Structural and Electronic Engineering of WSe₂ for High-Performance Gas Sensing

Vertically aligned tungsten diselenide (WSe₂) nanosheets were synthesized via chemical vapor deposition and subsequently modified through nitrogen plasma treatment to obtain nitrogen-doped WSe₂ (N-WSe₂) with enhanced gas-sensing capabilities. The introduction of nitrogen dopants not only preserves the crystalline integrity of the WSe₂ nanosheets but also significantly improves their electrical conductivity and surface reactivity. Chemiresistive gas sensors based on N-WSe₂ demonstrate markedly enhanced sensitivity and lower detection limits toward both nitrogen dioxide (NO₂) and ammonia (NH₃) compared to their pristine counterparts. First-principles density functional theory calculations reveal that nitrogen doping introduces localized defect states that modulate charge transfer and spin polarization upon gas adsorption, thereby facilitating more efficient carrier modulation. This synergistic combination of structural alignment and electronic tuning offers a versatile strategy for engineering high-performance 2D TMD-based gas sensors for environmental and industrial monitoring applications.