Ln-Doped ZnO Monolayers (Ln = La, Ce) under Electric Fields for Efficient NO and CO Capture

Abstract

This study employs density functional theory (DFT) to investigate lanthanide-doped ZnO monolayers (Ln = La, Ce) for enhanced gas sensing of NO and CO. Structural analysis reveals stable planar configurations with bonds and widened bandgaps (pristine ZnO: 1.912 eV; doped systems: 2.11–2.15 eV). While pristine ZnO exhibits weak physisorption ( E ads ≈ − 0.18 eV), doping induces strong chemisorption: Ce-ZnO shows preferential affinity for NO ( E ads = − 2.76 eV), whereas La-ZnO favors CO ( E ads = − 2.10 eV). Charge transfer and density of states analyses confirm the presence of covalent interactions. External electric fields significantly modulate adsorption: a negative field (−1 V/Å) deepens binding (e.g., −5.01 eV for NO on Ce-ZnO), while positive fields weaken interactions. Recovery analysis reveals rapid desorption from pristine ZnO (∼10 ns) versus astronomically prolonged retention on doped systems under negative fields (>10 24 s). These results demonstrate ZnO’s dual functionality: pristine for reusable sensors, and Ln-doped variants as irreversible capture materials for toxic gases.