CVD-fabricated Co3O4-Co3S4 heterojunction for ultra-sensitive detection of CO in SF6 discharge decomposition products

SF6-insulated electrical equipment will produce CO gas when it fails. Therefore, effective detection of CO gas can determine whether SF6-insulated electrical equipment is operating normally. In this paper, the p-Co3O4/n-Co3S4 heterojunction was fabricated by two-phase hydrothermal and chemical vapour deposition (CVD) methods for CO detection. The gas sensitivity of the p-Co3O4/n-Co3S4 heterojunction to CO in both the air and SF6 background was studied for the first time. The results show that the best operating temperature of the sensor is 200 degrees C in both air and SF6 environment. The sensor showed a better response in the SF6 background than in the air background, but the recovery time was longer in the air background. At the same time, the sensor has good selectivity for CO in both environments, resistance to moisture, and long-term stability. In addition, it is proven by first principles that the adsorption performance of the p-Co3O4/n-Co3S4 heterojunction on CO is better than that of the p-Co3O4 and n-Co3S4, and the interaction between p-Co3O4/n-Co3S4 heterojunction and CO is further described by differential charge density and state density curves. The designed and constructed carbon monoxide detection system can realise the effective detection and alarm of carbon monoxide gas concentration.