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

The development and manufacture of room-temperature NH 3 respiratory gas sensors are particularly important in the medical field. However, current NH 3 sensors either lack sensitivity or have slow response and recovery. Herein, in situ growth of TiO 2 nanosheet on the layered amorphous C derived from oxidation of Ti 3 C 2 T x by a hydrothermal method is proposed. The resultant gas sensing performance showed that the TiO 2 -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 NH 3 at room temperature. In the UV light environment, gas sensitivity is further improved (from 10.3 to 14.2 for 100 ppm of NH 3 response value) and response and recovery times are reduced from 69 and 82 s to 50 and 60 s, respectively. Finally, selective adsorption of NH 3 was characterized by density functional theory (DFT). This study confirms that the in situ growth of a TiO 2 nanosheet on the layered amorphous C for gas-sensitive detection is expected to be a strategy.