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

Abstract

SF 6 -insulated electrical equipment will produce CO gas when it fails. Therefore, effective detection of CO gas can determine whether SF 6 -insulated electrical equipment is operating normally. In this paper, the p-Co 3 O 4 /n-Co 3 S 4 heterojunction was fabricated by two-phase hydrothermal and chemical vapour deposition (CVD) methods for CO detection. The gas sensitivity of the p-Co 3 O 4 /n-Co 3 S 4 heterojunction to CO in both the air and SF 6 background was studied for the first time. The results show that the best operating temperature of the sensor is 200 °C in both air and SF 6 environment. The sensor showed a better response in the SF 6 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-Co 3 O 4 /n-Co 3 S 4 heterojunction on CO is better than that of the p-Co 3 O 4 and n-Co 3 S 4 , and the interaction between p-Co 3 O 4 /n-Co 3 S 4 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. • The Co 3 O 4 -Co 3 S 4 heterojunction was prepared by CVD method for the first time. • The ultra-sensitive detection of ppb-level CO is realized in SF 6 base gas. • A molecular competitive adsorption response mechanism in SF 6 base gas was proposed. • The property of p-Co 3 O 4 /n-Co 3 S 4 to CO was proved by experiment and DFT simulation.