Two-dimensional functionalized Mo₂NT₂ (T=H, O) monolayer as promising candidates for NOₓ gas capture agents and sensors

Abstract

This study employs first-principles calculations to investigate functionalized Mo2NT2 (T=Ø, H, O, F) MXenes as dual-functional materials for toxic gas capture and sensing applications. The surface of the pristine Mo2N surface is unsaturated, possesses dangling bonds, and exhibits a strong capability to capture various environmental gases. Surface functionalization significantly modulates this behavior: Mo2NH2 demonstrates remarkable selectivity toward NOx capture, while Mo2NO2 emerges as a superior NO sensor due to its optimal adsorption strength (−0.342 eV), substantial charge transfer (−0.197 e), and 14%–18% current reduction in nanodevice measurements. Notably, investigations of mixed-terminated Mo2NOx(OH)y systems reveal that hydroxyl concentration dictates NO reaction pathways: low OH triggers proton abstraction, forming O-N-H structures, whereas high OH induces direct O-H cleavage, generating H2N-OH. Although water passivation mitigates these reactions, irreversible chemical transformations persist, underscoring that precise control of surface chemistry, particularly terminal-group engineering, is essential for achieving the selective capture capabilities and reversible sensing performance required for next-generation MXene-based gas management platforms.