Toxic gas sensing performance of arsenene functionalized by single atoms (Ag, Au): a DFT study

The detection and removal of toxic gases from the air are imminent tasks owing to their hazards to the environment and human health. Based on DFT calculations with VdW correction, adsorption configurations, adsorption energies, and electronic properties were compared for the adsorption of toxic gas molecules (CO, NO, NO₂, SO₂, NH₃ and H₂S) on pure arsenene (p-arsenene) and Ag/Au-doped arsenene (Ag/Au-arsenene). Our calculations show that all molecules considered to chemisorb on Ag/Au-arsenene and the substitution of noble metal, particularly Ag, could remarkably enhance the interactions and charge transfer between the gas molecules and Ag/Au-arsenene. Thus, Ag/Au-arsenene is expected to show higher sensitivity in detecting CO, NO, NO₂, SO₂, NH₃ and H₂S molecules than p-arsenene. Furthermore, the changes in the vibrational frequencies of gas molecules and the work functions of Ag/Au-arsenene substrates upon adsorption are shown to be closely related to the adsorption energies and charge transfer between the molecules and Ag/Au-arsenene, which is dependent on the molecules. Therefore, Ag/Au-arsenene-based gas sensors are expected to show good selectivity of molecules. The analysis of theoretical recovery time suggested that Ag-arsenene shows high reusability while detecting H₂S, CO, and NO, whereas Au-arsenene has high selectivity to sensing NO at room temperature. With the increase in work temperature and decrease in recovery times, Ag/Au-arsenene could be used to detect NH₃ and NO₂ from factory emission and automobile exhaust with quite good reusability. The above results indicated that Ag/Au-arsenene shows good performance in toxic gas sensing with high sensitivity, selectivity, and reusability at different temperatures.