The
limitations of graphene as an effective corrosion-inhibiting coating on meta
l surfaces, here exemp
lified by the hex-reconstructed Pt(100) surface, are probed by scanning tunne
ling microscopy measurements and density functiona
l theory ca
lcu
lations. Whi
le exposure of sma
ll mo
lecu
les direct
ly onto the Pt(100) surface wi
ll lift the reconstruction, a sing
le graphene
layer is observed to act as an effective coating, protecting the reactive surface from O
2 exposure and thus preserving the reconstruction underneath the graphene
layer in O
2 pressures as high as 10
鈥? mbar. A simi
lar protective effect against CO is observed at CO pressures be
low 10
鈥? mbar. However, at higher pressures CO is observed to interca
late under the graphene coating
layer, thus
lifting the reconstruction. The
limitations of the coating effect are further tested by exposure to hot atomic hydrogen. Whi
le the coating can withstand these extreme conditions for a
limited amount of time, after substantia
l exposure, the Pt(100) reconstruction is
lifted. Annea
ling experiments and density functiona
l theory ca
lcu
lations demonstrate that the basa
l p
lane of the graphene stays intact and point to a graphene-mediated mechanism for the H-induced
lifting of the reconstruction.
Keywords:
graphene; coating; STM; hydrogen; CO; O2