Topic: Nitrogen doped graphene investigated by scanning tunnelling microscopy
Speaker: Jérôme Lagoute (Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS, Université Paris Cité, Paris, France)
Abstract: Graphene, a single atomic layer of carbon atoms, exhibits extraordinary physical properties. To further enhance its versatility, some efforts are focusing on tailoring its physical and chemical characteristics through controlled modifications. Defect engineering is a promising route to reach that objective. One promising approach is chemical doping, where foreign atoms replace some carbon atoms within the graphene lattice. Nitrogen doping, in particular, has garnered significant attention due to its potential to significantly alter graphene's electronic properties [1].
We have explored the impact of nitrogen doping of graphene using scanning tunnelling microscopy. Nitrogen doping induces a global effect in graphene, consisting of n-type doping leading to a rigid shift of the bandstructure. This effect can be exploited to realize band engineering [2]. The nitrogen atoms also modify the properties of graphene at the local scale. At the location of the doping sites, resonant states appear in the electronic spectrum which can be thought as a possible way to modify the chemical. We probed this by investigating the electronic interaction of organic molecules with graphene. More complex defect engineering can be achieved by combining different types of defects. This was recently achieved through the combination of nitrogen doping and vacancy creation in graphite [3]. The nitrogen was used to position the charge neutrality point while vacancies were used to create a resonant state at this energy, which may be interesting to tune the chemical activity of defect sites.
These findings highlight the potential of defect engineering to tailor the properties of graphene and potentially 2D materials in general. More complex configurations can be explored in the future.
1 F. Joucken, L. Henrard and J. Lagoute, Phys. Rev. Materials 3, (2019) 110301
2 M. Bouatou et al., Advanced Functional Materials 32, 2208048 (2022)
3 D. Demba et al., Chem Phys Chem e202400221 (2024)
Zoom link: https://espci.zoom.us/j/81945226093?pwd=moFmLMgj0L2nyyxYQWcu5KrcXwccyu.1
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