MoO3/TiO2 Nanoparticle-Based Composites for Hydrogen Sensing at Room Temperature

In this study, a series of mesoporous TiO2 nanotablets implanted with uniformly distributed MoO3 were formed by the heat treatment of a titanium-based metal-organic framework (MIL-125) in the presence of Mo ions, and their hydrogen sensing properties were investigated for the first time. The TiO2 and MoO3/TiO2 composites present a typical tablet-like morphology. Compared with the bare TiO2, the MoO3/TiO2 (Mo6+/Ti4+ = 1:10) composite has a richer porous structure (3 times larger than pure TiO2) which can provide a larger surface area (2.1 times larger than pure TiO2). The sensing performance reveals that the MoO3/TiO2 composite (Mo6+: Ti4+ = 1:10) not only exhibits the highest response of 47.57 (5 times higher than pure TiO2) to 1000 ppm of H-2 at room temperature but also shows good reproducibility, long-term stability, and selectivity, which is mainly due to the richer porous structures, the n-n heterojunction, and the catalytic effect between MoO3 and hydrogen. It is noteworthy that the response of the optimal MoO3/TiO2 composite has shown an exponential increase at higher hydrogen concentrations and reaches 1178 at 4000 ppm of hydrogen.