Chemiresistive detection of SO2 in SF6 decomposition products based on ZnO nanorod/MoS2 nanoflower heterojunctions: Experimental and first-principles investigations

Abstract

Sulfur dioxide (SO2) is a typical gas in SF6 discharge decomposition components. The detection of SO2 can reflect the safe operation of SF6 gas insulation equipment. In this paper, the ZnO nanorod/MoS2 nanoflower (ZnO NR/MoS2 NF) heterojunction was prepared by hydrothermal and physical mixing methods for the ultra-sensitive detection of SO2. In the two test environments of the air and SF6, the response and recovery time of the ZnO NR/MoS2 NF heterojunction sensor to 30 ppm SO2 are 52 s/5 s (11 s/7 s), respectively, and the response value of the sensor are 46.12% (47.33%) at 250 °C. The sensor shows excellent selectivity, moisture resistance, and long-term stability. Furthermore, it has been demonstrated through first principles calculations that the ZnO/MoS2 heterogeneous composite exhibits superior adsorption performance for SO2 compared to ZnO and MoS2 alone. The sensor mechanism in the air is mainly described as the interaction between SO2 and oxygen adsorbed on the surface of the sensitive material. The sensing mechanism under SF6 background gas can be described as the competitive adsorption of SO2 molecules with lattice oxygen molecules on the surface of ZnO NR/MoS2 NF heterojunction, and the reaction of F2− adsorbed on the surface of ZnO/MoS2 heterojunction with SO2 molecules.