The gas-sensing mechanism of Nb 2 C monolayer for SF 6 decomposition based on the DFT study

• Published in: Physica scripta Vol. 99; no. 12; p. 125404
• Main Authors: Yang, Dingqian, He, Dandong, Lu, Detao, Yuan, Manman, Zeng, Wen, Zhou, Qu
• Format: Journal Article
• Language: English
• Published: 01.12.2024
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/ad8d48

Abstract During fault analysis of gas-insulated switchgear (GIS), continuous monitoring of the gases produced by the decomposition of SF 6 is critical to the safe operation of the equipment. Although a variety of gas detection technologies are currently available on the market, low-power gas detection devices for SF 6 decomposition products are still in the development stage, and technological advances in this area are of great significance for improving the reliability of GIS systems. Based on the density functional theory (DFT), the Nb 2 C crystal surface structure was established and six adsorption structures of SO 2 , H 2 S, SOF 2 , SO 2 F 2 , HF and CO gas molecules on Nb 2 C crystal surface were constructed by geometrical optimization in this paper. The gas-sensitive properties of each adsorption system were explored in terms of adsorption energy, charge transfer, electron density, density of states and recovery time. The results showed that the Nb 2 C crystal surface was unfit HF and CO gases detection, both of which showed weak physical adsorption; the adsorption energies of SO 2 , H 2 S, SOF 2 , and SO 2 F 2 on the Nb 2 C crystal surface were −1.846 eV, −1.081 eV, −5.270 eV, and −10.582 eV, respectively, and all of them were strong chemical adsorption. It was further shown by theoretical recovery time calculations that the Nb 2 C crystal surface can act as SOF 2 and SO 2 F 2 gas scavengers, and are able to desorb H 2 S (4.69 s) and SO 2 (2.26 s) gases by appropriately increasing the temperature, but the Nb 2 C crystal surface is more suitable for use as a low-power gas-sensitive material for H 2 S gas detection. Therefore, Nb 2 C is anticipated to be a promising material for high response, low-power consumption and fast recovery for H 2 S gas detection in SF 6 decomposition gas.