Enhanced Ammonia Sensing Response Based on Pt-decorated Ti3C2Tx/TiO2composite at Room Temperature.

Herein, we report a Pt-decorated Ti3C2Tx/TiO2gas sensor for the enhanced NH3sensing response at room temperature. Firstly, the TiO2nanosheets (NSs) arein situgrown onto the two-dimensional (2D) Ti3C2Txby hydrothermal treatment. Similar to Ti3C2Txsensor, the Ti3C2Tx/TiO2sensor has a positive resistance variation upon exposure to NH3, but with slight enhancement in response. However, after the loading of Pt nanoparticles (NPs), the Pt-Ti3C2Tx/TiO2sensor shows a negative response with significantly improved NH3sensing performance. The shift in response direction indicates that the dominant sensing mechanism has changed under the sensitization effect of Pt NPs. At room temperature, the response of Pt-Ti3C2Tx/TiO2gas sensor to 100 ppm NH3is about 45.5%, which is 13.8- and 10.8- times higher than those of Ti3C2Txand Ti3C2Tx/TiO2gas sensors, respectively. The experimental detection limit of the Pt-Ti3C2Tx/TiO2gas sensor to detect NH3is 10 ppm, and the corresponding response is 10.0%. In addition, the Pt-Ti3C2Tx/TiO2gas sensor shows the fast response/recovery speed (23/34 s to 100 ppm NH3), high selectivity and good stability. Considering both the response value and the response direction, the corresponding gas-sensing mechanism is also deeply discussed. This work is expected to shed a new light on the development of noble metals decorated MXene-metal oxide gas sensors.