A DFT study on the curving of 4N-divacancy defected graphene quantum dots induced by an external electric field and the effects of metal-ion doping

Abstract

We conducted a study to examine the impact of an external electric field on the curvature of metal and divalent metal ion doped 4N divacancy-defected graphene quantum dots (4N-GQDs), utilizing Density Functional Theory (DFT). We considered six common metal species, namely Ca, Ca²⁺, Cr, Cr²⁺, Fe, and Fe²⁺. Our findings reveal that the curvature of metal and divalent metal ion-doped-4N-GQDs increases as the external electric field strength rises in both positive and negative directions. However, the direction of curvature is contingent upon the orientation of the electric field, which is perpendicular to the 4N-GQD plane. The curvature directions of metal and divalent metal ion-doped-4N-GQDs under positive and negative electric fields are opposite. It is interesting to note that the HOMO–LUMO gap of metal and divalent metal ion doped 4N-GQDs can be altered by applying an external electric field exceeding ±0.020 a.u. Within this context, the gap for 4N-GQDs doped with these ions typically spans from 1.64 to 2.98 eV, which is lower than that of GQDs and undoped 4N-GQDs. As a result, we advocate a technique to deliberately induce curvature for metal and divalent metal ion-doped 4N-GQDs, thereby altering their electronic properties through the application of an external electric field. These materials show substantial promise as anchoring materials for electronic devices.