First-Principles Calculations of Two-Dimensional Monolayer PdSe₂ for Selective Sensing of Nitrogen-Containing Gases

Monolayer palladium diselenide (PdSe2) has attracted increasing attention due to its outstanding physicochemical properties and puckered pentagonal layered structure. In this study, the adsorption of nitrogen-containing gases on the surface of monolayer PdSe2 has been investigated by first-principles calculations to fully explore its gas-sensing capability. It is found that NH3 and N2O show physisorption, while NO2 and NO prefer chemisorption, indicating excellent selectivity of monolayer PdSe2. Furthermore, the NH3 and N2O (NO2 and NO) adsorption exhibits a negligible (significant) amount of charge transfer, which in turn leads to a tiny (considerable) change in the electronic structure and magnetic property of the adsorbent surface. In particular, the adsorption of NO2 and NO introduces additional states around the Fermi level, which induces a dramatic decrease of the band gap and appearance of magnetic moments, and further leads to a huge change of the electrical conductivity of monolayer PdSe2. Additionally, the recovery time of the PdSe2 sensor at room temperature is estimated to be considerably short for NO2 and NO. Overall, the present work reveals that two-dimensional monolayer PdSe2 can be used as a promising reusable sensing material featured with high selectivity and excellent sensitivity for environmentally hazardous gas molecules.