Detection of harmful gases (NO, NO2) by GaN@MoSSe heterostructures embedded with transition metal (Cu, Fe and Mn) atoms: A DFT study

Monitoring and identifying air pollutants, such as NO and NO₂, is crucial due to their detrimental impact on both the environment and human health. This work employs density functional theory (DFT) with the PBE + U functional to investigate the adsorption and sensing performance of NO and NO₂ on transition metal (TM)-doped GaN@MoSSe heterostructures. The adsorption energy, charge transfer, electron localization functions, charge density difference, spin density, band gaps and density of states are analyzed. The findings reveal that a transition from physisorption to chemisorption occurs after TM atoms doping. Also, when the surface is embedded with Cu, Fe and Mn atoms, there is a significant improvement in the behavior related to gas adsorption. The bandgap and its variations lead to the change in surface electrical conductivity, thereby affecting the gas sensitivity of the adsorption system. Particularly, the Cu_Ga-GaN@MoSSe and Fe_Ga-GaN@MoSSe systems exhibit improved gas sensitivity toward NO due to their significant band gap reduction. Meanwhile, the Cu_Se−MoSSe@GaN, Cu_Ga-GaN@MoSSe, Fe_Ga-GaN@MoSSe and Mn_Ga-GaN@MoSSe systems also demonstrate enhanced sensing capabilities for NO₂. This work offers valuable theoretical insights for exploring the potential applications of TM-GaN@MoSSe heterostructures in gas sensing.