Stability of sp3 Carbons in Hydrogenated Graphene Quantum Dots and Their Electronic and Optical Properties Studied Using Density Functional Theory
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Graphene quantum dots (GQDs) are zero-dimensional nanomaterials composed of sp 2 -hybridized carbon atoms, which are widely researched because of their tunable optical properties. GQDs contain defects, such as sp 3 -hybridized carbon atoms, which may be introduced during synthesis and can affect these materials’ properties. In this study, we use hydrogenated polycyclic aromatic hydrocarbons as models for GQDs containing sp 3 -hybridized carbon atoms. We analyze the effect of sp 3 carbons on the stabilities and electronic and optical properties of GQDs using density functional theory (DFT) and time-dependent DFT calculations. We find that sp 3 carbons can form stable arrangements as dimers or continuous chains along the edges of GQDs. Our results reveal that the presence of sp 3 carbons can tune the HOMO–LUMO gap, dependent on the position of sp 3 carbons within the GQD. Calculated optical absorption spectra show a reduction in intensity and a blue shift of the main absorption peak for most of the investigated sp 3 -containing structures; additionally, the presence of sp 3 carbons can extend the optical absorption of these structures into the red and infrared regions of the solar spectrum (600 to 900 nm), depending on the concentration and arrangement of sp 3 carbons. These results provide insight into structural factors responsible for the variation of the electronic and optical properties of GQD nanomaterials and suggest that controlling the amount of residual sp 3 carbon atoms introduced during synthesis can be used to tailor the properties of GQDs.
Authors: Nasiru Aminu Rano, Natalia Martsinovich
Institution: University of Sheffield
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4409521531