In2O3 and Au Nanoparticles Co-Modified WS2 Microsheets for Enhanced NO2 Gas Sensing at Room Temperature

Tungsten disulfide (WS2) is emerging with dazzling visibility as a "layered material beyond graphene and molybdenum disulfide" due to its exquisite tunable electronic, surface structure, high carrier mobility, and physicochemical stability. In this article, In2O3 and Au nanoparticles (NPs) co-modified WS2 microsheets were prepared for detecting NO2 at room temperature (RT). The In2O3 and Au NPs were anchored on the surface of WS2 microsheets, which could be observed by the characterization. The NO2 sensing performance at RT was optimized by adjusting the contents of In2O3 and Au NPs. The proposed gas sensor based on Au1WIn6 (WS2 microsheets co-modified with 6 wt% In2O3 and 1 wt% Au NPs) showed the highest response (46.91 to 50 ppm NO2), limit of detection (LOD; 18.9 ppb), excellent linearity within the test range, and good stability under various relative humidity (RH), bending degrees, and bending times. The excellent result is attributed to the formation of a heterojunction, which increases the number of ionized oxygen adsorption sites and facilitates the reaction between NO2 gas and Au1WIn6. Therefore, it is believed that decorating WS2 microsheets with metal oxide and noble metal NPs is a promising strategy to improve the NO2 sensing property at RT.