▎ 摘　　要

Electron-beam irradiation (EBI) on a graphene oxide (GO) film resulted in a stepwise growth of carbon nanostructures from a few-layered graphitic- and stripe-like nucleation to embedded onions; the formation mechanism of these embedded onions is different from that of free onions. Further, EBI-induced reduction and size-dependent onion and nanodiamond formations were observed. The detailed in-situ observations reveal that the formation of unique carbon nanostructures results from a GO film's intrinsic properties related to slow reactivity with heat generation, thermodynamic stability, and a physically well-bound fiat reaction surface.