Defect-Driven MoS 2 Nanosheets toward Enhanced Sensing Sensitivity.

In this study, S-deficient MoS 2 was prepared using proton irradiation and then applied as sensing materials for the detection of NO 2 gas. First, bulk MoS 2 was treated by ultrasonics to produce 2D nanosheets of MoS 2 , which were subsequently bombarded by a flux of high-energy protons, resulting in the appearance of structural defects throughout MoS 2 . The proton fluxes were adjusted to different densities of 1 × 10 11 , 1 × 10 12 , 1 × 10 13 , and 1 × 10 14 ions/cm 2 . The effects of proton irradiation on the defects, also referred to as atomic vacancies, were systematically investigated using Raman measurements to locate the E 1 2g and A 1g modes and X-ray photoelectron spectroscopy to determine the binding energy of Mo 3d and S 2p orbitals. It was revealed that the density of proton irradiation greatly affects the degree of S atom vacancies in irradiated MoS 2 , while also enhancing the n-type semiconducting behaviors of MoS 2 . The vacancy-rich MoS 2 was then demonstrated to exhibit a higher response to NO 2 gas compared to that of nonirradiated MoS 2 , showing a 4-fold increase in response within a concentration range from 1 to 20 ppm. These results could pave the way for new approaches to fabricating sensing materials.