A synergistic combination of 2D MXene and MoO 3 nanoparticles for improved gas sensing at room temperature

MXene Ti 3 C 2 T x (30% HF-etched, named Ti 3 C 2 T x -30) plays a pivotal role in the substantial enhancement of the structural modification of molybdenum trioxide (MoO 3 ). Additionally, as the surface MoO 3 molecules come into contact with reducing gas moieties, they actively participate in gas sensing at room temperature. The percentage of Ti 3 C 2 T x -30 in the MoO 3 matrix was varied at 10%, 20%, and 40%, denoted as MM-10, MM-20, and MM-40, respectively. Structural analysis confirmed the composition of the basic elements and evolution of TiO 2 at a higher percentage of Ti 3 C 2 T x -30. Spectroscopy analysis showed the interactions between Ti 3 C 2 T x -30 and MoO 3 , showcasing work functions of 6.91 eV, 6.75 eV, and 7.21 eV for MM-10, MM-20, and MM-40, respectively, confirming MM-20 to be an optimum composition. When the samples were exposed to ammonia gas, MM-20 showed a high response (93% for 100 ppm) at room temperature, with a response time of ∼10 s. Compared to bare MoO 3 , these samples showed ten-fold improvement. The excess electrons on the surface of Ti 3 C 2 T x -30 facilitate the formation of O 2− species, which also provides stability to the otherwise highly reactive MXene surface. These species actively react with ammonia molecules in the presence of adsorbed MoO 3 , thereby changing the resistance of the system. This can be a significant step towards imparting high gas sensitivity to metal oxides at room temperature via incorporation of an optimum percentage of optimized Ti 3 C 2 T x .