NO2 Sensor Based on WS2/SnSe2 Heterojunction Microflowers

Fast and efficient detection of harmful gases is especially significant for living environments and public health. The combination of two kinds of two-dimensional materials with different properties and morphologies can improve the carrier transmission rate, and the synergistic effect between them can effectively improve the sensing performances. In this study, flower-like SnSe2 and WS2 nanosheets were prepared, and the sensing performance of WS2/SnSe2 nanostructures for NO2 was investigated. The WS2/SnSe2 (1:1 volume ratio) composite material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), and results are described in detail. The WS2/SnSe2 sensor has a shorter response/recovery time (15/14 s) and high response toward NO2. Besides, the sensor exhibits excellent linearity and great selectivity. In addition, we also carried out density functional theory simulations to theoretically analyze and prove the possible sensitivity mechanism of the sensor. It is revealed that the adsorption capacity of SnSe2 for NO2 is enhanced after WS2 doping. The sensing performance can be attributed to the microflower morphology of WS2/SnSe2 and the p–n heterojunction. The WS2/SnSe2 sensor has huge application prospects for NO2 detection.