Topological junction states in graphene nanoribbons: A route to topological chemistry

Two-dimensional topological insulators with propagating topological edge states are promising for dissipationless transport, while their one-dimensional analogs are capable of hosting localized topological junction states that are mainly envisaged for quantum computing and spintronics. Here, in contrast, we propose to use the localized nature of topological junction states for sensing applications. We report a systematic topological classification of a wide class of graphene nanoribbons represented by already synthesized extended chevron species. Using this classification, we theoretically model a double junction transport that shows an enhanced interaction with the NO${}_2$ molecule. Our results show that topological junction states of nanoribbons can open an avenue for topological sensing and junction-assisted chemistry applications.