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A novel strategy for efficient growth of nitrogen-doped graphene (N-graphene) on a large scale from s-triazine molecules is presented. The growth process has been unveiled in situ using time-dependent photoemission. It has been established that a postannealing of N-graphene after gold intercalation causes a conversion of the N environment from pyridinic to graphitic, allowing to obtain more than 80% of all embedded nitrogen in graphitic form, which is essential for the electron doping in graphene. A band gap, a doping level of 300 meV, and a charge-carrier concentration of ∼8×10(12) electrons per cm2, induced by 0.4 atom % of graphitic nitrogen, have been detected by angle-resolved photoemission spectroscopy, which offers great promise for implementation of this system in next generation electronic devices.

Atomically precise graphene nanoribbons (GNRs) can be fabricated via thermally induced polymerization of halogen containing molecular precursors on metal surfaces. In this paper the effect of substrate reactivity on the growth and structure of armchair GNRs (AGNRs) grown on inert Au(111) and active Cu(111) surfaces has been systematically studied by a combination of corelevel X-ray spectroscopies and scanning tunneling microscopy. It is demonstrated that the activation threshold for the dehalogenation process decreases with increasing catalytic activity of the substrate. At room temperature the 10,10′-dibromo-9,9′-bianthracene (DBBA) precursor molecules on Au(111) remain intact, while on Cu(111) a complete surface-assisted dehalogenation takes place. Dehalogenation of precursor molecules on Au(111) only starts at around 80 °C and completes at 200 °C, leading to the formation of linear polymer chains. On Cu(111) tilted polymer chains appear readily at room temperature or slightly elevated temperatures. Annealing of the DBBA/Cu(111) above 100 °C leads to intramolecular cyclodehydrogenation and formation of flat AGNRs at 200 °C, while on the Au(111) surface the formation of GNRs takes place only at around 400 °C. In STM, nanoribbons have significantly reduced apparent height on Cu(111) as compared to Au(111), 70 ± 11 pm versus 172 ± 14 pm, independently of the bias voltage. Moreover, an alignment of GNRs along low-index crystallographic directions of the substrate is evident for Cu(111), while on Au(111) it is more random. Elevating the Cu(111) substrate temperature above 400 °C results in a dehydrogenation and subsequent decomposition of GNRs; at 750 °C the dehydrogenated carbon species self-organize in graphene islands. In general, our data provide evidence for a significant influence of substrate reactivity on the growth dynamics of GNRs.

We report an element-specific investigation of electronic and magnetic properties of the graphene/Ni(111) system. Using x-ray magnetic circular dichroism, the occurrence of an induced magnetism of the carbon atoms in the graphene layer is observed. We attribute this magnetic moment to the strong hybridization between C π and Ni 3d valence band states. The net magnetic moment of carbon in the graphene layer is estimated to be in the range of 0.05 − 0.1