N-Doped Ti3c2tx Mxene for Selective and Recoverable Detection of Ammonia at Room Temperature

Herein, a high-performance, room temperature N-doped Ti3C2Tx gas sensor was developed for Ammonia detection with high recovery and resistance stability. Ti3C2Tx nano-layers are derived from the pre-synthesized Ti3AlC2 by selective etching of Al using HF acid. The MXene layers were ultrasonicated, modified, and doped with Nitrogen using NH3 gas at 500˚C. The gas sensing properties of both pristine and N-doped Ti3C2Tx were investigated at room temperature. The pristine MXene had a high sensitivity toward polar gases, especially Ammonia (10% toward 100 ppm Ammonia). However, it had the general drawbacks of Ti3C2Tx as a room temperature gas sensor: weak recovery and resistance drift. We solved the recovery problem of pristine MXene by increasing the temperature of the sensor up to 40˚C during the recovery time, but the resistance drift still remained. In comparison, in N-doped Ti3C2Tx, both the recovery and drift problems disappeared without temperature increment during the recovery time. The sensitivity of the N-doped Ti3C2Tx was 3.69% toward 100 ppm Ammonia which is a notable response for a stable, recoverable, room-temperature gas sensor. To examine and compare the fabricated structures, SEM, TEM, XRD, EDS and FTIR analysis are used.