Enhanced NH 3 Sensing Performance of Mo Cluster-MoS 2 Nanocomposite Thin Films via the Sulfurization of Mo 6 Cluster Iodides Precursor.

The high-performance defect-rich MoS 2 dominated by sulfur vacancies as well as Mo-rich environments have been extensively studied in many fields, such as nitrogen reduction reactions, hydrogen evolution reactions, as well as sensing devices for NH 3 , which are attributed to the under-coordinated Mo atoms playing a significant role as catalytic sites in the defect area. In this study, the Mo cluster-MoS 2 composite was creatively synthesized through a one-step sulfurization process via H 2 /H 2 S gas flow. The Mo 6 cluster iodides (MIs) coated on the fluorine-doped tin oxide (FTO) glass substrate via the electrophoretic deposition method (i.e., MI@FTO) were used as a precursor to form a thin-film nanocomposite. Investigations into the structure, reaction mechanism, and NH 3 gas sensing performance were carried out in detail. The results indicated that during the gas flowing, the decomposed Mo 6 cluster iodides played the role of template and precursor, forming complicated Mo cluster compounds and eventually producing MoS 2 . These Mo cluster-MoS 2 thin-film nanocomposites were fabricated and applied as gas sensors for the first time. It turns out that after the sulfurization process, the response of MI@FTO for NH 3 gas increased three times while showing conversion from p-type to n-type semiconductor, which enhances their possibilities for future device applications.