SEM images of carbon powder samples on a carbon TEM microgrid. (a) and (b) FePt@CNC and GNS mixture following hydrogen peroxide oxidation and aqua regia treatment. (c) and (d) Magnetically separated GNSs. Enlarged views of (b) FePt@CNCs and (d) an individual graphite nanosheet with a crumpled structure and folded central regions indicated by arrows.