2D Heterointerface‐Mediated Chemisorption Pathways Enable Selective Dual‐Gas Detection at Room Temperature

ABSTRACT Heterointerfacial modulation in 2D transition metal dichalcogenides (TMDs) offers a unique route to introduce a portfolio of fascinating properties, allowing layered materials to manifest multi‐dimensional features for advanced device applications. Herein, functionally distinct heterostructures of 2H‐MoS 2 are engineered via controlled Ar and O 2 plasma treatments, resulting in 1T/2H‐MoS 2 and MoO 3 /2H‐MoS interfaces, respectively, which in turn facilitate selective gas chemisorption. The tailored heterointerfaces reshape local electronic and surface energy landscapes of 2H‐MoS 2 , where electron transfer from metallic 1T domains strengthens n‐type conductivity, while hole injection from MoO 3 reinforces p‐type behavior. Experimental measurements, supported by density functional theory, indicate that carrier‐density modulation, together with the formation of favorable adsorption sites, governs the chemisorption behavior of oxidizing NO 2 and reducing NH3 molecules. The 1T/2H‐MoS 2 and MoO 3 /2H‐MoS 2 sensors selectively detect NO 2 and NH 3 with minimum detection limits of 165 and 138 ppb, respectively, at room temperature. The practical applicability of the sensors, demonstrated by fabricating a portable sensor array, showcases effective NO 2 detection in vehicular exhaust and NH 3 sensing in spoiled meat, underscoring their potential for environmental and food‐safety monitoring. By strategically engineering heterointerfaces, this study translates tunable TMD properties into chemisorption‐controlled gas discrimination.