First-principles study on transition metal (Ni, Cu, Pd, Ag)-doped NbSe 2 for adsorption and sensing of hazardous gases

The accurate detection of hazardous gases such as methane (CH[Formula: see text], carbon monoxide (CO) and ammonia (NH[Formula: see text] is critical for ensuring miner safety in coal mines. Conventional gas sensors suffer from significantly reduced performance in harsh mining environments characterized by high humidity and dust levels. Two-dimensional transition metal dichalcogenides (TMDs) have emerged as promising materials for next-generation gas sensors due to their unique electronic structures and tunable surface reactivity. Using first-principles calculations, this study systematically investigates how transition metal (TM) doping (Ni, Cu, Pd, Ag) modulates the gas-sensing properties of NbSe 2 . The results demonstrate that metal doping substantially improves NbSe 2 ’s gas adsorption capacity. Ni-doped NbSe 2 shows optimal performance for CH 4 ([Formula: see text]0.367[Formula: see text]eV) and NH 3 ([Formula: see text]1.845[Formula: see text]eV), while Pd-doped NbSe 2 exhibits the strongest CO adsorption ([Formula: see text]1.525[Formula: see text]eV). Electronic structure analysis, charge transfer calculations and work function studies reveal the structure-activity relationship between surface electron emission and gas adsorption. Notably, recovery time calculations suggest Ni–NbSe 2 maintains excellent adsorption–desorption equilibrium for CH 4 at room temperature, indicating strong practical applicability. This work elucidates the atomic-scale gas adsorption mechanisms in doped NbSe 2 , providing crucial theoretical guidance for designing advanced gas sensors for mine safety monitoring.