Controllable healing of defects and nitrogen doping of graphene by CO and NO molecules

B. Wang and S. T. Pantelides

Phys. Rev. B 83, 245403 – Published 17 June 2011

Abstract

Controllable defect healing and N-doping in graphene would be very valuable for potential device applications. Here we report first-principles molecular-dynamics simulations that suggest a procedure with fast dynamics and low thermal budget. Vacancies can be healed by sequential exposure to CO and NO molecules. A CO molecule gets adsorbed at a vacancy site and a NO molecule subsequently removes the extra O by forming NO $_{2}$ . Controllable N-doping can be achieved by sequential vacancy creation (e.g., by an electron beam) and subsequent exposure to NO molecules at room temperature. A combination of CO and NO molecules can potentially provide simultaneous healing and doping at a desirable ratio. The proposed strategy introduces no extra defects and is promising for graphene-based materials in radiation environments.

Received 2 May 2011

DOI:https://doi.org/10.1103/PhysRevB.83.245403

Authors & Affiliations

B. Wang^1,* and S. T. Pantelides^1,2,3

¹Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
²Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
³Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

^*bin.wang@vanderbilt.edu

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 83, Iss. 24 — 15 June 2011

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Vacancy healing by a CO molecule. (a) Optimized structure of CO in tilted configuration, (b) the most stable configuration with O sitting above a C-C bond, (c)–(g) snapshots of MD simulation. The initial structure (c) converts to the most stable configuration (d) after 0.9 ps at 1000 K. NO molecules are introduced in (e), and a NO $_{2}$ molecule is formed after 4.8 ps at 500 K (f) and desorbs rapidly leaving pristine graphene (g). The energy gain diagram for the process (c)–(g) is shown in (h). The inset in (h) shows the reference energy, which is the sum of the total energy of graphene with vacancies and molecules in gas phase. C, N, and O atoms are colored gray, blue, and red, respectively. The unit cell adopted in the calculation is indicated by a dashed rectangle. The arrows are there to guide the eyes.Reuse & Permissions
Figure 2
Controllable N-doping by NO molecules. Optimized structure of NO in a tilted configuration (a), and the most stable structure with N embedded in graphene (b). (c)–(g) Snapshots of MD simulation. The initial structure (c) converts into the most stable configuration (d) after 1.8 ps at 500 K. The additional NO molecule in (e) forms a NO $_{2}$ molecule with the extra O atom on surface after 0.3 ps (f) and desorbs quickly leaving N-doped graphene (g). The energy gain diagram for the process (c)–(g) is shown in (h). The inset in (h) shows the reference energy.Reuse & Permissions
Figure 3
Divacancy healing by CO molecules. Optimized structure of divacancy (a), two CO molecules in the tilted configuration (b), and O sitting on the bridge configuration (c). (d)–(g) Snapshots of MD simulation. The initial structure (d) converts into the more stable configuration (e) after 0.3 ps at 1000 K, with an energy gain of 0.6 eV. Additional NO molecules are introduced. NO binds to one extra O atom by forming a NO $_{2}$ molecule after 0.2 ps at 500 K (f) and the NO $_{2}$ molecule desorbs quickly leaving one O atom occupying the bridge site (g). As shown in Fig. 1, the left O atom can be removed similarly by a NO molecule, resulting in a perfect graphene sheet (h).Reuse & Permissions
Figure 4
NH $_{3}$ adsorption on graphene with a single vacancy. (a) and (b) Tilted and bridge configurations, (c)–(g) snapshots of MD simulation. The initial structure (c) converts to a bridge configuration (d) after 1.6 ps at 1000 K. Further annealing to 8 ps induces no change of the structure (e). After annealing at 1500 K for 10.4 ps, one H moves to a C1 atom (red) by forming a CH $_{2}$ group (f), and the last H attached to N transfers to a C2 (cyan) atom after 14.8 ps (g). (h) The energy gain diagram for the process (c)–(g). The inset in (h) shows the reference energy. Visualization of the MD simulation was carried out using the VMD program.[62]Reuse & Permissions
Figure 5
Schematic view of the vacancy healing and N-doping process of graphene with vacancies ( $V$ ) by CO and NO molecules.Reuse & Permissions

Physical Review B

covering condensed matter and materials physics