Susceptible Detection of Organic Molecules Based on C 3 B/Graphene and C 3 N/Graphene van der Waals Heterojunction Gas Sensors.

Constructing van der Waals (vdW) heterostructures is a prospective approach that is essential for developing a new generation of functional two-dimensional (2D) materials and designing new conceptual nanodevices. Using density-functional theory combined with a nonequilibrium Green's function approach allows for the theoretical and systematic exploration of the electronic structure, transport properties, and sensitivity of organic small molecules adsorbed on 2D C ₃ B/graphene (Gra) and C ₃ N/Gra vdW heterojunctions. Calculations show the metallic properties of C ₃ B/Gra and C ₃ N/Gra after the formation of heterojunctions. Interestingly, the heterojunctions C ₃ B/Gra (C ₃ N/Gra) for the adsorption of small organic molecules (C ₂ H ₂ , C ₂ H ₄ , CH ₃ OH, CH ₄ , and HCHO) at the C ₃ B (C ₃ N) side are sensitive to the chemisorption of C ₂ H ₂ and C ₂ H ₄ . Similarly, the Gra/C ₃ B is chemisorbed for both C ₂ H ₂ and C ₂ H ₄ when adsorbed on Gra side, while it is only chemisorbed for C ₂ H ₂ in Gra/C ₃ N. Interestingly, all heterojunctions on different sides are physisorbed for CH ₃ OH, CH ₄ , and HCHO. Furthermore, the calculated I-V curves demonstrate that the devices based on the adsorption of C ₂ H ₂ and C ₂ H ₄ at each side of the heterojunction have remarkable anisotropy, in with the current being considerably greater in the zigzag direction than in the armchair direction. More specifically, with C ₂ H ₂ adsorbed on the Gra side, the sensitivity along the armchair direction is up to 85.0% for Gra/C ₃ B and close to 100% for Gra/C ₃ N. This study reveals that C ₃ B/Gra (C ₃ N/Gra) heterojunctions with high selectivity, high anisotropy, and excellent sensitivity are highly prospective 2D materials for applications, which further contributes new insights into the development of future electronic nanodevices.