Density-Functional Theory Study of Snse/Gese Heterostructure for Gaseous Sulfur Hexafluoride Decomposition Products Sensing

Abstract

Partial discharge and local overheating will lead to the decomposition of superior dielectric gas sulfur hexafluoride (SF6) used in gas insulated substations (GIS). Detecting SF6 decomposition gases by gas sensors to diagnose early latent insulation failures is a potential approach to guarantee safety and reliability of GIS. However, the main difficulties lie in sensitivity, operating temperature and sulfur poisoning of the sensor. Metal oxide semiconductor-based gas sensors suffer from high working temperature and sulfur poisoning. Two-dimensional selenides have shown the potential of room temperature gas sensing. Compared with pristine materials, heterostructures usually have narrower band gaps and higher carrier mobility, which promise sensitivity. In this work, a SnSe/GeSe van der Waals heterostructure model is constructed to investigate the gas sensing properties by density functional theory calculations. The SnSe/GeSe heterostructure exhibits huge adsorption energy and comparatively large charge transfer to the SF6 decomposition gases. The calculation results suggest that the excellent sensing properties are contributed to the synergistic effect between the SnSe and the GeSe layers. Besides, the physical adsorption avoids sulfur poisoning of the material. This study provides theoretical bases for the repeatable detection of SF6 decomposition products by SnSe/GeSe heterostructure and its potential in the design of electronic noses.

Keywords: sulfur hexafluoride, heterostructures, post-transition metal selenides, Gas sensing, Density Functional theory