Adsorption and Gas-Sensing Performance of the Small-Molecule Gas on ZrSe₂ Monolayers: A First-Principles Study

The adsorption of five small gas molecules (CO, CO₂, NO, NO₂, and NH₃) on transition metal (TM)-modified ZrSe₂ monolayers (Au-ZrSe₂ and Pt-ZrSe₂) are studied based on first principles. The adsorption structure, adsorption energy (E_ads), electron transfer (Q_t), and density of states (DOS) with intrinsic ZrSe₂, Au-ZrSe₂, and Pt-ZrSe₂ monolayers are discussed, and their sensing performance is evaluated. The results show that the electrical conductivity of ZrSe₂ is obviously increased after Au and Pt atom modification. The intrinsic ZrSe₂ adsorbs the five kinds of gas molecules weakly, while ZrSe₂ modified by the Au or Pt atom improves the adsorption of the gas molecules in different degrees. Au-ZrSe₂ has the best adsorption effect on NO₂ gas molecules, while Pt-ZrSe₂ shows strong sensitivity to CO gas molecules. Moreover, Au-ZrSe₂ and Pt-ZrSe₂ are of great significance for the adsorption sensing mechanism and also offer prospective materials for the advancement of gas-sensitive sensors.