High gas sensing performance of inorganic and organic molecule sensing devices based on the BC 3 N 2 monolayer.

Recently, a novel two-dimensional (2D) BC 3 N 2 monolayer has gained a lot of attention due to its graphene-like structure, and it was first reported by using the particle swarm optimization algorithm and ab initio calculations. Combining density functional theory with the non-equilibrium Green's function method, a 2D BC 3 N 2 -based nanodevice has been theoretically constructed and the gas sensing performance of the BC 3 N 2 monolayer for inorganic and organic molecules has been extensively investigated. The results revealed that the BC 3 N 2 monolayer remains metallic with thermodynamic stability. Meanwhile, the results of sensing performance analysis show that the inorganic molecules CO, NO, and NO 2 and organic molecules C 2 H 2 and HCHO have strong chemical interactions with BC 3 N 2 and were chemically adsorbed onto BC 3 N 2 . In contrast, the interactions between NH 3 , SO 2 , CH 4 , C 2 H 4 and CH 3 OH and BC 3 N 2 are very weak and these molecules adopt physical adsorption. In the case of chemisorption, the electronic transport behaviors of the 2D BC 3 N 2 devices are sensitive to molecules, and the gas sensitivity of BC 3 N 2 is strongly anisotropic, especially for organic C 2 H 2 with the gas sensing ratios from 7.30 to 10.43 (from 2.51 to 2.79) under different bias voltages along the zigzag (armchair) direction. For inorganic molecules, the gas sensing device is not particularly sensitive, and the maximum gas sensing ratio is only 1.36 for CO. Meanwhile, the large anisotropic gas sensitivity can reach up to 2.66/6.22 for electron transport along the armchair and zigzag directions for CO/C 2 H 2 in the BC 3 N 2 -based sensing devices. Accordingly, the high gas sensitivity can be disclosed by displaying the scattering state around the Fermi level at different bias voltages during the transport process. As a result, BC 3 N 2 could be used in 2D gas sensing devices, especially for sensing organic molecule C 2 H 2 .