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

In this study, a series of mesoporous TiO 2 nanotablets implanted with uniformly distributed MoO 3 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 TiO 2 and MoO 3 /TiO 2 composites present a typical tablet-like morphology. Compared with the bare TiO 2, the MoO 3 /TiO 2 (Mo 6+ /Ti 4+ = 1:10) composite has a richer porous structure (3 times larger than pure TiO 2 ) which can provide a larger surface area (2.1 times larger than pure TiO 2 ). The sensing performance reveals that the MoO 3 /TiO 2 composite (Mo 6+: Ti 4+ = 1:10) not only exhibits the highest response of 47.57 (5 times higher than pure TiO 2 ) 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 MoO 3 and hydrogen. It is noteworthy that the response of the optimal MoO 3 /TiO 2 composite has shown an exponential increase at higher hydrogen concentrations and reaches 1178 at 4000 ppm of hydrogen.