A synergistic combination of 2D MXene and MoO3 nanoparticles for improved gas sensing at room temperature

Abstract

MXene Ti3C2T x (30% HF-etched, named Ti3C2T x -30) plays a pivotal role in the substantial enhancement of the structural modification of molybdenum trioxide (MoO3). Additionally, as the surface MoO3 molecules come into contact with reducing gas moieties, they actively participate in gas sensing at room temperature. The percentage of Ti3C2T x -30 in the MoO3 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 TiO2 at a higher percentage of Ti3C2T x -30. Spectroscopy analysis showed the interactions between Ti3C2T x -30 and MoO3, 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 MoO3, these samples showed ten-fold improvement. The excess electrons on the surface of Ti3C2T x -30 facilitate the formation of O2− species, which also provides stability to the otherwise highly reactive MXene surface. These species actively react with ammonia molecules in the presence of adsorbed MoO3, 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 Ti3C2T x .