Room-Temperature Ammonia Sensing via Nb₂CTₓ/SnS₂ Nanocomposite Sensors with Enhanced Selectivity

The detection of ammonia (NH3) is essential for environmental monitoring, industrial safety, and medical diagnosis. However, due to fluctuating environmental conditions and limited stability in conventional sensing materials, it is still very difficult to achieve highly selective, highly sensitive, and reliable NH3 sensing at room temperature. To improve NH3 selectivity, we propose a dual-functionalized Nb₂CTₓ/SnS₂ composite containing both amine and carboxyl groups. By combining the superior NH3 adsorption capability of SnS₂ with the outstanding electrical conductivity and surface reactivity of Nb2CTₓ MXene, this composite synergistically produces a highly sensitive and selective chemiresistive sensor. Experimental results reveal the sensor exhibits a low detection threshold of 10 ppm along with a fast response (32 s) and recovery (78 s) at 100 ppm NH3 under ambient conditions. Moreover, under harsh environmental conditions such as exposure to interfering gases, high humidity, and temperature fluctuations, the incorporation of amine and carboxyl groups greatly enhances the sensor's structural integrity and selectivity. For real world applications, this sensor can exhibit exceptional selectivity for NH3 against common interfering gases like formaldehyde, acetone, ethanol, trimethylamine, and CO₂. conditions. Overall, these results highlight the development of a high-performance NH3 sensor that demonstrates promising sensing characteristics under a range of environmental conditions.