Defect modulation and electric field effects on NO2 and NO adsorption on monolayer PdSe2: a first-principles study

The development of efficient and tunable hazardous gas adsorption materials can effectively mitigate the severe threats posed by toxic gases to human health. Based on density functional theory (DFT) calculations, we systematically investigate the adsorption characteristics of NO₂ and NO molecules on monolayer PdSe₂ and further explore the effects of Se vacancy defects (V_Se) and an externally applied vertical electric field on adsorption behavior. Pristine PdSe₂ exhibits physisorption of NO₂ and NO molecules, characterized by low adsorption energies and limited charge transfer. The introduction of Se vacancies significantly enhances the adsorption capacity of PdSe₂, increasing the adsorption energies of NO₂ and NO to − 1.58 eV and  − 1.76 eV, respectively. The adsorption mechanism transitions from physisorption to chemisorption, with gas molecules forming stable covalent bonds with the PdSe₂ surface, accompanied by a substantial increase in charge transfer. Upon adsorption of NO₂ and NO gases, the magnetic moment of PdSe₂ increases from 0 to approximately 0.70 μB, inducing magnetism in the substrate. An externally applied positive electric field further strengthens the adsorption; in contrast, a negative electric field weakens adsorption performance, indicating that PdSe₂'s adsorption properties can be modulated by an external electric field. Finally, compared with NO₂ and NO adsorbed on intrinsic PdSe₂, the recovery times for NO₂ and NO on defective PdSe₂ (V_Se-PdSe₂) are longer, and the interactions are stronger, indicating that V_Se-PdSe₂ is a promising adsorbent for the removal of NO₂ and NO. In summary, the adsorption of NO₂ and NO can modulate the magnetic properties of PdSe₂, while Se vacancies enhance its adsorption capability toward these gases. This work will provide a theoretical basis as well as preliminary ideas for experimenters.

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