Linear humidity response of carbon dot-modified molybdenum disulfide

Abstract

Molybdenum disulfide (MoS₂)-based humidity sensors suffer from low sensitivity and long response time. Herein, this problem has been effectively solved by modifying MoS₂ nanosheets using carbon dots (CDs) with abundant functional groups via a convenient and facile hydrothermal method. The mechanism for the enhanced humidity response of CD-modified MoS₂ has been proposed through the characterization of physical and chemical properties of the as-prepared composites. The introduction of CDs is expected to enhance the adsorption of water molecules by increasing the specific surface area and surface active sites of the MoS₂ nanosheets. Moreover, a three-dimensional conductive network is jointly established by the chemisorbed water molecules, CDs, and MoS₂ nanosheets, which ensures continuous transmission of charges in a low humidity environment. As a result, the response performance and the repeatability have been significantly improved in CD–MoS₂-based humidity sensors. The response curve shows an excellent linear property in the range of 15–80% RH. This study demonstrates the potential applications of CD-modified two-dimensional nanomaterials with their improved performance towards humidity sensing.