Adsorption of dissolved gas molecules in the transformer oil on silver-modified (002) planes of molybdenum diselenide monolayer: a DFT study

Abstract

High-sensitivity gas sensor is a crucial online monitoring device to ensure the safe operation of the transformer. In this paper, based on density functional theory, an Ag–MoSe2 monolayer system was established by investigating four different positions of Ag doping to adsorb the dissolved gas (H2, C2H2, CH4, CO and CO2) in transformer oil. The sensing properties of adsorption system for different dissolved gas were studied via the analysis of adsorption energy (E ad), charge transfer, density of state, energy band, lowest unoccupied molecular orbit, highest occupied molecular orbit, and desorption time. Finally, Ag–MoSe2 had good adsorption and desorption properties for CO and CH4 at room temperature, and could be used as a sensor material for the two gases detection. It had strong adsorption and poor desorption performances for C2H2 at room temperature, which could serve as C2H2 scavenger, and simultaneously had good adsorption and desorption performance at a temperature of 358 K, therefore it could be used as a candidate material to detect C2H2 at high temperatures. Ag–MoSe2 had a weak interaction with H2 and CO2, thus was not suitable for detecting the two gases. The results indicated that Ag–MoSe2 had excellent potential in detecting dissolved gases in transformer oil.