Connecting Dopant Bond Type with Electronic Structure in N-Doped Graphene

Abstract

Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.

Stabilizing graphene-based organometallic sandwich structures through defect engineering

“…As expected, the simple substitutional nitrogen electron-dopes graphene. The values for work function reported here are consistent with those obtained earlier by others (for example, see Schiros et al [37]), with the differences attributable to the choice (=difference in total energies of spin-unpolarized and spinpolarized states) for the graphene sheet without and with inplane defects (6 × 6 × 1 supercells). N.M. in the last column means that the structure is non-magnetic.…”

“…Three of its five valence electrons are involved in three σ-bonds with the neighboring carbons, one electron is donated to the π-network, and the last electon n-dopes the graphene web [37]. We have also studied two pyridinic defects: 1N C -V C that results in a structure with the C 2v symmetry [ Figure 1(d)], and the 3N C -V C -defect (D 3h symmetry) as shown in Figure 1(e).…”

Electronic Structure Modification of Ion Implanted Graphene: The Spectroscopic Signatures of p- and n-Type Doping

“…All the predictions on the exact effect of the incorporated dopant atoms in graphene suggest that the resulting band structure depends on the density and periodicity (or not) of the dopant atoms in the graphene lattice, 18,[20][21][22] as well as on the presence of adjacent defects. [23][24][25][26] To add to the complexity of the situation, the synthesis conditions of doped graphene, which most commonly follow the chemical route, yield graphene samples of varying quality, 17 often with several types of dopant atom and defect configurations within the same specimen. [25][26][27] In a bid to produce uniformly6doped single6 layer graphene specimens, the successful implementation of low6energy ion implantation with either N or B was recently demonstrated, [28][29][30] achieving retention levels of the order of ~1% in good agreement with theoretical predictions.…”

Chemically modified graphene and nitrogen-doped graphene: Electrochemical characterisation and sensing applications

“…will result in n-type characteristics whereas an electron deficient atom like B induces a p-type characteristics, both of which cause an increase in free charge carriers in the graphene framework, thereby enhancing conductivity. Hence tuning the band gap by chemical doping enhances the charge carrier concentration [18] and leads to promising applications in semiconductor electronics such as field effect transistors [11], and as electrocatalyst in the oxygen-reduction reaction (ORR) in fuel cells and in sensors [19].…”

“…The Ndoping of graphene has been done by thermal annealing in the presence of ammonia and the nitrogen atom in the graphene framework can exist in "graphitic", pyridinic or pyrrolic forms, each of which can provide different characteristics to the graphene framework [19,20]. Pure and N-graphene were compared with their derivatives, which were acidic (HNO 3 ) or basic (KOH) functionalized G and NG [21,22].…”