Tuning NO _x Adsorption‐Desorption on AsP Monolayers via Metal‐ <i>d</i> ‐Orbital Occupancy: A Pt/Au Comparative Study

ABSTRACT Using first‑principles DFT, we show that the d ‑electron configuration of a single metal adatom determines the NO x capture mode on N‑doped AsP monolayers. Pt (5 d 9 ) forms bidentate bonds with NO 2 , resulting in near‑irreversible adsorption ( τ ≈ 149 years at 300 K). Yet it can be regenerated at 450 K. Au (5 d 10 ) adopts monodentate coordination, enabling rapid room‑temperature recovery ( τ ≈ 4.7 min). Pt‐N‑AsP is thermodynamically more stable (−2.36 eV) than Au–N‑AsP (−1.85 eV), because P forms stronger orbital hybridization with the substrate. N doping further enhances charge transfer and multi‑site interaction. Both systems are highly selective against O 2 , CO 2 , SO 2 , and NH 3 . This work establishes d ‑orbital occupancy as a design rule to switch 2D materials between reversible sensing and irreversible scavenging.