Fast response/recovery and sub-ppm ammonia gas sensors based on a novel V2CTx@MoS2 composite

Abstract

Ammonia, a colorless gas with a strong irritating odor, is widely found in natural environments. Continuous exposure to ammonia, even at low concentrations, can cause irritation of the eyes, nose, and throat. In severe cases, it may even lead to respiratory distress, lung damage, and death. Therefore, detecting ammonia in a low concentration range is crucial. This study presents the synthesis and characterization of a novel V₂CT_x@MoS₂ composite, focusing on morphology, components, and structure to confirm the successful integration of both materials. Subsequently, its sensing performance for ammonia gas in a low concentration range (0.2–10 ppm) was tested at room temperature (RT, ∼25 °C). The developed V₂CT_x@MoS₂ composite sensor exhibited nearly 8-fold improved response to ammonia with a shorter recovery time of more than 30 s and a detection limit of 129 ppb compared with pure V₂CT_x. In addition, V₂CT_x@MoS₂ demonstrated satisfactory long-term stability and high selectivity for ammonia detection. These results show that the V₂CT_x@MoS₂-based gas sensor is promising for the rapid and stable detection of trace ammonia at RT, thereby contributing remarkably to environmental monitoring, health protection, and energy management.