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 H₂ 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. [ABSTRACT FROM AUTHOR]