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 SnSe 2 and WS 2 nanosheets were prepared, and the sensing performance of WS 2 /SnSe 2 nanostructures for NO 2 was investigated. The WS 2 /SnSe 2 (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 WS 2 /SnSe 2 sensor has a shorter response/recovery time (15/14 s) and high response toward NO 2 . 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 SnSe 2 for NO 2 is enhanced after WS 2 doping. The sensing performance can be attributed to the microflower morphology of WS 2 /SnSe 2 and the p–n heterojunction. The WS 2 /SnSe 2 sensor has huge application prospects for NO 2 detection.