Linear humidity response of carbon dot-modified molybdenum disulfide

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.