NbCT/MoSe composites for a highly sensitive NH gas sensor at room temperature.

The detection of ammonia (NH)gas holds significant importance in both daily life and industrial production. In this study, the NbCT/MoSe sensor was synthesized using a one-step hydrothermal method and applied for NH detection. The morphology and elemental composition of the composites were analyzed through a series of characterization techniques including XRD, TEM, SEM, and XPS, confirming the successful synthesis of NbCT/MoSe composite with the optimal mass ratio. The sensing performance of the sensor for NH (0.1-100 ppm) was tested at room temperature (∼25 °C). The results showed that, compared to pure NbCT, the sensor based on NbCT/MoSe composite exhibited more stable baseline resistance, a 3.5-fold increase in response to 50 ppm NH, and a reduction in response/recovery time by 56.4 s/32.1 s. Additionally, the sensor's response to NH (1 ppm, 50 ppm, 100 ppm) varied by less than 10 % over 90 days, demonstrating excellent stability. The sensing mechanism of NH by NbCT/MoSe composite is attributed to the formation of a p-n heterojunction and surface charge transfer at the interface between p-type NbCT and n-type MoSe. Finally, the superior selectivity mechanism of the composite for NH was investigated using first-principles calculations. This work opens a new avenue for exploring the application potential of NbCT MXene-based nanocomposites in NH detection.