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Under near-ambient pressure conditions, carbon monoxide molecules intercalate underneath an epitaxial graphene monolayer grown on Ni(111), getting trapped into the confined region at the interface. On the basis of ab-initio density functional theory calculations, we provide here a full investigation of the intercalated CO pattern, highlighting the modifications induced on the graphene electronic structure. For a CO coverage as low as 0.14 monolayer (ML), the graphene layer is spatially decoupled from the metallic substrate, with a significant C 1s core level shift towards lower binding energies. The most relevant signature of the CO intercalation is a clear switching of the graphene doping state, which changes from n-type, when strongly interacting with the metal surface, to p-type. The shift of the Dirac cone linearly depends on the CO coverage, reaching about 0.9 eV for the saturation value of 0.57 ML. Theoretical predictions are compared with the results of scanning tunnelling microscopy, low-energy electron diffraction and photoemission spectroscopy experiments, which confirm the proposed scenario for the nearly saturated intercalated CO system. This result opens the way to the application of the graphene/Ni(111) interface as gas sensor to easily detect and quantify the presence of carbon monoxide. [Display omitted] • Carbon monoxide intercalated at Graphene/Ni(111) interface forms periodic patterns. • Graphene decouples from Ni(111) after intercalation of carbon monoxide. • CO intercalated at Graphene/Ni(111) interface switches the Graphene doping state. • CO intercalated at Graphene/Ni(111) interface shifts the Dirac cone up to about 1 eV. • Graphene/Ni(111) interface can be used as gas sensor for carbon monoxide. [ABSTRACT FROM AUTHOR]

The influence of different substrates on the photocarrier relaxation dynamics in monolayer graphene during the early stages of thermalization and cooling is explored and analyzed by means of ensemble Monte Carlo simulations. In addition, phonon dynamics of both intrinsic and surface polar modes associated to the interface between graphene and the underlying substrate are investigated. Suspended graphene and graphene on four of the most common substrates used for nanoelectronics will be studied, showing that depending on the case, carrier relaxation can be accelerated due to the leading role that the surface polar phonon modes take under such out-of-equilibrium situations. Among the considered cases, graphene on Al 2 O 3 shows the highest relaxation rates, while the results of graphene on h-BN, SiO 2 and SiC are quite similar. On its behalf, photocarriers in suspended graphene take longer to thermalize than any of the substrate supported cases. [ABSTRACT FROM AUTHOR]