Room temperature and anti-humidity NH3 detection based on GaN nanorods/Ti3C2Tx MXene composite gas sensor

Ammonia (NH3) detection is very important in daily life and industrial production. In this work, GaN nanorods/Ti3C2Tx MXene (GaN/Ti3C2Tx) composite was synthesized by the hydrothermal method and nitridation process to detect NH3. The morphology and elemental composition features of the composite were analyzed by a series of characterization strategies, manifesting the successful synthesis of the GaN/Ti3C2Tx composite. The gas sensing measurements demonstrate that the gas sensor based on GaN/Ti3C2Tx composite has lower limit of detection (0.5 ppm) for NH3 at room temperature compared with the GaN nanorods (10 ppm). And the response of GaN/Ti3C2Tx sensor to NH3 (50 ppm) is 3.4 times higher than that of the Ti3C2Tx. It is interesting that the GaN/Ti3C2Tx gas sensor has the highest response to NH3 at 10 % relative humidity (RH) and the responses to NH3 almost unchanged at 20–80 % RH, exhibiting its excellent anti-humidity, owing to different gas sensing mechanism. Meanwhile, the responses of the GaN/Ti3C2Tx to 100 ppm of NH3 varied less than 4.8 % within 90 days, demonstrating its good long-term stability. The gas sensing mechanism of GaN/Ti3C2Tx material was discussed in detailed. This work can supply a way for improving the anti-humidity and detection efficiency to NH3 for GaN-based composite sensor.