Divacancy graphene and graphyne as potential biomedical sensors: A first-principles study

Imbalance in the levels of hydrogen peroxide signals the onset of chronic diseases in our body. Thus, it becomes imperative to design simple material systems with single molecule sensitivity. In this study, we investigate graphene and graphyne based systems by including various vacancy structures to assess their potential as H₂O₂ sensor materials. From the computed adsorption energies, we select two promising candidates, interestingly both are divacancies in graphene and graphyne. We then investigate electron transport in both the systems using the DFT-NEGF approach. Upon adsorption of H₂O₂ on the 585 vacancy (a special case of divacancy) in graphene and divacancy graphyne monolayers, we observe distinguishing current-voltage and electron transmission characteristics, in particular, in the former. For the 585 divacancy graphene system through analysis of the electronic properties, we identify the underlying mechanisms responsible for the difference in current values between the clean and H₂O₂ adsorbed systems, and hence its sensing ability. This work opens up a new avenue of intelligently incorporating vacancy defects in cheaper carbon-based 2D materials to effectively serve as potentially highly sensitive and selective biosensors for early disease detection.