▎ 摘　　要

To gain the target functionality of graphene for gas detection, nonfocused and large-scale compatible MeV electron beam irradiation on graphene with Ag patterns is innovatively adopted in air for chemical patterning of graphene. This strategy allows the metal-assisted site-specific oxidation of graphene to realize monolithically integrated graphene-chemically patterned graphene (CPG)-graphene homojunction-based gas sensors. The size-tunable CPG patterns can be mediated by regulating the size of Ag prepatterns. The impacts of highly energetic electron irradiation (HEEI) on graphene are summarized as follows: (i) the selective p-type doping and the defect generation of graphene by the HEEI-induced oxidation, (ii) the resistance of the homojunction devices manipulated by the HEEI dose, (iii) the band gap opening of graphene as well as the lowering of the Fermi level, (iv) the work function values for pristine graphene and CPG corresponding to 4.14 and 4.88 eV, respectively, and (v) graphene-CPG-graphene homojunction for NO2 gas, revealing an 839% enhanced gas response compared with that of the pristine graphene-based gas sensor.