Adsorption of toxic gas molecules on pristine and transition metal doped hexagonal GaN monolayer: A first-principles study

Abstract

Abstract Using the first-principles calculations based on density functional theory (DFT-D2 method), we systematically study the structural, energetic, electronic and magnetic properties of toxic gas molecules (H2S, NH3 and SO2) adsorbed on pristine and transition metal (TM) atom (Fe, Mn) doped GaN monolayer (GaN-ML). The results show that the H2S and NH3 are physisorbed on pristine GaN-ML with small adsorption energy, charge transfer, and long adsorption distance. While chemical adsorption character of SO2 on GaN-ML can be obtained, which means that the pristine GaN-ML is sensitive to SO2. We find that the adsorption ability of pristine GaN-ML can be improved by introducing TM dopants. TM (Fe, Mn) doping can increase adsorption energy and charge transfer of the adsorbed systems, except for SO2 adsorbed Fe doped GaN-ML. The enhancing interaction between adsorbed molecules and the TM doped GaN-ML can dramatically induce electrical conductivity changes. Therefore, the TM doped GaN-ML is more suitable for gas molecules detection compared with the pristine GaN-ML. These present properties of gas molecules adsorbed on the pristine and TM doped GaN-ML will help to guide scientists to develop better two-dimensional GaN-based gas sensors in the future.