Folded graphene nanoribbon as a sensitive and selective gas sensor: first principles study

In recent years, graphene nanoribbon (GNR) has emerged as a promising new semiconducting substance due to its potential applications in nanoelectronics. Two types of GNRs; zigzag (ZGNR) and armchair (AGNR) have been investigated recently, where the latter is suitable for sensor applications due to its semiconducting properties. Moreover, a new configuration of AGNR, which is constructed by folding an AGNR over its width (FAGNR), has attracted significant attention due to its unique electrical properties. The potential applications of AGNR and FAGNR as gas sensors have been investigated in detail. In order to achieve stable atomic arrangement, each structure is relaxed up to a minimum energy construction. Using density functional theory, it is found that the interactions of CO, O₂ and CO₂ molecules with FAGNR are more than those with AGNR. Furthermore, based on non-equilibrium Green's function (NEGF), the current–voltage characteristics of the two aforementioned gas sensors are calculated and compared. It is demonstrated that FAGNR shows more resistive sensitivity and selectivity to CO₂ gas molecule even under normal atmospheric conditions, where FAGNR has already adsorbed O₂ gas molecules from ambiance. Consequently, it is deduced that FAGNR would open a new window for developing a selective and more efficient CO₂ resistive gas nanosensor. (paper)