Ultrasensitive ammonia gas sensor based on Ti3C2Tx/Ti3AlC2 planar composite at room temperature

Two-dimensional (2D) transition metal carbides (MXene) have attracted great attention for device applications due to their unique structures and excellent properties, such as high electrical conductivity and abundant functional groups on the surface. However, gas sensors based on Ti 3 C 2 T x MXene have the problems of high detection limit and poor long-term stability. Herein, we report a simple method to prepare Ti 3 C 2 T x /Ti 3 AlC 2 planar composite gas sensing materials using high molar ratio of HCl and LiF with Ti 3 AlC 2 as a framework. The Ti 3 C 2 T x /Ti 3 AlC 2 planar composite gas sensor has a high sensitivity, good selectivity and low detection limit for NH 3 , which can detect 50 ppb (1.2%) at room temperature ((25 ± 2) ℃). Furthermore, the gas sensor has good repeatability and long-term stability. After 120 days, the response of the gas sensor to 500 ppb of NH 3 fluctuated little due to the Ti 3 AlC 2 as a framework. The superior performances can be attributed to the special heterojunction between Ti 3 C 2 T x and Ti 3 AlC 2 and the high proportion of -O and -OH functional groups on the surface of Ti 3 C 2 T x /Ti 3 AlC 2 composite. This study provides an important reference for the realization of high performance NH 3 sensing by Ti 3 C 2 T x .