Phase-dependent gas sensitivity of MoS₂ chemical sensors investigated with phase-locked MoS₂

In the present study, phase-dependent gas sensitivities of MoS₂ chemical sensors were examined. While 1T-phase MoS₂ (1T-MoS₂) has shown better chemical sensitivity than has 2H-phase MoS₂ (2H-MoS₂), the instability of the 1T phase has been hindering applications of 1T-MoS₂ as chemical sensors. Here, the chemical sensitivity of MoS₂ locked in its 1T phase by using a ZnO phase lock was investigated. To develop MoS₂ chemical sensors locked in the 1T phase, we synthesized a multi-dimensional nanomaterial by growing ZnO nanorods onto MoS₂ nanosheets (ZnO@1T-MoS₂). Raman spectroscopy and x-ray photoelectron spectroscopy analyses of such phase-locked 1T-MoS₂ subjected to flash light irradiation 100 times confirmed its robustness. ZnO nanomaterials hybridized on MoS₂ nanosheets not only froze the MoS₂ at its 1T phase, but also increased the active surface area for chemical sensing. The resulting hybridized material showed better response, namely better sensitivity, to NO₂ gas exposure at room temperature than did 1T-MoS₂ and 2H-MoS₂. This result indicated that increased surface area and heterojunction formation between MoS₂ and ZnO constitute a more promising route for improving sensitivity than using the 1T phase itself. (paper)