Fig. 2
Growth of metre-scale, super-clean graphene. a Schematics of the experimental design, i.e., the Cu foil-foam stacked structure, for the growth of super-clean graphene. Inset: Illustration of interaction of Cu and methane in the gap between Cu foil and foam. b AFM image of the freshly prepared clean graphene on Cu foil after growth. c TEM image of the super-clean graphene membrane. Inset: HRTEM image of the graphene lattice. d Number of TiO2 particles adsorbed on super-clean graphene at different positions and on unclean graphene. The error bar represents the relative deviation. Inset: photograph of metre-scale, super-clean graphene after TiO2 visualisation. e Raman spectra of the carbon species (C sp.) on Cu nanoparticles collected in boundary layer during CVD growth, with (red line) and without (blue line) the assistance of Cu foam. The nanoparticles were collected on quartz substrates (see details in supporting information). The yellow and blue rectangles represent amorphous carbon and graphene-related Raman peaks, respectively
