESEM, and TEM (Figs. 2 and 3,
Supplementary material Fig. S1). The AFM images and the corresponding
height profiles of graphene and graphene/TiO2-0.86%
are shown in Fig. 2. From Fig. 2a, the height of graphene is about
0.4 nm, which is almost the same as the theoretical height (0.34 nm)
of single-layer graphene [46]. This result suggests that the single
layer graphene was successfully fabricated by ultrasonic exfoliation
and hydrothermal reduction. From Fig. 2b, the height of