In Situ Growth of a TiO2 Nanosheet on Amorphous Carbonaceous Layer for Sensing NH3 at Room Temperature

The development and manufacture of room-temperature NH3 respiratory gas sensors are particularly important in the medical field. However, current NH3 sensors either lack sensitivity or have slow response and recovery. Herein, in situ growth of TiO2 nanosheet on the layered amorphous C derived from oxidation of Ti3C2Tx by a hydrothermal method is proposed. The resultant gas sensing performance showed that the TiO2-C-2 (hydrothermal reactor for 12 h) specimen exhibited a high gas response value (10.3) and short response and recovery times (69 and 82 s, respectively) to 100 ppm of NH3 at room temperature. In the UV light environment, gas sensitivity is further improved (from 10.3 to 14.2 for 100 ppm of NH3 response value) and response and recovery times are reduced from 69 and 82 s to 50 and 60 s, respectively. Finally, selective adsorption of NH3 was characterized by density functional theory (DFT). This study confirms that the in situ growth of a TiO2 nanosheet on the layered amorphous C for gas-sensitive detection is expected to be a strategy.