Chemiresistive NO₂ gas sensor based on RuO₂/MoS₂ composite

Nitrogen dioxide (NO₂) is a hazardous air pollutant primarily emitted from vehicular exhaust and industrial processes, posing significant risks to both human health and the environment. Despite its importance, conventional NO₂ sensors face several challenges such as low selectivity, high operating temperatures, slow response/recovery times, and material agglomeration during synthesis, limiting their practical application. In this work, a highly sensitive chemiresistive NO₂ gas sensor was developed using a RuO₂/MoS₂ crystalline composite synthesized at relatively low temperature of 200°C. The integration of 2D material such as MoS₂ with its large surface area and RuO₂, which is metallic and highly conductive, enhances charge transport, gas adsorption, and overall sensing performance. Temperature-dependent transport measurements was used to determine the Schottky Barrier Height (SBH) and charge transport mechanisms. The sensor exhibited normalized response across 13–500 ppm NO₂, achieving a 19.35 % response at 13 ppm. It also demonstrated fast response (87 s) and recovery (22 s) times, highlighting its enhanced sensing performance. The rapid response dynamics along with high sensitivity indicates that the composite material has potential for practical use that demands accurate measurement of NO₂ gas for environmental monitoring and safety management.