Formation and mechanism of ultrahigh density platinum nanoparticles on vertically grown graphene sheets by metal-organic chemical supercritical fluid deposition

An ultrahigh density over 1013 cm−2 of 2 nm diameter Pt nanoparticles was obtained by metal-organic chemical supercritical fluid deposition over the entire surface of vertically standing stacked graphene sheets (carbon nanowalls) on a substrate. The correlation between the surface defect density of graphene sheets and the density of Pt nanoparticles were investigated to clarify the support mechanism. The density of Pt nanoparticles increased with increase in the surface defect density. In addition, the semispherical cross-sectional shape of the nanoparticles indicated nucleation at the surface defects on the graphene sheets (98/100).