WO3/WS2 Nanoflowers Fabricated by Low-Temperature In-Situ Oxidation for Rapid Detection of Nitrogen Dioxide

Long response time and serious baseline drift have always hampered the practical applications of two-dimensional transition metal sulfides (TMD) in the field of gas sensors. Here, we constructed flower-like WO3/WS2 heterojunction materials via a low-temperature in-situ oxidation method to detect NO2 gas. The WO3/WS2 sensors exhibit satisfactory improvements in the response speed, sensitivity, selectivity, and baseline drift in comparison with the original WS2 sensor. The WO3/WS2 materials with different WO3 ratios were ob-tained by in-situ oxidizing WS2 under different calcination temperatures. The gas-sensing results show that the W-200 sensor has a gas response of Ra/Rg = 2.3-32 ppm NO2, a rapid response time of 27 s, and a low detection limit of 100 ppb, accompanied by good selectivity and reproducibility to NO2 at the optimal working temper-ature of 79 degrees C, making it a promising candidate for the optimization of WS2-based gas sensors in practical use.