Enhanced organic gas sensing performance of Borophene/Graphene van der Waals heterostructures via transition metal doping

Borophene, a kind of novel two-dimensional nanomaterial, has garnered significant attention in recent years. In this study, we theoretically established a two-dimensional van der Waals heterostructure of borophene/graphene (B/G) by employing graphene as a substrate. We embarked on an exploration of the adsorption characteristics and sensing performance of this heterostructure concerning organic molecules: CH4, C2H4, C2H2, CH3OH, and HCHO. Based on the density functional theory (DFT), we performed the first-principles calculations to initially investigate the adsorption behaviors between the organic molecules and the borophene component of the heterostructure. The outcomes revealed weak physical adsorption interactions between the organic molecules and borophene. Building upon this understanding, we introduced transition metal (Sc, V, Cr, Mn, Fe, Co, and Cu) doping to the heterostructure, which shows significantly enhanced interactions between the system and the organic molecules. This augmentation in chemical interactions induced the changes in the hybridization of carbon atom orbitals within the organic molecules. In the context of chemical adsorption, employing the non-equilibrium Green's function method, we examined the sensing performance of the system. The results demonstrated the pronounced anisotropy of borophene, which can be observed even at extremely low bias voltages. Notably, the heterostructure exhibited heightened sensitivity towards C2H2. Consequently, the B/G heterostructure can serve as a promising candidate material for exceptional two-dimensional gas sensors.