Theoretical Study of the Adsorption and Sensing Properties of Cr-Doped SnP Monolayer for Dissolved Characteristic Gases in Oil.

Dissolved gas analysis (DGA) is a vital method for the online detection of transformer operation state. The adsorption performance of a SnP monolayer modified by transition metal Cr regarding six characteristic gases (CO, CH, CH, CH, H, CH) dissolved in oil was studied. The study reveals the relevant adsorption and gas-sensing response mechanisms through calculations of the adsorption energy, density of states, differential charge density, energy gap, and recovery time. The results display a considerable increase in the adsorption effect of the Cr-SnP monolayer on six gases. The CO, CH, and CH gases lead to chemical adsorption, and the CH, H, and CH gases lead to physical adsorption. Combined with the recovery time, the Cr-SnP monolayer has a strong adsorption effect on CO and CH gases at normal temperatures and even high temperatures, and the adsorption is stable. CH gas can be rapidly desorbed from the Cr-SnP monolayer at 398 K. Therefore, the Cr-SnP monolayer can be expected to serve as a CO and CH gas adsorbent and a resistive gas sensor for CH gas. This research offers a theoretical foundation for the development of the Cr-SnP monolayer in gas-sensitive materials.