Homogeneously niobium-doped MoS₂ for rapid and high-sensitive detection of typical chemical warfare agents

Rapid detection of Chemical Warfare Agents (CWAs) is of great significance in protecting civilians in public places and military personnel on the battlefield. Two-dimensional (2D) molybdenum disulfide (MoS₂) nanosheets (NSs) can be integrated as a gas sensor at room temperature (25°C) due to their large specific surface area and excellent semiconductor properties. However, low sensitivity and long response-recovery time hinder the pure MoS₂ application in CWAs gas sensors. In this work, we developed a CWAs sensor based on in-situ niobium-doped MoS₂ NSs (Nb-MoS₂ NSs) via direct chemical-vapor-deposition (CVD) growth. Characterization results show that the high content of Nb elements (7.8 at%) are homogeneously dispersed on the large-area 2D structure of MoS₂. The Nb-MoS₂ NSs-based CWAs sensor exhibits higher sensitivity (-2.09% and -3.95% to 0.05 mg/m³ sarin and sulfur mustard, respectively) and faster response speed (78 s and 30 s to 0.05 mg/m³ sarin and sulfur mustard, respectively) than MoS₂ and other 2D materials at room temperature. And the sensor has certain specificity for sarin and sulfur mustard and is especially sensitive to sulfur mustard. This can be attributed to the improvement of adsorption properties via electronic regulation of Nb doping. This is the first report about CWAs detection based on two-dimensional (2D) transition metal dichalcogenides (TMDs) sensing materials, which demonstrates that the high sensitivity, rapid response, and low limit of detection of 2D TMDs-based CWAs sensor can meet the monitoring needs of many scenarios, thus showing a strong application potential.