A CuO/MoO3-based SO2 gas sensor with moisture resistance and ultra-fast response at 90°C

Sulfur dioxide (SO 2 ) is a toxic and harmful decomposition product generated during arc discharge or partial discharge in sulfur hexafluoride (SF 6 ) electrical equipment, which can corrode internal pipelines. Detecting SO 2 is crucial for assessing the insulation condition of equipment and preventing faults. To overcome the challenges faced by traditional SO 2 gas sensors, including high operating temperatures, slow response times, and poor moisture resistance, this paper proposes a novel SO 2 gas sensor based on CuO/MoO 3 . The morphology, composition, and chemical states of the materials were analyzed using different characterization techniques. At 90°C, the S2 sensor (CuO: MoO 3 =1: 1) exhibited a fast response time (10 s) to 10 ppm SO 2 and demonstrated good moisture resistance (a 1 % change in relative humidity (RH) has the same effect on the sensor as 25.9 ppb SO 2 ). The response of the S2 sensor to 100 ppm SO 2 was 26.5. Additionally, the voltage sensitivity of the S2 sensor at low (1–10 ppm) and high (10–100 ppm) concentrations are 658.74 mV/ppm and 33.43 mV/ppm, respectively. Therefore, the S2 sensor is more suitable for low concentration conditions. These good sensing characteristics of the S2 sensor are owing to the high content of oxygen vacancies (39.2 %) and the heterojunction effect in the composite material. Additionally, this sensor exhibits excellent anti-interference capabilities, including moisture resistance and high selectivity. Therefore, the CuO/MoO 3 -based SO 2 gas sensor can be effectively applied to detect the decomposition of SF 6 .