Effect of point defects in armchair graphene nanoribbons for biosensing of Methanethiol biomarkers: A DFT Study

In this study, we probe the surface engineered (vacancy and Stone Wales defective) hydrogen passivated armchair graphene nanoribbon with a width of 7 atoms as a biosensing material to detect methanethiol biomarkers. Induction of defects results in the decrement of the bandgap by the formation of the trapping states. After geometry optimisation, it is found that only vacancy induced armchair graphene nanoribbon can form strong binding with the biomarker, whereas Stone Wales defect induced armchair graphene nanoribbon show disassociation with the biomarker by having positive adsorption energy. Using density functional theory, the electronic properties of a vacancy-induced armchair graphene nanoribbon with and without adsorption of methanethiol are calculated, showing that methanethiol adsorption leads to increment in the bandgap of the host material by eliminating the trapping states. The work function and electron affinity change after adsorption. As there are significant changes in the electronic properties, vacancy induced armchair graphene nanoribbon show high sensing capabilities toward methanethiol biomarkers.