Fig xA The Raman spectra of

But in the present study, the formation of NiO nanoparticles brings oxygen element in the composites, and the NiO contents in the composites are completely different. Thus, the carbon-to-oxygen ratios of as-obtained G/NiO composites are irregular. To avoid the interference of NiO, we recorded the high-resolution C1s spectrum and tried to evaluate the reduction degree of graphene by using the intensity ratios of CC bond and CO bond.