High gas sensing performance of inorganic and organic molecule sensing devices based on the BC3N2 monolayer.

Abstract

Recently, a novel two-dimensional (2D) BC3N2 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 BC3N2-based nanodevice has been theoretically constructed and the gas sensing performance of the BC3N2 monolayer for inorganic and organic molecules has been extensively investigated. The results revealed that the BC3N2 monolayer remains metallic with thermodynamic stability. Meanwhile, the results of sensing performance analysis show that the inorganic molecules CO, NO, and NO2 and organic molecules C2H2 and HCHO have strong chemical interactions with BC3N2 and were chemically adsorbed onto BC3N2. In contrast, the interactions between NH3, SO2, CH4, C2H4 and CH3OH and BC3N2 are very weak and these molecules adopt physical adsorption. In the case of chemisorption, the electronic transport behaviors of the 2D BC3N2 devices are sensitive to molecules, and the gas sensitivity of BC3N2 is strongly anisotropic, especially for organic C2H2 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/C2H2 in the BC3N2-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, BC3N2 could be used in 2D gas sensing devices, especially for sensing organic molecule C2H2.