Enhanced Gas Sensing Performance of Surface‐Activated MoS2 Nanosheets Made by Hydrothermal Method with Excess Sulfur Precursor

Abstract

Defect engineering of two‐dimensional (2D) nanostructures is of significant importance for achieving enhanced surface properties in optoelectronic, sensors, and catalytic applications. In this work, the authors study the gas‐sensing properties of 2D molybdenum sulfide (MoS2) nanosheets fabricated using a hydrothermal synthetic route with various nominal S/Mo precursor ratios, in order to generate nano‐domains on the surface. The effect of the excess S precursor on the morphology and the resulting gas sensing performance are investigated by varying the S/Mo precursor ratio in the range of 2–12. Nano‐domains are generated on the MoS2 basal plane for all samples, and their evolution became significant as the S/Mo precursor ratio increases. The presence of the nano‐domains provides additional active edge sites, enhancing the surface‐to‐mass ratio and the resulting gas‐sensing properties. Resistive type gas sensing tests using such 2D MoS2 show that, when the S/Mo precursor ratio is increased from 2 to 12, the sensitivity to 500 ppm NO2 gas at room temperature increased from 27 to 213%.