Online Monitoring of Faulty Gases (O3, NO2, CO) in Substation Secondary Equipment Based on Cr-Doped BN Sensor: Insights from Density Functional Theory

The secondary equipment of a substation is pivotal for maintaining the safe and reliable operation of the power grid. However, over time, insulation defects can inevitably arise in this equipment. Gas detection in substation secondary equipment has proven to be an effective method for assessing its insulation status. In this paper, we employed a density functional theory (DFT) approach to simulate the adsorption process of three types of fault gases from substation secondary equipment onto Cr-modified BN nanosheets. From the doped and adsorption models, two stable structures were chosen, and by calculating their band structures, density of states, and differential charge density, we uncovered the relevant adsorption and sensing mechanisms. Our findings reveal that Cr-modified BN nanosheets possess robust gas-sensing capabilities, particularly in capturing O3, which is primarily attributable to the contribution of Cr’s 4d orbital electron layer. Specifically, the adsorption capacity of Cr-modified BN nanosheets for fault gases in substation secondary equipment follows the order: O3 > NO2 > CO. The adsorption of Cr-BN on the three target gases mainly tends to be chemisorption accompanied by chemical bond breaking. Notably, there are significant changes in the electronic properties of the adsorbent substrate before and after the adsorption of the target gas molecules, resulting in alterations in its overall conductivity. This research lays the theoretical groundwork for the experimental development of high-performance gas-sensitive sensors designed to detect fault gases in substation secondary equipment.