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.