Ultrathin WO3 nanosheets modified by g-C3N4 for highly efficient acetone vapor detection

In this work, ultrathin WO 3 nanosheets were prepared by self-assembly approach and their phase and morphology were regulated by changing the heat treatment temperature. Then, g-C 3 N 4 modified WO 3 nanosheets sensitive material was fabricated via a facile liquid ultrasonic mixing method. The microstructure, morphology, chemical composition, oxidation state and surface area of WO 3 nanosheets and g-C 3 N 4 /WO 3 nanocomposite were comparatively studied by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). Sensing performances of WO 3 nanosheets and g-C 3 N 4 /WO 3 composite with different g-C 3 N 4 loading amount were investigated with acetone as a target gas. Compared to WO 3 nanosheets, the g-C 3 N 4 /WO 3 gas sensor exhibits good response, excellent selectivity, transient response and trace detection ability to acetone vapor. Effects of g-C 3 N 4 content on gas sensitivity were also investigated. The response (R a /R g ) of the gas sensor based on 1 wt% g-C 3 N 4 /WO 3 was 35 toward 100 ppm acetone at 340 °C, which was about 300% higher than the response value of pure WO 3 sensor. The sensor also showed a fast response/recovery speed (9 s/3.8 s) and a wide linear detection range (from 0.5 ppm to 500 ppm). These unique sensing properties were attributed to the synergistic effects including the contribution of WO 3 ultrathin nanosheets, suitable crystal phase and porous surface, and the sensitization of g-C 3 N 4 , which increases the specific surface area and regulates the electrical properties. This work will contribute to the development of new acetone sensors and expand the application of g-C 3 N 4 composite materials.