Conversion of MoS2 to ternary alloyed MoS2−xSex for resistive NO2 sensors

Abstract

The inert basal planes and strong quantum confinement of 2D materials usually lead to the reduction of carrier transport efficiency and device performance. In this work, a ternary alloyed MoS2-xSex nanocomposites has been prepared by converting few-layered MoS2 nanomaterials through a selenization process to boost the gas sensing performance of gas sensors at room temperature. The selenization process makes the MoS2-xSex nanocomposites generate weak interlayer coupling effect, rich surface defects (states), moderate surface strains, local built-in electric field, and can effectively eliminate oxide impurities in MoS2. Moreover, the band gap of the samples can be tuned from 1.74 eV for MoS2 nanomaterials to 1.49 eV for MoS2−xSex nanocomposites. Owing to the modified surface and electronic structures, the MoS2−xSex nanocomposites exhibit excellent NO2 sensing performance at room temperature in terms of response, repeatability, selectivity, and detection limit. The responses of the best MoS2−xSex nanocomposites are about 2–3 times that of the MoS2 nanomaterials, and its theoretical detection limit reaches 4.0 ppb. This study reveals that ternary alloyed TMDs have better development potential than their binary TMD counterparts in the field of gas sensors.