Adsorption Behaviors of Small Molecules on Two-Dimensional Penta-NiN2 Layers: Implications for NO and NO2 Gas Sensors

Abstract

Penta-NiN2 is a two-dimensional layered material with pentagonal atomic arrangement and has recently been manufactured in experiments ( ACS Nano 2021, 15, 8, 13539). We study systematically the adsorption of CO, CO2, NO, NO2, NH3, and CH4 on penta-NiN2 nanosheet and its effects on electronic properties employing the first-principles method combined with the nonequilibrium Green’s function. Excellent sensing performance of penta-NiN2 is predicted for the NOx (x = 1, 2) molecules based on energetic, geometric, and electric analyses. The adsorption of NO and NO2 gas molecules may convert penta-NiN2 from a nonmagnetic semiconductor to magnetic metal. A current enhancement around 800% can be observed in penta-NiN2 connected to a circuit after its adsorption of NO. The unique selectivity and sensitivity to adsorption suggest that penta-NiN2 may become a widely used gas sensor for NO and NO2.