Enhanced ammonia sensing response based on Pt-decorated TiCT/TiOcomposite at room temperature.

Herein, we report a Pt-decorated TiCT/TiOgas sensor for the enhanced NHsensing response at room temperature. Firstly, the TiOnanosheets (NSs) aregrown onto the two-dimensional (2D) TiCTby hydrothermal treatment. Similar to TiCTsensor, the TiCT/TiOsensor has a positive resistance variation upon exposure to NH, but with slight enhancement in response. However, after the loading of Pt nanoparticles (NPs), the Pt-TiCT/TiOsensor shows a negative response with significantly improved NHsensing 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-TiCT/TiOgas sensor to 100 ppm NHis about 45.5%, which is 13.8- and 10.8- times higher than those of TiCTand TiCT/TiOgas sensors, respectively. The experimental detection limit of the Pt-TiCT/TiOgas sensor to detect NHis 10 ppm, and the corresponding response is 10.0%. In addition, the Pt-TiCT/TiOgas sensor shows the fast response/recovery speed (23/34 s to 100 ppm NH), 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.